Advances in Carbohydrate Chemistry and Biochemistry Volume 52
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Advances in Carbohydrate Chemistry and Biochemistry Volume 52
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Advances in Carbohydrate Chemistry and Biochemistry Editor DEREK HORTON The American Universiry Washington,DC
Board of Advisors GUYG. S. DWITON LAURENS ANDERSON fhl%”llP J. ANGYAL STEPHEN HANESSIAN HANSH. BAER BENGTLINDBERG CLINTON E. BALLOU HANSPAULSEN NATHANSHARON JOHNS. BRIMACOMBE J. F. G. VLIEGENTHART J. GRANT BUCHANAN ROY L. WHISTLER
Volume 52
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CONTENTS PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ix
Maurice Stacey 1907- 1994 PAUL F~NCH AND w. GEORGE OVEREND Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. ..
... 1 . . . 20
Nomenclature of Carbohydrates Preamble 2.Cab.0 . 2-Cab- 1. 2.Cab.2 . 2.Cab.3 . 2.Carb.4 . 2.Cab.5 . 2.Carb.6 . 2.C~b.7 . 2.Cab.8 . 2.Cab.9 . 2.Cab.10 . 2-Carb- 1 1. 2-Cab- 12. 2.Carb.13 . 2-Carb- 14. 2.C~b.15 . 2-Cab- 16. 2.Carb.17 . 2-Carb- 18. 2.Carb.19 .
............................................. Historical Development of Carbohydrate Nomenclature . . . . . . . . . . . . . . Definitions and Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . Parent Monosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Fischer Projection of the Acyclic Form . . . . . . . . . . . . . . . . . . . . Configurational Symbols and Prefixes . . . . . . . . . . . . . . . . . . . . . . . Cyclic Forms and Their Representation . . . . . . . . . . . . . . . . . . . . . . Anomeric Forms: Use of LY and j3 . . . . . . . . . . . . . . . . . . . . . . . . . . Conformation of Cyclic Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . Aldoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dialdoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ketoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Diketoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ketoaldoses (Aldoketoses. Aldosuloses) . . . . . . . . . . . . . . . . . . . . . . Deoxy Sugars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amino Sugars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thio Sugars and Other Chalcogen Analogues . . . . . . . . . . . . . . . . . . . Other Substituted Monosaccharides . . . . . . . . . . . . . . . . . . . . . . . . Unsaturated Monosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . Branched-Chain Sugars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Alditols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
V
47 48 49 53 56 57 59 65 68 72 74 75 78 79 80 84 86 87 91 97 102
vi
CONTENTS
2.Carb.20 . 2-Cab-2 I . 2.Carb.22 . 2.Cab.23 . 2.Cab.24 . 2.C~b.25 . 2.Ci~b.26. 2.Cab.27 . 2.Cab.28 . 2.Carb.29 . 2.Cab.30 . 2-Cab-3 1 . 2.Carb.32 . 2.Cmb.33 . 2.Cab.34 . 2.Cab.35 . 2.Carb.36 . 2.Cab.37 . 2.Cab.38 . 2.Cab.39 .
Aldonic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 106 Ketoaldonic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Uronic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 110 Aldaric Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 N-Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 118 Intramolecular Anhydrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Intermolecular Anhydrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Cyclic Acetals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Hemiacetals, Hemiketals. and Their Thio Analogues . . . . . . . . . . . . . . . 122 123 Acetals, Ketals. and Their Thio Analogues . . . . . . . . . . . . . . . . . . . . . Names for Monosaccharide Residues . . . . . . . . . . . . . . . . . . . . . . . 12.5 129 Radicals. Cations. and Anions . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Glycosides and Glycosyl Compounds . . . . . . . . . . . . . . . . . . . . . . . Replacement of Ring Oxygen by Other Elements . . . . . . . . . . . . . . . . . 140 143 Carbohydrates Containing Additional Rings . . . . . . . . . . . . . . . . . . . . 148 Disaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Higher Oligosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Use of Symbols for Defining Oligosacchaide Structures . . . . . . . . . . . . . 1.59 163 Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Thioglycosidesas Glycosyl Donors in OligosaccharideSynthesis PERI. GAREGG I. I1. 111. Iv. V. VI . VII . VIII. IX .
General Introduction: Glycosidation Methods for Oligosaccharide Syntheses . . . . . . 179 181 Preparation of Thioglycosides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conversion of Thioglycosides into Other Glycosyl Donors . . . . . . . . . . . . . . . 183 In Situ Generation of Glycosyl Halides from Thioglycosides . . . . . . . . . . . . . . 184 Direct Use of Thioglycosides by Means of Thiophilic Activators . . . . . . . . . . . . 18.5 Thioglycosides in Block Synthesis of Oligosaccharides . . . . . . . . . . . . . . . . . 191 ThioglycosidesasGlycosylAcceptorsinOligosaccharideSynthesis . . . . . . . . . . 197 Glycosyl Sulfoxides. Sulfones. and Selenoglycosides as Glycosyl Donors . . . . . . . 198 200 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
Dihexulose Dianhydrides MERILYN MANLEY-HARRIS AND GEOFFREY N . RICHARDS I . Introduction
........................................
207
CONTENTS
vii
I1 . Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
208 210 Di-o-fructose Dianhydrides from Natural Sources . . . . . . . . . . . . . . . . . . . . 213 Dihexulose Dianhydrides by Prontonic and Thermal Activation of Saccharides . . . . . 216 Conformational Energies in Dihexulose Dianhydrides and the Control of Product 224 Distributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Di-o-fructose Dianhydrides and Industry . . . . . . . . . . . . . . . . . . . . . . . . . 232 Uses of Dihexulose Dianhydrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 235 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
111. Historical Overview
IV. V. VI . VII . VIII .
....................................
Sugars and Nucleotides and the Biosynthesis of Thiamine SERGE DAVIDAND BERNARD ESTRAMAREIX 268 I . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1. I-Deoxy-o-fhreo-pentulose as the Precursor of the Five-Carbon Chain of Thiazole in 215 Escherichia coli Cells and Spinach Chloroplasts . . . . . . . . . . . . . . . . . . . . . I11. Chemistry and Biochemistry of 1-Deoxy-o-threo-pentulose . . . . . . . . . . . . . . . 217 IV. A Pentulose or Pentulose Derivative as the Precursor of the Five-carbon Chain of the 288 Thiazole of Thiamine in Yeasts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V. 5-Amino-1-(P-o-nbofuranosyl)imidazole5’.Phosphate. the Precursor of Pyramine 292 in Enterobacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 VI . Pyramine Synthesis in Yeasts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VII . The Distribution of the Four Biosynthetic Routes in Nature . . . . . . . . . . . . . . . 305 306 VIII . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Molecular Architecture of Polysaccharide Helices in Oriented Fibers RENGASWAMI CHANDRASEKARAN
I . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Polysaccharide Fiber Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . X-Ray Diffraction Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (1 + 4)-Linked Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (1 + 3)-Linked Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (1 + 4) ( 1 -+ 3)-Linked Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . The Gellan Family of Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . VIII . More Branched Polysaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1 . 111. IV. V. VI . VII .
.
312 313 314 326 356 364 383 393 401
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Sucrose Decomposition in Aqueous Solution and Losses in Sugar Manufacture and Refining MARGARET A. CLARKE. LESLIE A . EDYE.AND GILLIAN EGGLESTON I . Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441 I1 . Alkaline Degradation of Sucrose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 444 111. Alkaline Degradation of Monosaccharides . . . . . . . . . . . . . . . . . . . . . . . . 449 IV. Acid Hydrolysis of Sucrose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455 V. Acid Degradation of Monosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . 457 V1. Effects of Degradation Reactions on Sucrose Manufacture . . . . . . . . . . . . . . . 458 466 VII . Glossary of Sugar Industry Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
AUTHOR INDEX FOR VOLUME 52 FOR VOLUME 52 SUBJECT INDEX
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471 483
PREFACE In his preface to Volume 8 of Advances, published in 1953, M. L. Wolfrom, the founding editor, noted that “Carbohydrate nomenclature has been an everpresent problem in this series . . .” and drew attention to the agreement between American and British carbohydrate chemists that resulted in the published “British- American Rules of Carbohydrate Nomenclature.” A revision of that document was published in 1962, to be followed seven years later by an internationally proposed set of guidelines for naming carbohydrates and their derivatives. Since the early 1970s a panel convened by the International Union of Pure and Applied Chemistry and the International Union of Biochemistry and Molecular Biology has been working to formulate recommendations for carbohydrate nomenclature that meet developing needs of research and electronic data handling, while retaining links to the established literature base on carbohydrates. The realization of these endeavors is presented here in the final document “Nomenclature of Carbohydrates,” which provides a definitive reference for current researchers, both in the text version and in the version accessible where on the World Wide Web (http://www.chem.qmw.ac.uk/iupac/2carbl), amendments and revisions are maintained. Garegg (Stockholm), in his chapter on thioglycosides as glycosyl donors, presents a wealth of practical detail on a technique of wide utility for constructing complex oligosaccharides. Much of the work is from his own laboratory. His article complements that by Schmidt in Volume 50 on the trichloroacetimidate method of glycoside synthesis. These two articles chronicle important advances that have been made in the chemical construction of larger oligosaccharides. Glycosidic coupling methodology nevertheless still falls far short of synthetic methods now standard for oligopeptides and oligonucleotides, where automated syntheses based on solid-phase procedures are routine. There remains considerable scope for further development. Manley-Harris and Richards (Missoula, Montana) have compiled a comprehensive account of the dianhydrides of D-fructose and related compounds, more than 30 in all. These compounds, several of which are of importance in the sugar industry, have in the past presented significant problems in their chemical characterization. Their chemistry was surveyed as early as 1945 by McDonald in Volume 2 of this series, and discussed again in Volume 22 by Verstraeten. The current article furnishes detailed NMR data for each of the anhydrides, providing definitive reference data for accurate identification and correlation with earlier literature, where erroneous structural attributions are rather frequent. The vitamin thiamine may not at first sight have a close relation to carbohydrates, but David and Estramareix (Paris) trace here a remarkable story in the elucidation of its biosynthesis. Quite different pathways are shown to exist in ix
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PREFACE
prokaryotic and eukaryotic organisms, each involving sugar intermediates, and comparisons offer interesting insight into pathways of biochemical evolution. X-Ray diffraction analysis of oriented polysaccharide fibers has had a long history. Marchessault and Sarko discussed this topic in Volume 22 of Advances, and a series of articles by Sundararajan and Marchessault in Volumes 33, 35, 36, and 40 surveyed ongoing developments. The comprehensive account presented here by Chandrasekaran (West Lafayette, Indiana) deals with some 50 polysaccharides, constituting a wide range of structural types, where accurate data and reliable interpretations are available. The regular helical structures of the polysaccharide chains, and associated cations and ordered water molecules, are presented in each instance as stereo drawings and discussed in relation to observed functional properties of the polymers. The final chapter, by Clarke, Edye, and Eggleston (New Orleans, Louisiana), deals with the centuries-old technological problem of maximizing yield in the extraction of sucrose from cane or beet juice. Somewhat remarkably, important misconceptions about the fundamental aspects of alkaline degradation of sucrose still persist. The authors of this chapter effectively interpret traditional sugar technology, based largely on empirical art,in clear terms of accepted fundamental principles of chemistry. The most influential and accomplished British carbohydrate chemist since Sir Norman Haworth was his protCgC, Maurice Stacey, who in his long career made broad contributions that bridged chemistry and biology long before the interdisciplinary approach came into vogue. The story of Stacey’s life and work, detailed here by Finch and Overend (London), paints a warm picture of a man whose contribution in motivating many young scientists into research careers on carbohydrates was as significant as his own wide-ranging research program. With regret, the passing is noted, on April 16, 1997, of Guy G. S. Dutton, a member of the Board of Advisors of Advances for many years and a staunch supporter of the series. Also deceased in 1997 are two giants of science, Melvin Calvin and Alexander Todd, Nobel laureates, each of whom made seminal contributions in the carbohydrate field. Washington, DC April 1997
DEREKHORTON
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ADVANCES IN CARBOHYDRATE CHEMISTRY AND BIOCHEMISTRY, VOL. 52
MAURICE STACEY
1907- 1994 Maurice Stacey was a remarkable man who had a fulfilling and varied life. His contributions to chemistry were substantial and internationally renowned. Throughout his career, he had an abiding passion to unravel the intricate processes of nature and to strengthen the scientific basis of medicine and agriculture. He successfully bridged organic and biological chemistry at a time when the latter was a relatively young science. But his influence on British science extended well beyond his own research as he participated in the management of science through his service on governmental committees and the Councils of the Scientific Societies. Stacey was not a scientist whose success was achieved by a single-mindedness that excluded all else. He was a polymath and, besides science, was involved in other pursuits, which led to him being well known and respected beyond the fraternity of chemists. He inspired his students, both the high flyers and the less gifted, and imparted his broad understanding of science. The first and lasting impression of Maurice Stacey was of someone who had a warmth of spirit and who caught the imagination. Not surprisingly, Maurice always had the demeanor of a countryman, and he remembered and recalled with affection his early upbringing in a rural part of England. His birthplace was in the hamlet of Bromstead, located in the village of Moreton on the Staffordshire border. It is about 5 miles from Newport, Shropshire. The family owned some land in Shropshire, and Stacey always considered himself to be a Shropshire man. Born April 8, 1907, he was the middle child of John Henry and Ellen (Titley) Stacey, having an elder brother and a younger sister. Both his mother and father had interests in farming. She was a farmer's daughter, trained in dairy work at Radbrook College, near Shrewsbury. After employment in the family business, connected with construction work on farms and selling timber, his father managed a farm during World War I. This necessitated a move, so when Maurice was 7 years old, the family left the smallholding of about 30 acres at Bromstead to reside at Waltonfields Farm. At the end of the war in 1918, the Waltonfields farmer returned, and the Stacey family moved back to their cottage.
0096-5332i97 $25."l
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Copynght 0 1997 by Academic Press. All nghts of reproduction in any form reserved.
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PAUL FINCH AND W. GEORGE OVEREND
At these sites, Maurice passed his childhood, a period he enjoyed very much and where he learned country pursuits and animal husbandry-as he said, “We always had two pigs in the sty, one to sell and one to keep.” Subsequently, after several transitory jobs, his father secured the position of general builder on a local estate. He did not live to see Maurice’s major successes. In his early sixties, he tried to release a cat from a trap and was badly bitten. From this incident, he died from septicemia in 1938. Maurice always spoke with gratitude of the encouragement he received from his parents. The parents were indulgent and his childhood was spent in a very free and easy manner. No doubt it was in these formative years that he acquired the seemingly relaxed attitude of his subsequent life. Other early experiences left a mark. One of his earliest recollections was fracturing his arm at the age of 2, which resulted in his arm being permanently slightly crooked. This prevented him from playing rugby, but it had no other restricting effect, and he became a member of both cricket and soccer teams. At the age of 4-5, he was given a piece of land in the home garden and some small tools. This started his lifelong love of gardening and horticulture. As a youth, he exhibited at local shows and learned the “tricks of the trade,” which he practiced so effectively as an exhibitor in later life. An enormous amount of fruit was grown each year in the many acres of his aunt’s neighboring farm and his family’s smallholding, and he became knowledgeable about fruit of all kinds. These horticultural interests turned professional when he became a member (1960- 1974) of the Governing Body and the Executive Council of the National Vegetable Research Station. He was a member and was later named chairman (1956-1961) of the Research Committee (mainly concerned with cider production) of the Long Ashton Research Station. As a teenager, he augmented his income with prize money from flower shows; these commercial activities continued during the 1939- 1945 war. Market gardens in his area were not then allowed to grow anything except food, and he made money by growing and selling flowers, particularly chrysanthemums. His education commenced at the local Moreton Church of England School (1911-1920), where he found little in common with the other pupils and confessed to being lonely. Life changed when he moved to Adams Grammar School (1920- 1926) in Newport. There, he had an outstanding academic career, being awarded a school bursary and medals, prizes, and colors for football (soccer), cricket, and athletics. He gained first place in the Shropshire County Council examination for Training Colleges. Clearly, his parents, when urging him “to get on,” envisaged a career in teaching, but other things were in store for him. He entered the University of Birmingham in I926 and became a pupil of Professor w. N. Haworth [Adv. Carbohydr. Chem., 6 (1951) 1-91, who (at that time) was head of the department of chemistry. He made steady progress through the university curriculum and graduated in 1929. The Research School was organized on a team basis (Haworth’s so-called syndicates) and he joined
MAURICE STACEY
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one of the teams, supported by a teaching scholarship. In the vitamin C work, he saw the advantages of this organization and, when he became a research director, he adopted a similar approach. He regarded it as part of his job to seek actively, some would say “aggressively,” funds to support his research teams. This started at a time when it was not always considered academically respectable to seek sponsorship for research projects from industrial and government sources. Between academic terms in the period 1929-1933, he traveled regularly to the London School of Hygiene and Tropical Medicine to participate, on a parttime basis, in research at Professor Raistrick’s laboratory on the complex carbohydrates of molds and bacteria. Stacey’s Ph.D. thesis, “Investigation into the Ascent of The Series and High Polymers in the Carbohydrate Group,” based on work camed out in both Birmingham and London, was presented in May 1932. In 1933, he moved full-time to the London School of Hygiene and Tropical Medicine. In 1936, Haworth offered him a lectureship at Birmingham. A reduction in salary was to be compensated by his assignment to a research group. He left London with mixed feelings and without the goodwill of Raistrick. Back in Birmingham, his first task was to create a laboratory for the teaching of microanalysis. After a term, he gained a traveling fellowship, and he and his wife went to Columbia University for a few months. There, he worked in Professor M. Heidelberger’s laboratory and formed a permanent friendship with this immunochemist. Maurice recorded that the experience in New York was quite wonderful and served as a standard for the rest of his life. He returned to his post in Birmingham and remained there for the rest of his career. Stacey scaled the academic ladder rapidly: He was appointed reader in 1944 and gained a personal chair in 1946. When Haworth retired in 1948, he assumed further responsibilities as professor in charge of organic and biological chemistry. From 1956 to his retirement in 1974, he was Mason professor of chemistry and head of department. Thereafter, he continued for some years as honorary senior research fellow in radiation chemistry and maintained his chemical, educational, and family interests. His eldest daughter had settled in the United States, and Maurice combined regular trips to visit her and her family with visits to U. S. carbohydrate chemists and to meetings of the American Chemical Society. Full of years, Maurice died on October 21, 1994, and his death removed from our midst the most senior carbohydrate chemist then in the United Kingdom. As head of department, he was responsible for planning the new, extensive, and well-equipped Haworth Laboratories. Additionally, onerous duties in the university culminated in his election in 1963 as dean of the faculty of science and engineering at a time of great development and change. Service on innumerable university committees was indicative of the value accorded to Stacey ’s advice. Calls to help the wider community were frequent and, always, he seemed able to find time to assist. For 15 years, he was chief scientific advisor for civil defence in the Midland Region of the United Kingdom. As a member of the
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Home Office Science Advisory Council (1967- 1975), he advised the police. Several other departments of state, research councils, and higher-education funding agencies also sought his assistance. He was a very effective promoter of carbohydrate chemistry on the world scene (as well as in Britain), and many Birmingham-trained workers moved to independent careers in North America and other parts of the world. In particular, his long personal friendship with M. L. Wolfrom of the Ohio State University led to a succession of Birmingham graduates who studied in Wolfrom’s laboratory and later led carbohydrate groups: R. Montgomery (Iowa), F. Shafizadeh (Montana), A. B. Foster (Birmingham and London), J. M. Webber (Birmingham), and D. Horton (Ohio State). He always maintained close contacts with industry, and actively promoted collaboration between universities and both industrial companies and government institutions. Consultancies with many companies were undertaken in connection with research grants to his department. These contacts formed an important part of his life, and he claimed they were a great stimulation to him. He was a protagonist of the utilization of carbohydrates as chemical raw materials, although at the time they did not find many industrial outlets because of the development of the petrochemical industry. Now, however, many of his concepts have reemerged under the fashionable umbrella of biotechnology. Besides gardening, for relaxation, he was fond of traveling. He assembled magnificent and valuable collections of drug jars, pictures of alchemists, and old scientific and other books about which he was knowledgeable.* Additionally, his extramural interest in schools gave him much satisfaction, and his talks at area schools were profoundly inspirational to some young people whose career decisions were motivated by his ability to communicate the excitement of new discoveries at the frontiers of biological chemistry. Those who knew the amply-proportioned Maurice of his later years were surprised to be told of his former sporting prowess. He had represented the university in athletics, cricket, and soccer, and after his playing days, he maintained connections with sport. As a senior member of the university, preoccupied with important duties, he continued to give support to student athletics and swimming, and was an honorary life member of the Amateur Athletic Association. Above all, his wife and family were ever at the forefront of his thoughts; for him, it could not have been otherwise. In January 1937, he married a fellow student, Constance Mary Pugh, who provided him with unflagging, but unobtrusive, support. They had two sons and two daughters. Mrs. Stacey died in 1985 and their youngest son died in 1980 at the early age of 29. *When the new Hills extension was opened, a large mural featuring alchemical symbols and motifs radiating from a central sun was commissioned to adorn the foyer. Inspection of the golden orb revealed a beaming face bearing the unmistakable features of the department’s leader.
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Chemists tend to be prolific authors. Some say they have a conceit of authorship, whereas others contend it is pride. Stacey was certainly proud of his many scientific papers (more than 350) and several books. In addition, he was foundereditor of three journals and he was a member of the editoriai boards of several others. He was a supporter of Advances in Carbohydrate Chemistry from its inception. He served on the advisory board for many years, was associate editor, and contributed to early volumes. It is not possible to adequately summarize in this chapter the long life and the diverse contributions of Stacey. The most that can be done is to direct attention to the main achievements and the new directions that resulted from his work. The influences of Raistrick, Heidelberger, and particularly Haworth are obvious. As a man of strong personality, Haworth was not always the easiest of colleagues to work with, but Stacey’s temperament enabled him to sustain a collaboration for a quarter of a century. He treasured the collaboration. Near the end of his career, he wrote of Haworth “I came under the influence of his strong personality and yet was able to work in full harmony with him-his powerful influence is still with me.” In a way, there is a paradox in this influence when one asks the question-“Why did Haworth direct Stacey ’s attention to biological chemistry?” It was often rumored that, like many other leading organic chemists of his day, Haworth was hostile to biochemistry. Some have good reason to believe the rumors, but Stacey maintained they were untrue and that Haworth was always fascinated by biological systems and all matters medical, and passed on those enthusiasms. Stacey started research in an inspiring and stimulating atmosphere that he strove to maintain, add to, and develop when it became his turn to lead the department. His earliest research was with Haworth and his key partner E. L. Hirst [Adv. Carbohydr. Chem. Biochem., 35 (1978) 1-29] on aspects of the chemistry of “glucoheptose.” His first publication with them in 193I was entitled “Walden Inversion in the a-Glucoheptose Series,” followed in the next year by a report on the methylation of monocarboxylic acids derived from aldoses and the structure of “pentamethyl a-gluco-heptonolactone.”He found this to be a difficult project because, initially, he could not crystallize his stock of glucoheptose. Then, as later, he found crystallization to be a challenging problem. In 1932, all the resources of the Birmingham laboratories were utilized by Haworth to tackle the problems of the structure and synthesis of Szent Gyorgi’s “hexuronic acid,” which later became known as vitamin C (“Godnose” to the research group). Haworth assembled a team to undertake an intensive investigation of this substance, which presented many unusual features. Although not a member of the group that studied the structure, Stacey was a leading member of the team that synthesized ascorbic acid, identical in all respects with natural vitamin C . His contribution was awarded the Meldola Medal in 1933. This spectacular synthesis was achieved simultaneously by Swiss chemists and led to the
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present-day industrial-scale synthesis. In 1991, Stacey recalled the thrill of “seeing a silo holding 30 tons of glucose and mountains of 200-pounds bags of beautifully crystalline vitamin C” at the Roche plant at Dalry. After completing the synthesis, workers in many laboratories then commenced a search for physiologically active analogues; several were made in the Birmingham laboratories. A decade later, this topic was still of interest to Stacey, and with Lilian Turton, he reported that “tetra-acetylglucosone” hydrate provided a convenient initial material for the syntheses of analogues of ascorbic acid. The award of a Beit Memorial Fellowship for medical research in 1933 provided him with more financial security and independence. Stacey moved to London and for the next 3 years worked full-time in Raistrick’s laboratory. He was given the task of working on vaccines against typhoid fever. The work was successful eventually and the vaccines were used by the Royal Air Force and also were sent to the Air Force in New Zealand. Also, some advances were made in studies of the carbohydrate components of the vaccines. In addition to this research, he completed, by part-time study, the diploma course in bacteriology. During his career, Stacey’s research encompassed a wide spectrum of chemistry; even within biological chemistry, his interests were broad. There can be no doubt, however, that bacterial polysaccharides and immunochemistry were his favorite topics. By deciding early in his career to unravel the structures of bacterial polysaccharides, he was striking out boldly in a new direction. At the time he started, the problems posed were formidable. Experimental difficulties were immense, and the techniques essential for making progress were only just beginning to be developed. Apart from the extensive studies of polysaccharides of micro-organisms, described next, five papers published in the 1940s on animal glycoproteins pioneered the chemical analyses of these substances. A seminal review by Stacey in 1947 on “Aspects of Immunochemistry,” and a survey a year later on “Chemistry of Immunopolysaccharides,” pointed the way to much of his future research. Taken in toto, his chemical work laid a firm basis for correlating the chemical and serological approaches to structure determinations of antigenic polysaccharides. The following examples illustrate his early work. As substances of importance for an understanding of bacterial and immunological specificity, the structures of the polysaccharides derived from Pneumococcus Types I, 11, 111, V, and XIV were examined in his laboratory. Historically, the polysaccharide from Pneumococcus Type II was of particular interest. As the “soluble specific substance” of Type I1 Pneumococcus, it was the first of the capsular materials to be recognized in 1924 as a polysaccharide. From its specific cross-reaction with Type 111 antiserum, it was concluded that glucose and glucuronic acid units formed a part of its molecular architecture. This was confirmed by Stacey’s chemical work. Beginning in 1955, he and Butler undertook a chemical investigation of the purified
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polysaccharide; from the results, they were able to suggest a possible repeating unit for the Type I1 polysaccharide. In 1967, Heidelberger, Stacey et al. reported the purification, some structural features, and the chemical modification of the capsular polysaccharide from Pneumococcus Q p e I. Difficulties of direct hydrolysis of the polysaccharide were overcome and it was possible to identify some of the fragments in the hydrolyzate. At least six products resulted from nitrous acid deamination. Two were disaccharides, which were identified, and sequences of linked sugar units were proposed. As modification of the polysaccharide decreased the amounts of antibody precipitated by anti-pneumococcal Type I sera, the importance of the unmodified structural features in contributing to the specificity of the polysaccharide was indicated. Also, the polysaccharides of Pneumococcus Types V and XIV were subjected to intensive investigation by the Birmingham group. For the Type V intact polysaccharide, their research revealed that there were N-acetyl (but no 0-acetyl) groups and that D-glucose, D-glucuronic acid, L-fucosamine, and L-pneumosamine were present. The majority of the D-glucose and D-glucuronic acid units were linked (1-4) and (1+2), respectively. From partial acidic hydrolysis, methylation studies, and periodate oxidations, it was feasible to make reasonable deductions about the mode and sequence of the linkages of these units. By established methods, augmented at later stages by newer procedures, Pneumococcus Type XIV polysaccharide was studied to test chemically the structural predictions based on immunological studies and to gain more information about the polymer. By 1945, Stacey speculated about the possibility of a structural relationship between Pneumococcus capsular polysaccharides and those produced by other organisms. With Miss Schluchterer, he had examined the capsular polysaccharide of Rhizobium radicicolum. This polysaccharide gave a precipitin reaction in high dilution, not only with Type I11 Pneumococcus antiserum, but also mixed with antisera from other Pneumococcus types. The chemical evidence indicated that the polysaccharide resembled the specific polysaccharides of Types I and I1 Pneumococcus. A decade later, the acidic capsular polysaccharide from Azotobacter chroococcum, a soil organism, was studied. It, too, produced serological cross-reactions with certain pneumococcal specific antisera. Although the molecular structure of the polysaccharide was not established, adequate evidence was accumulated to show a structural relationship to Type 111 Pneumococcusspecific polysaccharide. This was sufficiently close to account for the Type 111 serological cross-relationship. In the late 1940s Stacey, with the able and enthusiastic assistance of Paul Kent, examined polysaccharide material from Mycobacterium tuberculosis human strain. From heat-killed cells, two stable, serologically specific polysaccharide fractions and a degraded bacterial glycogen were isolated and examined.
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The units composing the polysaccharides were defined. Both polysaccharides under examination by the methylation procedure were shown to have highly branched structures. This work confirmed and extended earlier information provided by Heidelberger and Menzel(1932), and Chargaff and Schaefer (1935) on serologically active polysaccharides from M . tuberculosis, and was a contribution to the chemistry of “tubercle glycogen.” Also, in 1949, Kent, Seibert, and Stacey reported work on an antigenic polysaccharide from tuberculin. It had chemical and serological properties very different from a known polysaccharide from tuberculin. Stacey’s investigations of microbial polysaccharides ranged over materials from numerous organisms that had been grown on a variety of media. For example, one of his many interests was luteic acid, which is a unique polysaccharide containing malonic acid residues. It was isolated in 1931 by Raistrick and his colleagues from the metabolic products of Penicillium luteum Zukal grown on D-glucose. Removal of the malonic acid residues from luteic acid left a neutral polysaccharide, luteose, which (from experiments described in 1939 by Haworth, Stacey, Raistrick, and Anderson) appeared to be essentially a chain of P-D-glucose residues, linked mainly (I-). By 1956, further results had been accumulated that indicated some degree of branching in the molecule. Later, it was found that polysaccharide fractions produced by Phteum Zukal Strain 52 could be fractionated with Cetavlon into two pure compounds. Among other polysaccharides studied were those elaborated by Neisseria perflava (starch-type polysaccharide), Polytomella coeca (a starch richer in amylopectin than most natural starches), Pseudomonas morsprunorum (Wormald) (levan), Acetohacter acetigenum (cellulose), Aerobacter aerogenes (NCTC 8172) (Klebsiella Type 164), Bacillus megaterium, Bacterium pruni, and Bacterium prunicola (polyfructoses of the levan type). In the mid-l930s, Stacey became interested in the dextran group of polysaccharides, which became one of his enthusiasms and successes. It combined his chemical and commercial interests and allied them with the idealistic side of his nature to help those suffering from injury or disease. This class of polysaccharide was well known in sugar refineries as the causative agent of “ropiness”*: it was formed from cane or beet sugar by bacteria of the Leuconostoc genus. Over many years, numerous papers were published, mainly with E. J. Bourne [Adv.Carbohydr. Chem. Biochem., 34 (1977) 1-22] and S . A. Barker as co-authors, describing the isolation, purification, properties, and structural features of dextrans. *It is perhaps ironic that, many years after his interest was first aroused, Stacey was to experience a fermentation failure owing to an unwanted dextran. He, and a large group of colleagues (potential co-tasters!), published a report of an attempt to make elderberry wine. A viscous, transparent gum, rather than a delicious drink, was produced. The gum was a typical, but unwelcome, dextran.
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Stacey always had entrepreneurial instincts, and the commercial exploitation of dextrans became one of his goals. He recognized that they could be made cheaply from sugar, in good yield, and on a large scale. With a preponderance of (l-) glycosidic linkages, they would not be attacked by beta amylase and probably could be used to replace body fluids. Although his early reasoning was sound, the project was developed and applied more rapidly in the early 1940s in Sweden. Eventually suitably degraded dextrans in 6% physiological saline found use as blood plasma substitutes. Stacey’s contributions were recognized and he received the Grand Award of U.S. National Academy of Sciences (1950) and the John Scott Memorial Medal (1969). Contemporaneously to forging ahead with modified dextrans as pharmaceutical products, Stacey and his collaborators vigorously investigated the chemistry of these substances. They showed that dextrans could be produced by a range of organisms acting on a sucrose substrate. These products were examined by conventional methylation procedures, hydrolysis, and end-group analysis, and this work (together with that of others) revealed that the products of these bacterial syntheses were macromolecules of various types. In all, the a-(1-6) linkage of the D-glucose units predominates, but some have long and virtually unbranched straight chains with a-(1-6) linkages, whereas others have branched structures in which short chains of the foregoing type are formed by (1-4) branches or (1-3) glucosidic linkages. In the dextran synthesis, the degree of branching depends to some extent on the composition of the medium. Magnesium in the medium favors the production of branches, but a granular form of the dextran is produced when the medium is deficient in magnesium and leads to difficulties in the large-scale production of dextran. Toward the end of the 1950s, the project had developed to the stage when a cell-free dextransucrase, prepared from Betucoccus urubinosaceous (Birmingham Strain), could be used for the syntheses. It was comprised of two enzymes, which, together, synthesized a highly branched dextran. Partial inactivation of one of the enzymes yielded a preparation, which then only synthesized a relatively unbranched dextran. The addition, for example, of isomaltose, maltose, or D-glucose to the enzyme system was found to decrease the production of dextran and each led to the syntheses of oligosaccharides of known structure. Barker, Bourne, and Stacey reported in 1953 a study they had completed of a unique, essentially unbranched intracellular glucan produced by Aspergillus niger Strain 152.” Originally, it was named “mycodextran.” However, examination revealed that it contained only a small proportion of (1-6) glycosidic linkages, and was composed mostly of a-(1-4) and a-(1-3) linkages, arranged alternately. As the term “mycodextran” would inevitably lead to confusion, the substance was renamed “nigeran.” This led to studies of the metabolic products of Aspergillus niger. It is interesting to speculate whether this development could be traced back to Raistrick’s influence. In a lecture in 1964 on “New Prospects “
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in the Chemistry of Micro-organisms,” Stacey contended that research on microorganisms had been devoted previously to a study mainly of intermediate metabolism. In a carefully planned program of research, Raistrick and his school had developed a more-direct chemical approach to the products of mold metabolism. Stacey foresaw the full implications of this approach, particularly for the synthesis of oligo- and poly-saccharides, and determined to explore it. Indeed, the first heteropolysaccharide to be examined in the Birmingham laboratories was varianose, a mold polysaccharide obtained by Stacey from Raistrick’s laboratory. The decision to study the transglycosylation processes occurring with A . niger (“152”) was shrewd because the organism proved to be a versatile source of new, useful compounds. The enzyme systems in growing cultures, resting cells, and in cell-free extracts were studied by Barker, Bourne, Stacey, and their co-workers. Soon, their research revealed that the enzyme system of the mold can transfer a glucosyl group from cellobiose to another cellobiose molecule, to other p-linked disaccharides, or to D-glucose-the principal new linkage being p-(1--*6), although p-( 1+2), p-(1+3), and p-( 1-4) links were also formed. Subsequently, it was shown that D- and L-xylose, L-sorbose, and N-acetyl-D-glucosamine can also function as receptors in the transfer reaction, thereby affording new, and at that time unusual, di- and oligo-saccharides. In 1959, the mold enzymes were used to prepare a pseudoaldobiouronic acid when D-glucuronic acid was used an alternative receptor during growth of A.niger 152 on a medium containing maltose and D-glucuronolactone as the sole source of carbon. By extension of this approach, hitherto inaccessible acid-labile pseudoaldobiouronic acids were made available. Initially, attempts to grow the organism on sodium acetate as the sole source of carbon were unsuccessful, but the difficulties were overcome and mannitol, arabinitol, erythritol, glycerol, maltose, and a,cx-trehalose were produced. This was a useful development because conditions were established for the incorporation of [14C] acetate, thereby making labeled polyols and disaccharides available. The medical uses of carbohydrates and the differences between carbohydrates of healthy and diseased tissues were of continual interest to Stacey, and he was a regular participant in meetings on these subjects. Heparin and hyaluronic acid were of special interest. A method, based on turbidity curves, was devised for the “fingerprinting” of the hyaluronic acid component of normal and pathological synovial fluids. It was claimed that the method was useful for the classification of synovial fluids, and for determining the effect on the fluids in patients undergoing therapy for rheumatoid arthritis, osteoarthritis, and other joint disorders. The hyaluronic acid- protein complex of the human vitreous humor was also “fingerprinted” and, for the preservation of vitreous humor, inhibition of its depolymerization was investigated. Dimethyl sulfoxide was shown to be highly effective in the storage of the cornea.
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The relationship between structure and anticoagulant activity of heparin was a conundrum that puzzled Stacey. He did not solve the problem, but demonstrated that certain structural features of heparin (for example, extensive release of amino groups) alone were not responsible for the biological activity. Among other aspects of the chemistry of disease to which contributions were as made were the synthesis of aryl 2-acetamido-2-deoxy-~-~-glucopyranosides potential anti-inflammatory and analgesic agents in rheumatoid arthritis therapy, and condensation of long-chain fatty acids with polysaccharides: the aim was to determine whether a granuloma-forming fatty acid would lead to antigens capable of conferring a protective action against the granuloma-forming action of the acid itself. Chemical investigations were undertaken of glycogen storage disease, a case of juvenile amaurotic idiocy, and with chronic bronchitis. Late in his career, with Kennedy as co-worker, a partial linkage analysis was reported for human pituitary follicle-stimulating hormone and human chorionic gonadotrophin. His fascination with bacterial polysaccharides did not preclude Stacey from being interested in other products from microbial sources. For example, he set colleagues the task of isolating, in relatively undegraded form, microbial nucleic acids. One of their first reports concerned the isolation of DNA from avirulent and virulent strains of Haemophilus pertussis. The DNAs from the two strains showed some differences in biological properties. Methods were devised for the separation, in relatively undegraded form, of RNA and DNA from, for example, M . tuberculosis, M . phlei, and Sarcena lutea. With bacterial nucleic acids becoming more available, their chemical and physical properties could be determined. The changes brought about by disaggregation of DNA by ultrasonic irradiation were studied by Overend, Peacocke, and Stacey. Changes in (i) the pattern of the titration curves, (ii) the ultraviolet absorption curves, and (iii)the viscosities of the undegraded and degraded nucleic acids were measured. The observations were interpreted in terms of the progressive rupture of inter- and intrahydrogen bonds, and then of the polynucleotide chain. It was suggested that disruption by a cavitation process should be avoided when isolating undegraded samples of nucleic acid from cells. In another series of experiments, a novel approach to the determination of nucleotide sequence was adopted by A. s. Jones, Stacey, and their co-workers. For example, when calf thymus DNA was treated with mercaptoacetic acid in the presence of zinc chloride and anhydrous sodium sulfate, it yielded aldehydoapurinic acid bis(carboxymethy1) dithioacetal. When degraded with dilute alkali, this afforded dialyzable fragments, which were separated into at least 20 components. Some were identified, including mono-, di-, and tri-nucleotides, thereby revealing that DNA contain regions of at least three linked pyrimidine nucleotides. The same procedure was applied to the DNA isolated from M . phlei:
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PAUL FINCH AND W. GEORGE OVEREND
eight compounds were identified and their proportions in the total hydrolyzate were determined. Although many of the components from the DNA of both M. phlei and calf thymus were not identified, differences between the two nucleic acids were highlighted. His work with micro-organisms led Stacey to recognize a need to put the microbiological and histological staining reactions on a firm chemical basis. Thus, in the late 1940s, with H. Henry (an eminent bacteriologist), a detailed study was made of the Gram-staining reaction. They sought to elucidate the chemical differences between those organisms stained by the basic fuchsin-iodine technique (Gram-positives) and those that do not retain the stain on being washed with alcohol (Gram-negatives), Their experiments indicated that the “dye-retaining factor” of Gram-positive organisms is a nucleoprotein located near the cell surface. An essential part of this factor could be stripped from the cell by extraction with a solution of a bile salt: a Gram-negative cytoskeleton remained. No correlation was noted between the bacteriostatic power of bile acids (and some compounds derived from cholanic acid) and their relative activities in removing the Gram-positive complex from yeast. From the extract with bile acid, a fraction was isolated that could be plated back onto the cytoskeletons (kept under reducing conditions) to restore, in large measure, the Gram-positive character of the cells. If the cell surface had been disrupted mechanically, the possibility of reconstituting the Gram complex was destroyed completely. Cells rendered Gram-negative by the action of lytic enzymes were difficult to reconstitute, unless first treated with the protein component of the Gram complex, followed by the addition of magnesium ribonucleate. Magnesium ribonucleate was shown to be in the bile acid extract of the Grampositive cells: deoxyribonucleate was not effective. The dye-retaining nucleoproteins from yeast and Chtridium welchii were examined in some detail. They were similar in general properties, but differed in their ease of dissociation into protein and nucleic acid. Both components of the yeast nucleoprotein were obtained in reasonable purity: Neither gave a positive Gram-stain. On re-forming the nucleoprotein, it again stained positive, thereby showing its importance in the staining reaction. To complement the study of the Gram-staining process and possibly to gain an insight into the behavior of organisms when acted on by antibiotics, Stacey, Webb, and A. S. Jones examined aspects of bacterial autolysis. Although they appreciated that their work did not provide a complete picture of the autolysis, they nevertheless succeeded in showing that, in the cellular disintegration, several distinct enzyme systems were involved and some of the enzymes’ characteristics were defined. Stacey also initiated a study of the widely used Dische and Feulgen staining methods. When he commenced his investigations, knowledge of the chemical basis of the tests was limited, although there was extensive literature on applications of the Feulgen reaction.
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In the Dische test (introduced in 1930 and adapted by Sevag et al. in 1940 for the detection of DNA in cellular material), a characteristic vivid blue color is produced when DNA or cell material is heated with diphenylamine under rigidly controlled conditions of acid concentration, time, and temperature. It was claimed (incorrectly) to be highly specific. The Feulgen reaction, dating from 1924, depends on the restoration of color to Schiff’s fuchsin-sulfurous acid reagent, and is less specific because any aldehyde liberated in a gentle hydrolysis of cell material will yield a positive test. Stacey and his colleagues’ contribution was to demonstrate that o-hydroxylevulinaldehyde is formed in the test and is the active reactant. They showed that it is a labile intermediate in the conversion of 2-deoxy-~-erythro-pentose(“2-deoxyribose”) (liberated from DNA) into levulinic acid. The acid was negative in the Dische test. It became clear that any substance capable of producing o-hydroxylevulinaldehyde,under the conditions used for the Dische and Feulgen reactions, will produce a positive result; to confirm the presence of DNA in cells, these tests should be supported by other evidence. When Stacey began to study color and staining reactions, the main interest of others was in the application and modification of the tests, but very little was known about the underlying chemistry. His work opened up new lines of investigation. In tandem with his studies of polysaccharides, Stacey had a research group investigating the chemistry of the unusual sugars found as components of carbohydrate macromolecules. In this context, derivatives of simple sugars, di- and trisaccharides, uronic acids, deoxy sugars, amino sugars, sugar sulfates, and phosphates were studied. In 1947, L-rhamnose was first recognized by Stacey as a constituent of Pneumococcus Type I1 specific polysaccharide. This finding was confirmed, in 1952, by Kabat et al. and in 1955 again by Stacey when 2,4- and 2,5-di-O-methyl-~rhamnose were synthesized and the former was shown to be identical with a di-0-methylrhamnose, obtained by hydrolysis of the methylated polysaccharide. This result indicated a pyranose ring structure for the rhamnose units in the polysaccharide. Announcement of the identification of D-arabinofuranose as a constituent of a polysaccharide from M . tuberculosis aroused considerable interest. The L-enantiomer had been found extensively in polysaccharides, but reports of the natural occurrence of D-arabinose had been comparatively rare. To have available reference compounds for comparison with degradation products of polysaccharides, syntheses of derivatives (particularly methyl ethers) of both D- and L-arabinose were reported in 1947. As investigations with polysaccharides of microbiological, plant, and animal origin revealed the presence in these substances of uronic acids, it became necessary to know more about the acids. Moreover, the occurrence of uronic acids in plant gums and pectic substances, and the structures of urinary
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PAUL FINCH AND W. GEORGE OVEREND
glucosiduronates- the so-called detoxification products of various chemical substances when taken by mouth-had attracted the attention of the Birmingham chemists. In the decade from 1939, convenient syntheses by essentially conventional methods of D-glucuronic, D-galacturonic, and D-mannuronic acids and their methyl ethers were reported from the Birmingham laboratories. Over a period of 20 years, Stacey investigated the chemistry of deoxy sugars. Initially, his senior collaborator was W. G. Overend, but later F. Shafizadeh [Adv. Carbohydr. Chem. Biochem., 44 (1986) 1-61 become a prominent member of the group. Starting in 1949, publications on this class of sugars appeared regularly. Stacey decided that attention should be directed first to 2-deoxy-~-ribose, the sugar component of DNA. Methods were devised to make both the D- and Ldeoxypentoses more accessible, and a convenient method to purify the sugars was developed. The properties and reactions of the sugars were defined and structures of their transformation products were established. As model compounds for the nucleoside components of DNA, N-glycosyl derivatives of 2deoxyribose were prepared and their chemical behavior was compared with that of the 0-glycosides. Of some interest was the observation (covered by patent) that a linear polymer is formed by the elimination of methanol between units when methyl 2-deoxyglycofuranosides are slowly heated or superheated. The preparation and hydrolytic stabilities of phosphate esters of the 2-deoxypentose were studied. The program was widened to include other 2-deoxy sugars, particularly 2deoxy-D-arabino and -o-lyxo-hexose. An “in-depth” study of the glycal procedure for the preparation of 2-deoxy sugars led to improvements, but also revealed a reaction more complex than previously appreciated: It was shown that derivatives of furan and pyran were also products of the reaction. By this program of research, knowledge of the chemistry of 2-deoxy sugars was expanded considerably and significantly. In the 1960s, the direction of the work altered, and with A. B. Foster, J. M. Webber, and J. S . Brimacombe, Stacey’s attention became focused on the (then) unusual sugar components of antibiotics and other medicinal agents. From a study of the alkaline degradation of desosamine (a modified sugar found in a group of macrolide antibiotics), the absolute configuration at C-5 of the sugar was established. When considered in conjunction with other evidence, it became was being handled. Then, clear that a 3,4,6-trideoxy-3-dimethylamino-~-hexose a configurational correlation of desosamine with chalcose was completed by a route that provided further confirmation of the deduced configurational assignments and indicated that chalcose was 4,6-dideoxy-3-O-methyl-~-xylo-hexose. Likewise, the alkaline degradation of mycaminose afforded results indicative of the erythro configuration at C-4-C-5 of the modified hexose. This evidence, together with results from other research groups, pointed to the structure of
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mycaminose as being 3,6-dideoxy-3-dimethylamino-~-~-glucose. Syntheses confirmed these assignments. For example, in rapid succession, successful syntheses were reported of mycinose (6-deoxy-2,3-di-O-methyl-~-allose), javose (6-deoxy-2-O-methyl-~-allose),6-deoxy-3-O-methyl-~-allose,chromose A (2,6dideoxy-4-O-methyl-~-lyxo-hexose), derivatives of L-perosamine (4-amino-4,6dideoxy-L-mannose), and mycaminose. Some novel methods were introduced in these syntheses, and glycosulose derivatives were featured as intermediates. Regular publications of high quality on amino sugar chemistry came from the Birmingham laboratories. Some of the projects have already been noted, namely the syntheses of antibiotic components, but many papers were concerned with the chemistry of the amino sugars found in polysaccharides. At the outset, it was deemed advisable to make some amino sugars more accessible. A method was described in 1944 for the preparation of “chondrosamine” (galactosamine) hydrochloride, which (at that time) was much less accessible than glucosamine. The interest in this 2-amino sugar arose from its occurrence in the chondroitin sulfate of cartilaginous tissue. Chrondroitin sulfate was prepared by Stacey from the cartilage of bovine nasal septa and converted into chondrosamine hydrochloride in good yield. Soon after, by an elegant series of experiments, James, Smith, Stacey, and Wiggins, completed a constitutional synthesis of “chondrosamine.” was cleaved with ammonia to afThe epoxide in 1,6:2,3-dianhydro-P-~-talose ford two amino- 1,6-anhydro-deoxyhexoses.One of these was also obtained when 1,6:3,4-dianhydro-P-~-talose was heated with ammonia, showing that it was 3-amino- 1,6-anhydro-3-deoxy-P-~-talose. From knowledge of the mode of scission of epoxides, the other product was 2-amino- 1,6-anhydro-2-deoxy-PD-galactose. When it was hydrolyzed with acid, it afforded 2-amino-2-deoxyD-galactose hydrochloride, identical to chondrosamine hydrochloride, prepared from bovine tracheal cartilage. Thereafter, numerous syntheses of amino sugars and aspects of their chemistry were described, with Brimacombe, Foster, Horton, and Webber as Stacey’s main collaborators. In the syntheses, they incorporated a range of methods; for example: cleavage of epoxides with ammonia or azide ion; displacements of sulfonyloxy groups with nitrogen-containing nucleophiles; oximation of glycosuloses, followed by reduction of the oxime; conventional chain-shortening, as in the preparaand the addition of iodine azide to 5,6-unsatution of 3-amino-3-deoxy-~-lyxose; rated sugars. The nitrogen-containing sugar derivatives so obtained were converted into amines by conventional methods, but in the course of the work, observations useful in devising new syntheses were recorded: for example, the use (then novel in carbohydrate chemistry) of the methyl ether group as a blocking agent and its removal with boron trichloride. In contemplating the use of alkaline reagents, it was found that care needed to be exercised when selecting the amine-protecting group if free hydroxyl groups are also present in the molecule.
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L-Fucosamine was found as a constituent of Pneumococcus Type V capsular polysaccharide and as a constituent of the mucopolysaccharides (glycosaminoglycans) of certain enteric bacteria: A new synthesis was devised to make the amino sugar more available. Foster et al. examined (i) the nitrite deamination of a- and P-D-glucosamine hydrochloride and (ii) the acidic hydrolysis of a series of glucosamine derivatives to obtain information likely to be of value in investigation of glycosaminoglycans and colorimetric determination of D-glucosamine in glycosaminoglycan hydrolyzates. In the deaminations, similar mixtures of substances were formed, with 2,5-anhydro-o-mannose (chitose) as the main product, but at very different rates. Stacey and his group realized that the influence of the glycosidic center on the rate of deamination might be of value in establishing the configuration of the glucosaminidic linkage in some glycosaminoglycans. They examined whether this was so for heparin, for which the a configuration of the glucosaminidic linkage had been suggested on the basis of optical rotation measurements. Heparin was N-desulfated to yield +-heparin and its rate of deamination was measured. The deamination rates of methyl a-D-glucosaminide and +-heparin were discovered to be closely similar; this was considered as confirmatory evidence for aglucosaminidic linkages in heparin. In I96 1, 2-deoxy-2-sulfoamino-~-glucose (D-glucosamine N-sulfate) was synthesized and, in a model experiment, the acidlability of the N-sulfate residue was compared with that of groups in heparin. To gain an insight into the likely hydrolytic behavior of sulfated simple sugars and polysaccharides, Brimacombe, Foster, Hancock, Overend, and Stacey carried out a rigorous set of experiments with the cyclic sulfates of cyclohexane cisand trans-1,2-diol as model compounds. The results were interpreted on the reasonable assumption that, in all cases, the cyclic sulfates initially afford a diol monosulfate. Examples of both S -0 and C - 0 bond cleavage were encountered. A qualitative reaction mechanism was proposed for use as a working hypothesis for the hydrolysis of sugar sulfates. The chemical and enzymic synthesis of di-, tri-, and oligo-saccharides was another of Stacey’s interests. In 1946, he and Mrs. Gilbert reported chemically simple, constitutional syntheses of cellobiose, gentiobiose, and nonreducing sugars of the trehalose type. Transglycosylations with microbial enzymes were exploited as a facile route to new oligosaccharides for comparison with products obtained in partial hydrolyzates of higher oligosaccharides and polysaccharides. They were also used to prepare I4C-labeleddisaccharides from labeled monosaccharides. In 1960 and 1962, with S. A. Barker, he published in two monographs, “Polysaccharides of Micro-organisms” and “Carbohydrates of Living Tissues,” the results of the extensive researches on polysaccharides carried out at Birmingham and elsewhere. Besides research already outlined, Stacey undertook other work, some of which was distinct from carbohydrate chemistry. This relates to his contributions to radiation chemistry, analysis, organofluorine chemistry, and soil chemistry.
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Early in the 1950s, Stacey was successful in his negotiations to have a 6oCo source of y-rays installed in his laboratory. Then, in collaboration with Barker and Bourne, a series of investigations of the effects of y-radiation on saccharides was started. Both polymer formation from simple sugars and the degradation of polysaccharides were studied. Although rarely the originator of a new technique, Stacey always had an eye for technical developments likely to be applicable in carbohydrate chemistry: Even near retirement, he was contributing articles, for example, on “Technique Aspects of Carbohydrates” and “Modern Methodology of Structural Polysaccharide Chemistry.” Colleagues were encouraged to adopt and adapt new methods, particularly for separatory techniques and the analyses of mixtures of sugars. Paper chromatography was soon in extensive use in his laboratory, and problems encountered in the separation and detection of sugars in biological fluids containing nitrogenous matter (such as diabetic urines) were resolved. Through the initiative of Foster, with Stacey’s support, the behavior of sugars and their derivatives on paper ionophoresis in alkaline borate (and other buffers) was delineated by the mid- 1950s. Thereafter, the method was widely used to separate sugar mixtures. The ways in which borate ions interact with sugars stimulated discussion about the conformations adopted by sugars in solution. An alternative rapid method, complementary to the borate procedure, was to convert the saccharides on the paper into their N-benzyl glycosylamine derivatives, then to place a charge on the nitrogenous derivatives by using an acid medium during electrolysis. This method was satisfactory for separation of a homologous series of reducing oligosaccharides. Stimulated by the renewed interest in the analysis and study of the oligosaccharide constituents of glycoproteins, perhaps belatedly, the electrophoretic method has recently reappeared in commercial form. Separations of polysaccharides by fractionation on a preparative scale were also examined. Stemming from earlier work in his laboratory on the isolation of acidic polysaccharides by precipitation as their insoluble “Cetavlon” salts, Stacey and coworkers showed that it was possible to fractionate neutral polysaccharides by selective precipitation with “Cetavlon” after the formation of borate complexes. New, and more rapid acquisition of information about the sites and stereochemistry of the linkages of the units in oligo- and poly-saccharides was always being sought. Kenner and Richards demonstrated in 1954 the high degree of specificity in the saccharinic acids formed during the alkaline degradation of polymeric carbohydrates by lime-water. In 1967, Stacey et al. published a report of a re-examination of the saccharinic acid assay, and its potential for the linkage analysis of carbohydrates. Where others had been unsuccessful, Stacey ’s group was able to assay isosaccharinic [from (1-4) linked aldoses], metasaccharinic [from (1-3) linked aldoses], and saccharinic acids on a microgram scale. The methods could be used to monitor the production of such acids during the alkalimediated “peeling” reaction of oligosaccharides. These methods of assay,
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PAUL FINCH AND W. GEORGE OVEREND
coupled with determination of the formaldehyde produced, following periodate oxidation of the equilibrium degradation mixture, were proposed for use in linkage analysis of oligosaccharides containing hexoses or hexuloses. Another approach to polysaccharide structure was developed in collaboration with D. H. Whiffen. The infrared spectra of numerous carbohydrates were measured and, thereby, a powerful means for the comparison of carbohydrates became available. It was possible to assign anomeric configurations to sugars by interpreting their spectra over the frequency range 730-960 cm-’, no matter whether they are reducing sugars, methyl glycosides, or polysaccharides. Furthermore, an indication could be obtained of the position of the glycosidic linkages in a glucan. Following Haworth’s lead in the 1920s, Stacey soon appreciated that an analytical subdepartment was invaluable in serving the needs of his research teams. He supported and fostered analytical chemistry wholeheartedly and, in doing so, showed considerable foresight. He cooperated in studies for the analysis of carbohydrates, for example, a new method for the quantitative microscale determination of the sulfate content of carbohydrates, the determination of uronic acids in 20-mg samples, and the automated determination of formaldehyde in periodate oxidations of carbohydrates and amino acids. When he became head of department, at a time when the subject was grossly neglected in other universities in the United Kingdom, Birmingham had a flourishing School of Analytical Chemistry, which, with his encouragement, was to become world famous. Although carbohydrate chemistry was his main personal research interest, he was influential in founding fluorine chemistry as a significant chemical discipline in the United Kingdom. Many of those he introduced to the subject moved on to establish other research centers on fluorine chemistry in the United Kingdom. Stacey became involved with fluorine chemistry during World War 11. Haworth had associated his department with the United Kingdom’s “Tube Alloys” atomic research project. At first, he was concerned with uranium compounds, including the hexafluoride. As the project developed, they began to investigate fluorocarbons, which were needed to prepare fluids, oils, and greases so that the highly reactive uranium hexafluoride could be handled and its isotopic forms separated. This investigation was directed by Drs. Stacey and Fred Smith [Adv.Carbohydr. Chem. Biochern., 22 (1967) 1-10]. When hostilities ceased, a small team was formed to pursue more general research on organofluorine chemistry. Over time the team was expanded and ultimately became a very large group. When Smith departed to the United States, Stacey took sole charge of the team, but throughout he relied on Professor J. C. Tatlow for detailed direction of the work. Research that Stacey was particularly associated with in the earlier years, which bridged fluorine and carbohydrate chemistry, included studies of trifluoroacetic acid and its anhydride. These were among the first organic fluorides to
MAURICE STACEY
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be used generally in organic chemistry -usage that since has been greatly extended. Unsymmetric anhydride species were determined to be the active agents. Carbohydrates were trifluoroacetylated, which was a useful way of protecting hydroxyl groups; when required the ester function could be removed easily. Related to his interests in analytical chemistry, fluorine analysis became a specialty area. The nucleic acid team worked jointly with Dr. P. L. Coe on fluorine-containing nucleic acid derivatives. Stacey frequently lectured on the potential of a sugar-based chemical industry, and it was natural that he should maintain an interest in the chemistry of agriculture and soil. However, apart from a paper with Haworth and Pinkard in 1946, a systematic involvement with soil chemistry did not occur until the 1960s. Then, M. H. B. Hayes joined Stacey’s department and was encouraged to begin yet another area of chemical achievement. As time passed, the balance of Stacey’s interests changed: He became less involved with the close direction of research and more with administration. Moreover, his chemical work had become far too wide for him to have a detailed knowledge of all of it. He retained his strategic foresight and, always, could advise how best to develop a project. He had an ability to join forces with and motivate his colleagues, who carried forward the detailed work. Also, he was able to recall, with uncanny accuracy and perception, the ability and character of each of the many collaborators, with whom he had been associated during his career. He took an enduring interest in promoting the welfare and careers of his students and colleagues. The biographical articles that he wrote demonstrate his insight into the personalities of those he knew. A raconteur of note, he had a rich collection of anecdotes about major figures in the carbohydrate world, in particular of‘Haworth and his stern regime. He was always in demand as a speaker, and his infectious enthusiasm communicated science as effectively to lay audiences as to experts. Stacey’s success brought him many honors and he was the recipient of awards both from the United Kingdom and abroad. The Meldola Medal, awarded to him at the early age of 26, and the Inaugural Haworth Medal in 1970 were especially gratifying to him. He gave many prestigious lectures and served on numerous scientific committees and boards of governors. He was vice-president of the Chemical Society on four occasions and president of its Perkin Division. He was elected F.R.S. in 1950 and appointed C.B.E. in 1966. He was a sociable man whose friendship, laced with humor, was evident to all: an entertaining companion with a stockpile of amusing stories to suit any occasion. To sum up his life, if example is “The School of Mankind,” then Maurice Stacey ran a good school. PAULFINCH W. GEORGEOVEREND
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PAUL FINCH AND W. GEORGE OVEREND
APPENDIX
This list contains the titles of papers that carry M. Stacey’s name as author. It does not include those published independently by his colleagues in the University of Birmingham laboratories. “Walden Inversion in the a-Glucoheptose Series. The Preparation of New Derivatives and the Determination of the Structure of Methyl-a-glucoheptoside,” W. N. Haworth, E. L. Hirst, and M. Stacey, J . Chem. Soc., (1931) 2864-2872. “Methylation of Monocarboxylic Acids Derived from Aldoses. Structure of Pentamethyl a-Glucoheptono-y-lactone,” W. N. Haworth, E. L. Hirst, and M. Stacey, J. Chem. Soc., (1932) 2481-2485. “Synthesis of d- and of I-Ascorbic Acid and of Analogous Substances,” R. G., Auk, D. K. Baird, H. C. Canington, W. N. Haworth, R. Herbert, E. L. Hirst, E. G. V. Percival, F. Smith, and M. Stacey. J. Chem. Sac., (1933) 1419-1423. “Ascorbic Acid and Synthetic Analogues,” D. K. Baird, W. N. Haworth, R. W. Herbert, E. L. Hirst, F. Smith, and M. Stacey, J . Chem. Soc., (1934) 62-67. “Studies in the Biochemistry of Micro-organisms. Part XXVI. The Metabolic Products of Penicillium charlesii, G. Smith,’’ P. W. Clutterbuck, W. N. Haworth, H. Raistrick, G. Smith, and M. Stacey, Biochem. J., 28 (1934) 94-110. “Polysaccharides Synthesized by Micro-organisms. 1. The Molecular Structure of Mannocaralose Produced from Glucose by PeniciNium charlesii G. Smith,” W. N. Haworth, H. Raistrick, and M. Stacey, Biochem. J., 29 (1935) 612-621. “Polysaccharides Synthesized by Micro-organisms. 11. The Molecular Structure of Varianose Produced from Glucose by Penicillium varians G. Smith,” w . N. Haworth, M. Raistrick, and M. Stacey, Biochem. J.,29 (1935) 2668-2678. “Polysaccharides Synthesized by Micro-organisms. 111. The Molecular Structure of Galactocarolose Produced from Glucose by Penicillium charlesii G. Smith,” W. N. Haworth, H. Raistrick, and M. Stacey, Biochem. J., 31 (1937) 640-644. M. Stacey, S. W. Challinor, and H. Raistrick, Proc. In!. Congr. Microbid., (1937) 356. “The ImmunisLng Potency of Antigenic Components Isolated from Different Strains of Bact. typhosum,” W. W. C. Topley, H. Raistrick, J. Wilson, M. Stacey, S. W. Challinor, and R. 0. J. Clark, Lancet, I (1937) 252-256. “Immunising Antigens of Bacteria,” M. Stacey, Lancet, 1 (1937) 274-275. “Enzyme Formation and Polysaccharide Synthesis by Bacteria. 111. Polysaccharides Produced by Nitrogen-fixing Organisms,” W. A. Cooper, W. D. Daker, and M. Stacey, Biochem. J., 32 (1938) 1752-1758. “A Note on the Dextran Produced from Sucrose by Befacoccus arubinosaceous Haemolyticus,” M. Stacey and E R. Youd, Biockem. J.. 32 (1938) 1943- 1945. “Investigation of a Polysaccharide Produced from Sucrose by Beta-Bacterium wermiforme‘ (WardMayer),” W. D. Daker and M. Stacey, Biochem. J.. 32 (1938) 1946- 1952. “The Polysaccharide Produced from Sucrose by Leuconosroc dextrunicum,” S. Peat, M. Stacey, and E. Schliichterer, Narure, 141 (1938) 876.
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“Polysaccharides. Part XXIX. Constitution of the Dextran Produced from Sucrose by Leuconostoc dexfranicum (Betacoccus arabinosaceous Haemolyticus),” S. Peat, E. Schluchterer, and M. Stacey, J. Chem. Soc., (1939) 581-585. “Polysaccharides. Part XXX. The Polysaccharide Produced from Sucrose by Befubucterium vermiformi (Ward-Mayer),” W. D. Daker and M. Stacey, J. Chem. Soc., (1939) 585-587. “The Synthesis of Uronic Acids,” M. Stacey, J. Chem. Soc., (1939) 1529- 1531 “Polysaccharides. Part XXXV. Hydrocellulose,” H. C. Carrington, W. N. Haworth, E. L. Hirst, and M. Stacey. J . Chem. SOC., (1939) 1901-1904. “Polysaccharides Synthesized by Micro-organisms. IV. The Molecular Constitution of Luteose,” C. G. Anderson, W. N. Haworth, H. Raistrick, and M. Stacey, Biochem. J . , 33 (1939) 272-279. “Sulfonamide Drugs and P neumucoccus Capsular Polysaccharides,” M. Stacey and E. Schluchterer, Nature, 143 (1939) 724. “The Nature of the Carbohydrate Residue in Ovomucoid. Part I. The Glucosamine Constituent,” M. Staceyand J. M. Woolley,J. Chem. Soc.. (1940) 184-191. “Polysaccharides. Part XXXIX. The Constitution of Certain Levans Formed by Bacterial Action,” R. R. Lyne, S. Peat, and M. Stacey,J. Chem. Soc., (1940) 237-241. “The Nature of the Carbohydrate Residue in Ovomucoid. Part 11,” M. Stacey and J. M. Woolley, J. Chum. Suc., (1942) 550-555.
“Enzymatic Production of Bacterial Polysaccharides,” M. Stacey, Nafure. 149 (1942) 639. “Mucopolysaccharides and Related Substances,” M. Stacey, Chem. Ind. (London), (1943) 110- 112. “Histochemistry of the Gram-staining Reaction for Micro-organisms,” H. Henry and M. Stacey, Nature, 151 ( 1943) 67 1. “The Epimerisation of Some Dimethylene Saccharic Acids and Their Derivatives,” W. N. Haworth, W. G. M. Jones. M. Stacey, and L. E Wiggins, J . Chenz. Soc., (1944) 61 -65. “Synthesis of Uronic Acids. Part 11. 2:3:4-Trimethyl Derivatives of Mannuronic, Glucuronic, and Galacturonic Acids,’’ F. Smith, M. Stacey, and P. I. Wilson, J. Chem. Soc.. (1944) 131 - 134. “Derivatives of Chondrosamine.” M. Stacey, 1.Chem. Soc., (1944) 272-274. “Synthesis of Uronic Acids. Part 111. d-Mannuronic Acid.” M. Stacey and P. I. Wilson, J . Chem. Soc., (1944) 587-588. “New Prospects in the Chemistry of Micro-organisms,” M. Stacey, J . Proc. R. Insf. Chem., (1944) 159-160. “Chemistry of Tissues. I. Chondroitin from Cartilage,” H. G. Bray, J. E. Gregory, and M. Stacey, Biochem. J., 38 (1944) 142-146. “Enzyme Formation and Polysaccharide Synthesis by Bacteria. 2. Polysaccharide Formation by Rhizobiun radicicolum Strains,” H. G. Bray, E. Schluchterer, and M. Stacey, Biochem. J., 38 (1944) 154- 156. “Substrates for Hyaluronidase,” J. Madinaveitia and M. Stacey, Biochem. J., 38 (1944) 413-417. “A Crystalline Serum Mucoprotein with High Cholinesterase Activity,” R. Bader, F. Schultz, and M. Stacey, Nafure, 154 (1944) 183-184.
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“Recognition of Renal Calculi by Chemical Methods and X-ray Diffraction Patterns,” J. A. Barclay, W. T. Cooke, M. Stacey, A. D. Booth, and P. W. Kent, J . Physiol., 103 (1944) 24P.
“The Capsular Polysaccharide of Rfiizobium radicirolum,” E. Schliichterer and M. Stacey. J. Chem. SOC.,(1945) 776-783. “A Constitutional Synthesis of Chondrosarnine,” S. P. James, F. Smith, M. Stacey, and L. F. Wiggins, Nature, 156 (1945) 308-309. “Nature of the Gram-positive Complex in Micro-organisms,’’ H. Henry, M. Stacey, and E. G. Teece, Nature, 156 (1945) 720. “Histochemistry of the Gram-staining Reaction for Micro-organisms,’’ H. Henry and M. Stacey, Proc. R. Soc. Ser. B , 133 (1946) 391-406. “A Constitutional Synthesis of Cellobiose and Gentiobiose,” V. E. Gilbert, F. Smith, and M. Stacey, J . Chem. Soc., (1946) 622-625. “The Action of Alkaline Reagents on 2:3-1:6- and 3:4- 1:6-Dianhydro-P-talose. A Constitutional Synthesis of Chondrosamine and other Amino-Sugar Derivatives,” S. P. James, F. Smith, M. Stacey, and L. F. Wiggins, J . Chem. Soc., (1946) 625-628. “Tetra Acetyl Glucosone Hydrate. A Novel Route to the Syntheses of Analogues of Ascorbic Acid and a Possible Mechanism for the Transformation of Hexoses into Kojic Acid,” M. Stacey and L. M. Turton, J . Chem. Soc., (1946) 661 -664. “Basic Derivatives of Cholane and Norcholane,” S. P. James, F. Smith, M. Stacey, and M. Webb, J. Chem. Soc., (1946) 665-670. “Chemistry of Tissues. 2. Polysaccharides Showing Blood Group A Specificity and the Nature of the Constituent Units of the Stable Carbohydrate Residue of the A Substance from Pepsin,” H. G. Bray, H. H. Henry, and M. Stacey, Biochem. J . , 40 (1946) 124-130. “Chemistry of Tissues. 3. Blood Group Substances from Human Gastric Contents,” H. G. Bray, H. Henry, and M. Stacey, Biochem. J . , 40 (1946) 130- 134. “Chemistry of the Feulgen and Dische Nucleal Reactions,” M. Stacey, R. E. Deriaz, E. G. Teece, and L. F. Wiggins, Nature. 157 (1946) 740-742. “Function of Bacterial Polysaccharides in Soil,” W. N. Haworth, F. W. Pinkard, and M. Stacey, Nafure. 158 (1946) 836-837. “The Chemistry of Mucopolysaccharides and Mucoproteins,” M. Stacey, Adv. Carbohydr. Chem., 2 (1946) 161-201. “Contribution to a Symposium on Bacterial Nucleic Acids and Nucleoproteins,” M. Stacey, SOC,Exp. Biol. Med., 1 (1946) 86-100. W. N. Haworth, M. Stacey and P. W. Kent, Absfr.Am. Chem. Soc.. Meeting, Chicago, (1946) 5R. “The Chemistry of Some Cellular Constituents,” M. Stacey, J . Imp. Coll. Chem. Soc., 2s (1946) 38-41: Sci.J. R . Coll. Sci., 16 (1946). “Studies on the Antibacterial Properties of the Bile Acids and Some Compounds Derived from Cholanic Acid,” M. Stacey and M. Webb, Proc. R. Soc., Ser: B , 134 (1947) 523-537. “Macromolecules Synthesised by Micro-organisms,’’ (Tilden Lecture delivered before the Chemical Society on December 6, 1946 at Burlington House and on January 17, 1947 at Cambridge), M. Stacey,J. Chem. Soc., (1947) 853-864.
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“Some Derivatives of D-Galacturonic Acid,” J. K. N. Jones and M. Stacey, J. Chem. SOC.,(1947) 1340- 1341. “Synthesis of Some Derivatives of J . Chem. Soc., (1947) 1341-1344.
D-
and L-Arabinose,” J. K. N. Jones, P. W. Kent, and M. Stacey,
“Aspects of Immunochemistry,” M. Stacey, Quart. Rev. Chem. Soc., 1 (1947) 179-247 “The Constitution of a Specific Somatic Polysaccharide from M . tuberculosis (Human Strain),” N. Haworth, P. W. Kent, and M. Stacey,J. Chem. Soc., (1948) 121 1-1220. “The Constitution of a Lipoid-bound Polysaccharide from M . tuberculosis (Human strain),” N. Haworth, P. W. Kent, and M. Stacey, J . Chem. Soc., (1948) 1220-1224. “Structure of the Dextran Synthesised from Sucrose by a New Strain of Betacoccus arubinosaceous,” M. Stacey and G. Swift,J. Chem. Soc., (1948) 1555- 1559. “The Constitution of a Levan Produced from Sucrose by Pseudomonas mom-prunorum (Wormald),” V. E. Gilbert and M. Stacey,J. Chem. SOC.,(1948) 1560-1561. “Some Physical Properties of the Specific Polysaccharides from the Q p e s 1, I1 and 111 Pneumococcus,” B. R. Record and M. Stacey, J . Chem. Soc., (1948) 1561- 1567. “Some Components of the Lytic System of Gram-positive Micro-organisms,” M. Stacey and M. Webb, Nature, 162 (1948) 11. “The Chemistry of the Immunopolysaccharides,” N. Haworth and M. Stacey, Ann. Rev. Biochem., 17 (1948) 97- 1 14. “Sugars,” M. Stacey. Rep. Progr. Appl. Chem.. XXXIII (1948) 504-519. “The Polysaccharides of Mycobacterium ruberculosis,” M. Stacey and P. W. Kent, Adv. Cat-bohydr. Chem.. 3 (1948)311-336. “A Contribution to the General Discussion on ‘Antibiotic Activity of Growth Factor Analogues’,’’ (Meeting held on June 17, 1948), M. Stacey, Proc. R. Soc., Ser. B , 136 (1949) 145-181. “Deoxy-sugars. Part I. The Dische Reaction for 2-Deoxypentoses,” R. E. Deriaz, M. Stacey, E. G. Teece, and L. F. Wiggins, J . Chem. Soc., (1949) 1222- 1232. “Deoxy-sugars. Part 11. Synthesis of 2-Deoxy-~-riboseand 3-Deoxy-D-xylose from D-Arabinose,” P. W. Kent, M. Stacey, and L. F. Wiggins,J. Chem. SOC.,(1949) 1232-1235. “Deoxy-sugars. Part 111. Methanesulphonyl Derivatives of o-Arabinose,” W. G. Overend and M. Stacey,J. Chem. SOC.,(1949) 1235-1238. “Deoxy-sugars. Part IV. A Synthesis of 2-Deoxy-D-ribose from o-Erythrose,” W. G. Overend, M. Stacey, and L. F. Wiggins, J . Chem. SOC.,(1949) 1358-1363. “Deoxy-sugars. Part V. A Re-investigation of the Glycal Method for the Synthesis of 2-Deoxy-D- and +ribose,” R. E. Deriaz, W. G. Overend, M. Stacey, E. G. Teece, and L. F. Wiggins, J . Chem. SOC., (1949) 1879-1883. “Methanesulphonyl Derivatives of D-Galactose,” A. B. Foster, W. G. Overend, M. Stacey, and L. F. Wiggins, J . Chem. Sor., (1949) 2542-2546, “Deoxy-sugars. Part VI. The Constitution of p-Methyl-2-deoxyl-~-ribopyranoside and ap-Methyl-2deoxy-L-ribofuranoside,”R. E. Deriaz, W. G. Overend, M. Stacey, and L. F. Wiggins, J . Chem. SOC., (1949) 2836-2841.
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“Deoxy-sugars. Part VII. A Study of the Reactions of Some Derivatives of 2-Deoxy-o-glucose,” W. G. Overend, M. Stacey, and J . Stanik,J. Chem. Soc., (1949)2841-2845. “Deoxy-sugars. Part VIII. The Constitution of a~-Methyl-2-deoxy-~-glucofuranoside,” I. W. Hughes, W. G. Overend, and M. Stacey, J . Chem. Soc., (1949)2846-2849. “Studies on Trifluoroacetic Acid. Part I. Trifluoroacetic Anhydride as a Promotor of Ester Formation between Hydroxy-Compounds and Carboxylic Acids,” E. J. Bourne. M. Stacey, J. C. Tatlow, and J. M. Tedder, J. Chem. Soc., (1949)2976-2979. “The a-and the p-Form of 2.3:4,6-Tetra-acetyl-D-galactopyranoseAnilide,” K. Butler, F. Smith, and M. Stacey, J. Chem. Soc., (1949)3371-3374. “Deoxy-sugars, Parts V, VI and VII,” R. E. Deriaz, W. G. Overend, M. Stacey, J. Stansk, E. G. Teece, and L. F. Wiggins, Chem. Ind. (London),(1949)466-467. “The Structure of Sugar Anilides,” F. Smith, K. Butler, W. G. Overend, and M. Stacey, Chem. Ind. (London), ( 1949)55 1 . “The Feulgen Nucleal Reaction. Acid Degradation of Sperm Deoxynucleic Acid, Mechanism of the Feulgen Nucleal Reaction,” Chong-fu Li, W. G. Overend, and M. Stacey, Nature, 163 (1949) 538-540. “Fluorine and its Compounds,” M. Stacey, Nature, 164 (1949)642. “A General Method of Esterification using Trifluoracetic Anhydride,” M. Stacey, E. I. Bourne, J. C. Tatlow, and J. M. Tedder, Nature, 164 (1949)705. “Studies on the Autolytic Systems of Gram-positive Micro-organisms. I The Lytic System of Staphylococci,” A. S. Jones, M. Stacey, and M. Webb, Biochim. Biophys. Acra. 3 (1949)383-399. “An Antigenic Polysaccharide, ‘Polysaccharide 11,’ Isolated from Tuberculin,” Florence B. Seibert, M. Stacey, and P. W. Kent, Biochim. Biophys. Acta, 3 (1949)632-640. “Studies on the Gycogen of M . tuberculosis (Human Strain),” P. W. Kent and M. Stacey, Biochim. Biophys. Acta, 3 (1949)641-647. “Blood Group Polysaccharides,” H. G. Bray and M. Stacey, Adv. Carbohydr: Chem., 4 (1949) 37-55. The Nature of the Bacterial Surjace. M. Stacey, Blackwell: Oxford, (1949).
“Structure and Synthesis in the Group of Deoxy-sugars,” W. G. Overend and M. Stacey, Abstr. 1st Int. Congr. Biochem., (1949). “Improvements in or Relating to the Production of Trifluoroacetic Acid,” W. N. Haworth, M. Stacey, and E. V. Appleton, Brit, Pat., (1949)No 625098. “F. E. Whitmore 1923-1949,”M. Stacey. J. Chem. Sac.. (1950)440-441. “Deoxy-sugars. Part IX. Some Properties and Reactions of 2-Deoxy-o-galactose,” W. G. Overend, F. Shafizadeh, and M. Stacey, J. Chem. Soc.. (1950)671-677. “Deoxy-sugars. Part X. Some Methanesulphonyl and Toluene-p-sulphonyl Derivatives of &-Ethyl2:3-dideoxy-o-glucoside,”S. Laland, W. G. Overend, and M. Stacey, J. Chem. Soc., (1950) 738-743. “Deoxy-sugars. Part XI. Further Observations on the Dische Reaction of 2-Deoxypentoses,” W. G. Overend, F. Shafizadeh, and M. Stacey, J. Chem. Soc., (1950)1027- 1029.
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“Deoxy-sugars. Part XII. Experiments with the 0- and N-Glycosides of Some Deoxy-sugars,” K. Butler, S. Laland, W. G. Overend, and M. Stacey, .I. Chem. Soc., (1950) 1433- 1439. “The Composition of the Polysaccharide Synthesised by Polytonzella coeca,” E. J. Bourne, M. Stacey, and I. A. Wilkinson, J. Chem. Soc.. (1950) 2694-2698. “The Structure of the Starch-like Polysaccharide Synthesised from Sucrose by Neisseria peflava,” S. A. Barker, E. J. Bourne, and M. Stacey, J . Chem. Soc.. (1950) 2884-2887. “Chemistry of the Cell and its Nucleus,’’ M. Stacey, Nature, 166 (1950) 771. “A Review of Boron Tryuoride and its Derivatives (By H . S . Booth and D. R. Martin, J. Wiley and Sons Inc.: New York, 1949):’ M. Stacey,J. R . Inst. Chem., 74 (1950) 257-258. “Synthetic Substances of the Polysaccharide Type,” M. Stacey and W. G. Overend, US.Pat., (1950) NO 2649421, 1-4. “Bacterial Macromolecules. I. The Isolation of Deoxyribonucleic Acid from Virulent and Avirulent Strains of Haemophilus perfussis,” W. G. Overend, M. Stacey, M. Webb, and J. Ungar, Paper presented at A. G. M., Soc. Gen. Microbiol., April 5 , 1950. “Structure and Synthesis in the Group of Deoxy-sugars,” W. G. Overend and M. Stacey, J . Sci. Food Agric., 6 (1950) 168-171. “Some Effects of the Ultrasonic Irradiation of Deoxyribonucleic Acids,” S . Laland, W. G. Overend, and M. Stacey, Research, 3 (1950) 386. “Synthesis of Trehalose-type Disaccharides,” V. E. Sharp and M. Stacey, J . Chem. Soc., (1951) 285 -288. “Studies of Trifluoroacetic Acid. Part 111. The Use of Trifluoroacetic Anhydride in the Synthesis of Aromatic Ketones and Sulphones,” E. J. Bourne, M. Stacey, J . C. Tatlow, and J. M. Tedder, J . Chem. SOC.,(1951)718-720. “Studies of Trifluoroacetic Acid. Part IV. The Use of 4:6-Benzylidene Trifluoroacetyl Methyl-wDglucopyranoside in the Synthesis of 2- and 3-Substituted Glucoses,” E. J. Bourne, M. Stacey, (Mrs.) C. E. M. Tatlow, and J. C. Tatlow, J . Chem. Soc., (1951) 826-833. “Deoxy-sugars. Part XIV. A Further Contribution to the Chemistry of 2-Deoxy-D-galactose,” A. B. Foster, W. G. Overend, and M. Stacey,J. Chem. Soc., (1951) 974-979. “Deoxy-sugars. Part XV. D-Galactose-3 and -6 Phosphoric Acids and their 2-Deoxy-analogues,” A. 3. Foster, W. G. Overend, and M. Stacey, 1.Chem. Soc., (1951) 980-987. “Deoxy-sugars. Part XVI. A Study of the Stabilities of Some Phosphoric Acid Derivatives of D-Galactose and 2-Deoxy-o-Galactose,” A. B. Foster, W. G. Overend, and M. Stacey, J . Chem. Soc., (1951) 987-991. “Deoxy-sugars. Part XVII. An Investigation of the Glycal Method for the Preparation of Derivatives of 2-Deoxy-~-ga~actose,” W. G. Overend, F. Shafizadeh, and M. Stacey, J . Chem. Soc., (1951) 992-993. “Deoxy-sugars. Part XVIII. Synthesis of an Oligosaccharide by the Thermal Condensation of CKPMethyl-2-deoxy-~-galactofuranoside,” W. G. Overend, F. Shafizadeh, and M. Stacey, J . Chem. Soc., (1951) 994-997. “Deoxy-sugars. Part XXI. Synthesis of Some Derivatives of 2-Deoxy-D-galacturonic Acid,” W. G. Overend, F. Shafizadeh, and M. Stacey, J . Chem. Soc., (1951) 1487- 1489.
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“Deoxy-sugars. Part XXII. Comparative Rates of Oxidation and Reduction of D-Galactose and 2Deoxy-D-galactose,” W. G. Overend, F. Shafizadeh, and M. Stacey, J. Chem. SOC., (1951) 2062 - 2064. “Organic Fluorides. Part IX. The Formation and Resolution of a-Hydroxy-a-trifluoromethylpropionic Acid,” R. A. Darrall, F. Smith, M. Stacey, and J. C. Tatlow, J. Chem. SOC.,(1951) 2329-2332. “Deoxypentose Nucleic Acids. Part 11. Evidence for a Labile Polymeric Linkage in Deoxypentose Nucleic Acids,” W. G. Overend, M. Stacey, and M. Webb, J. Chem. SOC.,(1951) 2450-2452. “Detection of Sugars by Paper Chromatography,” R. J. Bayly, E. J. Bourne, and M. Stacey, Nature, 168 (1951) 510. “Properties and Reactions of Mixtures of Trifluoroacetic Anhydride and Oxy-acids,” E. J. Bourne, J. E. B. Randles, J. C. Tatlow, and J. M. Tedder, Nature, 168 (1951) 942-943. “The Synthesis of Uronic Acids,” S. A. Barker, E. J. Bourne, and M. Stacey, Chem. Ind. (London), (195 1) 970.
“The Isolation of Deoxyribonucleic Acid from Virulent and Avirulent Strains of Haemophilus pertussis.” W. G. Overend. M. Stacey, M. Webb, and J. Ungar, J . Gen. Microbiol.,5 (1951) 268-275. “Trifluoroacetic Anhydride, A New Tool in Organic Chemistry,” E. J. Bourne, M. Stacey, and J. C. Tatlow, Abstr. 12th Int. Congr. Pure Appl. Chem. (New York), (1951) 430. “Bacterial Dextrans,” M. Stacey and C. R. Ricketts, Forfschr. Chem. Org. Naturstoffe, Springer-Verlag: Wien, 8 (1951) 28-46. “Degradation of Dextran by Ultrasonic Waves,” M. Stacey, Research, 4 (195 1) 48. “The Q-enzyme of Polytomella coeca.” A. Bebbington, E. J. Bourne, M. Stacey, and 1. A. Wilkinson, J. Chem. SOC.,(1952) 240-245. “Deoxy-sugars. Part XXIII. An Extension of the Investigation of the Dische Reaction,” R. Allerton, W. G. Overend, and M. Stacey, J. Chem. SOC..(1952) 255-257. “Deoxypentose Nucleic Acids. Part HI. Some Effects of Ultrasonic Waves on Deoxypentose Nucleic Acids,” S. G. Laland, W. G. Overend, and M. Stacey, J . Chem. SOC.,(1952) 303-310. “The iso-Propylidene Derivatives of Hexahydric Alcohols. Part 11. iso-Propylidene Derivatives of Sorbitol (D-Glucitol),” E. J. Bourne, G. P. McSweeney, M. Stacey, and L. F. Wiggins, J. Chem. Soc., ( 1952) I408 - I4 14. “Studies of Trifluoroacetic Acid. Part V. Trifluoroacetic Anhydride as a Condensing Agent in Reactions of Nitrous and Nitric Acids,” E. J. Bourne, M. Stacey, J. C. Tatlow, and J. M. Tedder, J . Chem SOC.,(1952) 1695-1696. “2:4-3:5-Diethylidene aldehydo-L-xylose and its Derivatives,” E. J. Bourne, W. M. Corbett, and M. Stacey, J. Chem. SOC.,(1952) 2810-2812. “Deoxy-sugars. Part XXIV. Conversion of D-Ghcal into Furan Derivatives,” F. Shafizadeh and M. Stacey,J. Chem. Soc., (1952) 3608-3610. “Organic Fluorides. Part XIII. The High-temperature Dimerisation of Chlorotrifluoroethylene,” M. W. Buxton, D. W. Ingram, F. Smith, M. Stacey, and J. C. Tatlow, J. Chem. SOC.,(1952) 38303834. “Organic Fluorides. Part XIV. The Synthesis of Some Aromtic Fluoro- and Choro-compounds,” L. V. Johnson, F. Smith, M. Stacey, and J. C. Tatlow, J. Chem. SOC.,(1952) 4710-4713.
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”The Condensation of Long-chain Fatty Acids with Polysaccharides and Proteins,” A. S. Jones, M. A. G. Kaye, and M. Stacey, J. Chem. Soc., (1952) 5016-5020. “Structure of the Polyglucosan from Aspergillus niger Strain 152,” S. A. Barker, E. J. Bourne, and M. Stacey, Chem. Ind. (London), (1952) 756-151. “Synthesis of Some Phosphates of 2-Deoxy-~-ribose,”R. Allerton, W. G. Overend, and M. Stacey, Chem. Ind. (London), (1952) 952-953. “Structure of a Novel Dextran Synthesized by a Betacoccus arabinosaceous,” S . A. Barker, E. J. Bourne, G. T. Bruce, and M. Stacey, Chem. Ind. (London), (1952) 1156. “Detection of Sugars by Paper Chromatography: The Glycosylamines,” R. J. Bayly, E. J. Bourne, and M. Stacey, Nature, 169 (1952) 876. “Organic Fluorides. X. The Formation of Fluoro-oils and Resins by the Polymerisation of Hydrofluorocarbons with Fluorine,” F. Smith, M. Stacey, J. C. Tatlow, and (in part) J. K. Dawson, and B. R. J. Thomas.J.App1. Chem., 2 (1952) 97-105. “Contribution to Biochemical Research Foundation Seminar on the ‘Chemistry of Nucleic Acids’,” M. Stacey, J . Franklin Inst., 253 (1952) 89. “Synthetic Substances of the Polysaccharide Type,” M. Stacey and W. G. Overend, Erir. Pat., (1952) NO 684689, 1-3. “The Nature of Some of the Linkages in Deoxypentose Nucleic Acids,’’ W. G. Overend, A. R. Peacocke, and M. Stacey, J . Sci. Food Agric., 8 (1952) 105- 111. (Paper read at XIIth IUPAC Int. Congr., New York, 1951). “The Chemistry of the 2-Arninosugars (2-Amino-2-deoxysugars),”A. B. Foster and M. Stacey, Adv. Carbohydr. Chem.. 7 (1952) 247-288. “Researches on British Dextran,” M. Stacey, Sugur J . (1952) 18- 19 “Studies of Trifluoroacetic Acid. Part VIII. Diazotisations of Aromatic Amines in Aqueous TriHuoroacetic Acid and Other Perhalogeno-carboxylic Acids,” M. R. Pettit, M. Stacey, and J. C. Tatlow, J. Chem. Soc., (1953) 3081-3084. “Studies of Aspergillus niger. Part I. The Structure of the Polyglucosan Synthesised by Aspergillus niger 152,” S. A. Barker, E. J. Bourne, and M. Stacey, 1.Chem. Soc., (1953) 3084-3090. “Structure and Reactivity of Anhydro-sugars. Part I. Branched-chain Sugars. Part I. Action of DiA. B. Foster, W. G. ethylmagnesium on Methyl 2:3-Anhydr0-4:6-O-benzylidene-cu-o-mannoside,” Overend, M. Stacey, and G. Vaughan,J. Chem. Soc., (1953) 3308-3313.
“The Role of Carbohydrates in Immunochemistry,” M. Stacey, Eiochem. J., 53 (1953) XIII. “The Role of Carbohydrates in Immunochemistry,” M. Stacey, Eiochem. Soc. Symp., No. 10 (1953) 74-81. “lonophoresis of Some Carbohydrate Derivatives,” A. B. Foster and M. Stacey, J . Applied Chem., 3 (1953) 19-21. “The Separation of Deoxypentosenucleic Acids and Pentosenucleic Acids,” S. K. Dutta, A. S. Jones, and M. Stacey, Eiochim. Eiophys. Actu, 10 (1953) 613-622. “Infrared Absorption Spectra of Dextran and other Polyglucosans,” S. A. Barker, E. J. Bourne, M. Stacey, and D. H. Whiffen, Chem. Ind. (London), (1953) 196- 197.
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“The Structure of (+)-Bomesitol,” A. B. Foster and M. Stacey, Chem. Ind. (London),(1953)279. “Correlation of the Rates of Deamination of Glucosaminides with Configuration at the Glycosidic Centre,”A. B. Foster, E. F. Martlew, and M. Stacey, Chem. Ind. (London). (1953)825-826. “The Anticoagulant Activity of Heparin,” A. B. Foster, E. F. Martlew, and M. Stacey, Chem. Ind. (London),(1953)899-900. “The Synthesis of P-linked Glucosaccharides by Aspergillus niger (Strain 152),”S. A. Barker, E. J. Bourne, and M. Stacey. Chem. Ind. (London),(1953)1287. “Recent Advances in Microbiological Methods. Chemistry of Gram Staining and of the Feulgen and Dische Reactions for Nuclear Material,” M. Stacey, Nature, 171 (1953)507.
“The Chemistry of the 2-Desoxysugars,” W. G. Overend and M. Stacey, Adv. Carbohydr. Chem., 8 (1953)45-105. “Biological Properties and Chemical Synthesis of Phosphoric Esters of Carbohydrates,” A. B. Foster, W. G. Overend, and M. Stacey, Die Sraerke, 5 (1953)285-290. “The Significance of Bacterial Polysaccharides,” M. Stacey, Discovery, (1953)27 1-275. “Aspects of Bacterial Synthesis,” M. Stacey, Research, 6 (1953)159- 165. “Bacterial Polysaccharides,” M.Stacey, Endeavour, 12 (1953)38-42. “Infra-red Spectra of Carbohydrates. Part I. Some Derivatives of o-Glucopyranose,” S. A. Barker, E. J. Bourne, M. Stacey, and D. H. Whiffen, J . Chem. Soc., (1954)171 - 176. “Studies upon ol-Trifluoromethylacrylic Acid, a-Trifluoromethyl-propionicAcid, and some Derived Compounds,” M. W. Buxton, M. Stacey, and J. C. Tatlow, J. Chem. Soc., (1954)366-374. “Structural Studies of the Cellulose Synthesised by Acetobacrer acetigenum,” K. S. Barclay, E. J. Bourne, M. Stacey, and M. Webb, J. Chem. Soc., (1954)1501 - 1505. “Immunopolysaccharides. Part I. Preliminary Studies of a Polysaccharide from Azotohacter chroococcum, containing a Uronic Acid,’’ G. J. Lawson and M. Stacey, J . Chem. Soc., (1954)
1925- 193 1. “Studies of Trifluoroacetic Acid. Part XII. Acyl Trifluoroacetates and their Reactions,” E. J. Bourne, M. Stacey, J. C. Tatlow, and R. Worral1,J. Chem. Soc., (1954)2006-2012. “lmmunopolysaccharides. Part 11. Structure of a Betacoccus arahinosaceous Dextran,” S. A. Barker, E. J. Bourne, G. T. Bruce, W. B. Neely, and M. Stacey, J . Chem. Soc., (1954)2395-2399. “Deoxy-sugars. Part XXV. Structure and Reactivity of Anhydro-sugars. Part 11. Derivatives of 3:6Anhydro-o-rnannose, 3:6-Anhydro-2-deoxy-o-galactose,and 3:6-Anhydro-2-deoxy-o-glucose,” A. B. Foster, W. G. Overend, M. Stacey, and G. Vaughan, J . Chem. SOC.,(1954)3367-3377. “Deoxy-sugars. Part XXVII. The Catalytic Oxidation of Some Derivatives of 2-Deoxy-o-hexoses,” W. G. Overend, F. Shafizadeh, M. Stacey, and G. Vaughan,J. Chem. Soc., (1954)3633-3634. “The Synthesis of Certain Trifluoromethylquinoline Derivatives,’’ R. Belcher, M. Stacey, A. Sykes, and J. C. Tat1ow.J. Chem. Soc., (1954)3846-3851. “Studies of Trifluoroacetic Acid Part X. The Mechanisms of Syntheses Effected by Solutions of Oxyacids in Trifluoroacetic Anhydride,” E. J. Boume, J. E. B. Randles, M. Stacey, J. C. Tatlow, and J. M. Tedder, J. Am. Chem. Soc., 76 (1954)3206-3208. “Studies on the Chlorination of the Side Chains of Alkylaromatic Compounds,” P. G. Harvey, F. Smith, M. Stacey, and J. C. Tatlow, J . Appl. Chem.. 4 (1954)3 19-325.
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“Studies on the Nuclear Chlorination of Aromatic Compounds,” P. G. Harvey, F. Smith, M. Stacey, and J. C. Tat1ow.J. Appl. Chem.. 4 (1954) 325-330. “The Reactions of Highly Fluorinated Organic Compounds. 111. A Heptafluoroadipic Acid and its Derivatives,” A. K. Barbour, H. D. Mackenzie, M. Stacey, and J. C. Tatlow, J . Appl. Chem., 4 (1954) 34 1-345. “The Reactions of Highly Fluorinated Organic Compounds. IV. Some Polyfluorocycbhexanes and Certain Derived Compounds,” A. K. Barbour, H. D. Mackenzie, M. Stacey, and J. C. Tatlow, J . Appl. Chem.,4(1954) 347-351. “The Action of Lead Tetraacetate on Sugar mercaptals,” E. J. Bourne, W. M. Corbett, M. Stacey, and R. Stephens, Chem. Ind. (London), (1954) 106- 107. “2:4-Di-U-methyl-~-rhamnose.” K. Butler, P. F. Lloyd, and M. Stacey, Chem. Ind. (London), (1954) 107- 108. “Components of the Specific Polysaccharides of Types IX, XII, and XIV Pneumococcus.” M. Heidelberger, S. A. Barker, and M.Stacey, Science, 120 (1954) 781-782. “The Ultra-violet Absorption of Some Degraded Deoxypentose Nucleic Acids,” W. G. Overend, A. R. Peacocke, and M. Stacey, Trans. Furuday SOC.,50 (1954) 305. “Serological Activity of Deoxypentose Nucleic Acids,” U. Blix, C. N. Iland, and M. Stacey, Brit. J . Exptl. Pathol., 35 ( 1954) 24 1-25 1. “Enzymic Synthesis of Polysaccharides,” M. Stacey, Adv. Enzymol., XV (1954) 301 -318 “Schools of Chemistry in Great Britain and Ireland. XII. The University of Birmingham,” S. R. Carter and M. Stacey, J. R.Inst. Chem., 8 (1954) 405-414. “Immunopolysaccharides. Part 111. The Dimethyl Ethers of L-Rhamnopyranose,” K. Butler, P. F. Lloyd, and M. Stacey,J. Chem. Soc., (1955) 1531-1537. “Immunopolysaccharides. Part IV. Structural Studies on the Type I1 Pneumococcus Specific Polysaccharide,” K. Butler and M. Stacey,J. Chem. Soc., (1955) 1537-1541. “The Reactions of Highly Fluorinated Organic Compounds., Part IX. 1H-Decafluoro-4-trifluoromethylcyclohexane, Nonafluoro-4-trifluoromethylcyclohex-l-ene, and Perfluoro-(3-methyladipic) Acid,”C. B. Barlow, M. Stacey, and J. C. Tat1ow.J. Chem. Soc.. (1955) 1749-1752. “Ionophoresis of Carbohydrates. Part 11. Some Pyranose and Furanose Derivatives of o-Glucose,” A. B. Foster and M. 3acey.J. Chem. Soc., (1955) 1778-1781. “Immunopolysaccharides. Part V. Structure of a Modified Betacoccus urubinosaceous Dextran,” S. A. Barker, E. J. Bourne, A. E. James, W. B. Neely, and M. Stacey, J. Chem. Soc., (1955) 2096-2099. “Deoxy-sugars. Part XXIX. A Further Contribution to the Chemistry of the Glycal Reaction,” A. S. Mathews, W. G. Overend, F. Shafizadeh, and M. Stacey, J . Chem. Soc., (1955) 251 1-2514. “Studies of Aspergillus niger. Part 1V. The Synthesis of P-linked Glucosaccharides,” S. A. Barker, E. J. Bourne, G. C. Hewitt, and M. Stacey, J. Chem. Soc., (1955) 3734-3740. “Observations on the Properties of Cetyltrimethylammonium Salts of some Acidic Polysaccharides,” B. C. Bera, A. B. Foster, and M. Stacey,J. Chem. Soc.. (1955) 3788-3793. “New Methods for the Synthesis of 2-Amino-2-deoxyglucosides Utilizing N - 2 , 4-Dinitrophenyl (DNP) Derivatives.” P. F. Lloyd and M. Stacey, Chem. Ind. (London), (1955) 917.
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“The Structure of a Polysaccharide Synthesized by a Streptococcus Isolated from a ‘Ropy Fermentation,’ The Value of Infrared Spectroscopy in Polysaccharide Studies,” S. A. Barker, F. Pautard, I. R. Siddiqui, and M. Stacey, Chem. Ind. (London), (1955)1450- 1451. “Effect of Streptomycin on Various Enzymes Responsible for Syntheses and Degradation of Higher Saccharides,” S. A. Barker, E. J. Bourne, M. Stacey, and R. B. Ward, Narure, 175 (1955)203-204. “Synthesis of Oligosaccharides by Growing Cultures of Berucuccus Arabinosaceous,” R. W. Bailey, S. A. Barker, E. J. Bourne, andM. Stacey, Nature. 175 (1955)635. “Enzymic Synthesis of a Branched Trisaccharide,” R. W. Bailey, S. A. Barker, E. J. Bourne, and M. Stacey,Nature, 176(1955)1164-1165. “Some Recent Advances in Organic Chemistry,” M. Stacey, J. R. Inst. Chem., 79 (1955)421-423. “The Chemistry of Ribose and Deoxyribose,” W. G. Overend and M. Stacey, Chapter 2 in The Nucleic Acids, Vol I. Chemistry and Biology, Edited by E. Chargaff and J. N. Davidson, Academic Press, (1955)9-80. “Contribution to Ciba Foundation Symposium on Experimental Tuberculoses,” R. J. Bayley, A. S. Jones. and M. Stacey, Ciba Found. Symp. (1955)61. “Biological Synthesis of Carbohydrates. Third Frankland Memorial Lecture,” .I. R . Inst. Chem., 79
(1956)591-592. “Ionophoresis of Carbohydrates. Part 111. Behaviour of Some Amylosaccharides and their Reaction with Borate Ions,” A. B. Foster, P. A. Newton-Heam, and M. Stacey, J. Chem. Soc.. (1956)30-36. “The Nucleotide Sequence in Deoxypentosenucleic Acids. Part 11. The Alkaline Degradation of Calfthymus aldehydo Apurinic Acid Di(carboxymethy1) Dithioacetal,” A. S. Jones, D. s. Letham, and M. Stacey, J. Chem. Sac., (1956)2579-2583. “The Nucleotide Sequence in Deoxypentosenucleic Acids. Part 111. The Nature of the End Groups Produced by Alkaline Hydrolysis of Calf Thymus aldehydo Apurinic Acid Di(carboxymethy1) Dithioacetal,”A. S. Jones, D. S. Letham. and M. Stacey,J. Chem. Soc., (1956)2584-2586. “Amino-sugars and Related Compounds. Part I. The Deamination of D-Glucosamine Hydrochloride,” B. C. Bera, A. B. Foster, and M. Stacey, J . Chem. Soc., (1956)4531 -4535. “Polysaccharides from f.Luteum Zukal,” P. F. Lloyd, M. G. Pon, and M. Stacey, Chem. Ind. (London). (1956)172-173. “Observations on the Acidic Hydrolysis of Some D-Ghcosamine Derivatives,” A. B. Foster, D. Horton, and M. Stacey, Chem. Ind. (London)., (1956)175- 176. “The Action of Gamma-radiation on Dilute Aqueous Solutions of Amylose,” E. J. Bourne, M. Stacey, and G. Vaughan, Chem. Ind. (London), (1956)573-574. “Radiation as a Tool in the Synthesis of Organic Compounds,” E. G. Bourne, M. Stacey, and G. Vaughan, Chem. fnd. (London), (1956)1372- 1376. “Industrial and Medical Uses of Carbohydrates,” (Ivan Levenstein Memorial Lecture), M. Stacey, Chem. fnd. (London), (1956)1398- 1408. “Ionophoresis of Oligosaccharides as N-Benzylglycosylammonium Ions,” S. A. Barker, E. J. Bourne, P. M. Grant, and M. Stacey, Naiure, 177 (1956)1125. “Hexafluorobenzene,” J. A. Godsell, M. Stacey, and J. C. Tatlow, Nature, 178 (1956)199-200. “Enzymic and Chemical Synthesis of the a-1:2-glucosidic Linkage: Enzymic Synthesis,” S. A. Barker, E. J. Bourne, P. M. Grant, and M. Stacey, Nature, 178 (1956)1221 -1223.
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“Clinical Analysis of Tissue Polysaccharides,” M. Stacey and S. A. Barker, J . Clin. Pathol., 9 (1956) 314-315. “Amino-sugars and Related Compounds. Part 11. Observations on the Acidic Hydrolysis of Derivatives of 2-Amino-2-deoxy-~-glucose(D-Glucosamine),” A. B. Foster, D. Horton, and M. Stacey, J . Chem. Soc., (1957) 81-86. “The Separation of Reducing Carbohydrates as their N-Substituted Glycosylammonium Ions,” S. A. Barker, E. J. Bourne, P. M. Grant, and M. Stacey, J . Chem. Soc., (1957) 2067-2071. “Studies of Aspergillus niger. Part VI. The Separation and Structures of Oligosaccharides from Nigeran,” S. A. Barker, E. J. Bourne. D. M. O’Mant, and M. Stacey, J . Chem. Soc., (1957) 2448 - 2454. “The Nucleotide Sequence in Deoxypentosenucleic Acids. Part IV. The Deoxyribonucleic Acid of Mycobacterium phlei,” A. S . Jones, M. Stacey, and B. E. Watson, J . Chem. Soc., (1957) 2454-2459. “Fluorinated Sulphonic Acids. Part I. Perfluoromethane-, -octane- and -decane-sulphonic Acids and Their Simple Derivatives,” J. Burdon, I. Farazmand, M. Stacey, and J. C. Tatlow, J . Chem. Soc. (1957) 2574-2578. “The Effect of Streptomycin on the Enzymic Synthesis and Degradation of Carbohydrates,” S. A. Barker, E. J. Bourne, M. Stacey, and R. B. Ward, 1.Chem. Soc., (1957) 2994-2998. “Immunopolysaccharides. Part VI. The Isolation and Properties of the Dextransucrase of Betacocous arabinosaceous,” R. W. Bailey, S. A. Barker, E. J. Bourne, and M. Stacey, J. Chem. Soc., (1957) 3530-3536. “Immunopolysaccharides. Part VII. The Transglucosylase Action of Betacoccus arabinosaceous Detransucrase,” R. W. Bailey, S. A. Barker, E. J. Bourne. and M. Stacey, J . Chem. Sac.. (1957) 3536-3541. “Studies of Aspergillus niger. Part VII. The Enzymic Synthesis of 3-~-P-D-Ghcopyranosyi-Dxylose,” S. A. Barker, E. J. Bourne, G . C. Hewitt, and M. Stacey, J . Chem. Soc., (1957) 3541-3544. “The Preparation and Properties of Aryl 2-Deoxy-cy-~-glucopyranosides,” F. Shafizadeh and M. Stacey,J. Chem. SOC.,(1957)4612-4615. “Some Impressions of Russian Chemistry and Biochemistry,” M. Stacey, Proc. Chem. Soc., (1957) 12-17. “Isolation of a Homologous Series of Oligosaccharides from Chitin,” S. A. Barker, A. B. Foster,
M. Stacey, and J. M. Webber, Chem. Ind. (London), (1957) 208. “The Separation of Neutral Polysaccharides,” S. A. Barker, M. Stacey, and G. Zweifel, Chem. Ind. (London), (1957) 330. “Significance of Oligosaccharide Intermediates in Dextran Synthesis,” R. W. Bailey, S. A. Barker, E. J. Bourne, M. Stacey, and 0. Theander, Nature, 179 (1957) 310. “Sialic Acid and Its Relation to Chronic Bronchitus:’ T. Anzai, S. A. Barker, and M. Stacey, Clin. Chim. Acta, 2 (1957) 491 -496. “Immunopolysaccharides. Part VIII. Enzymic Synthesis of 6-O-cy-o-Glucopyranosyl-3-0-methylD-glucose by Betacoccus arabinosaceous,” S . A. Barker, E. J. Bourne, P. M. Grant, and M. Stacey, J. Chem. Soc., (1958) 601-604. “The Synthesis of Some Galactaric (Mucic) Acid Derivatives,” K. Butler, D. R. Lawrence, and M. Stacey, J . Chern. Soc., (1958) 740-743.
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“Immunopolysaccharides. Part IX. The Enzymic Synthesis of Trisaccharides containing the a-1:2Glucosidic Linkage,” R. W. Bailey, S. A. Barker, E. J. Bourne, P. M. Grant, and M. Stacey, J. Chem. Soc., (1958) 1895- 1902. “Amino-sugars and Related Compounds. Part IV. Isolation and Properties of Oligosaccharides Obtained by Controlled Fragmentation of Chitin,” S. A. Barker, A. B. Foster, M. Stacey, and J. M. Wehber,J. Chem. Soc., (1958) 2218-2227. “Structure of the Capsular Polysaccharide of Aerobacfer aerogenes (N.C.T.C. 418);’ S. A. Barker, A. B. Foster, I. R. Siddiqui, and M. Stacey, J . Chem. SOC.,(1958) 2358-2367. “Studies of Aspergillus niger, Part X. Polyol and Disaccharide Production from Acetate,” S. A. Barker, A. G6mez-SBnchez. and M. Stacey, J . Chem. Sor., (1958) 2583-2586. “Production of Mannitol by a Lactobacillus Causing Ropiness in Cider,” S. A. Barker, E. J. Bourne, E. Salt, and M. Stacey, J . Chem. Soc., (1958) 2736-2740.
“The Stereoisomers of 2:4-Dimethyl-l:3-dioxalan,” S. A. Barker, E. J. Bourne, R. M. Pinkard, M. Stacey, and D. H. Whiffen,J. Chem. Soc.. (1958) 3232. “Studies of Trifluoroacetic Acid. Part XV. Further Investigations on the Reactions of Acyl Trifluoroacetates with Hydroxy-compounds,” E. J. Bourne, M. Stacey, I. C. Tatlow, and R. Worrall, J. Chem. SOC., (1958) 3268-3282. “Immunopolysaccharides. Part X. The Structure of the Immunologically Specific Polysaccharide of Pneumococeus Type XIV,” S. A. Barker, M. Heidelberger, M. Stacey, and D. J. Tipper, J. Chem. Soc., (1958) 3468-3474. Catalytic Oxidation of Carbohydrates. Some Properties of Postassium a-D-Glucopyranuronate 1(Dipotassium Phosphate),” S. A. Barker, E. J. Bourne, J. G. Fleetwood, and M. Stacey, J. Chem. Soc.. (1958) 4128-4132. “Immunopolysaccharides. Part XI. Structure of an Acefobacfercapsulafum Dextran,” S. A. Barker, (1958) 4414-4416. E. J. Bourne, G. T. Bruce, and M. Stacey, J. Chem. SOC.,
“Some Paper Chromatographic Studies with Aspergillus niger ‘ 152’ Transfructosylase,” S. A. Barker, E. J. Bourne, M. Stacey, and R. B. Ward, Biochem. J., 69 (1958) 60-62. “Fluorocyclohexanes. 111. 1H:4H/2H- and 1H/2H:4H-Nonafluorocyclohexane and Derived Compounds,’’ J. A. Godsell, M. Stacey, and J. C. Tatlow, Tetrahedron, 2 (1958) 193-202. “Aspects of Stereochemistry, 1. Properties and Reactions of Some Diols,” J. S. Brimacombe, A. B. Foster, M. Stacey, and D. H. Whiffen, Tetrahedron, 4 (1958) 351 -360. “Uronic Acid Determination,” S . A . Barker, A. B. Foster, I. R. Siddiqui, and M. Stacey, Tulanra, 1 (1958) 216-218. “Amino-sugars and Related Compounds. V 2-Amino- 1,6-anhydro-2-deoxy-P-n-altropyranoside hydrochloride,” A. B. Foster, M. Stacey, and S. V. Vardheim, Acra Chem. Scand., 12 (1958) 16051610. “The Action of Alkali on Methyl 2:3-Anhydro-a-o-allopyranoside and 1:5-Anhydro-2-deoxy-3-0toluene-p-sulphonyl-o-a,.abino-hexitol,”A. B. Foster, M. Stacey, and S. V. Vardheim, Acra Chem. S c a d . , 12(1958) 1819-1824. “Structure of the 1:3-O-BenzylidenegIyceritols,”J. S. Brimacombe, A. B. Foster, and M. Stacey, Chem. Ind. (London), (1958) 1128-1129. “Some Reactions of the 1:3-O-BenzyIideneglyceritols,”N. Baggett, A. B. Foster, and M. Stacey, Chem. Ind. (London), (1958) 1229.
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“The New Beilstein,” S. K. Carter and M. Stacey, Prac. Chem. SOC.,(1958)79-80. “Preparative-scale Gas Chromatography,” D. E. M. Evans, W. E. Massingham, M. Stacey, and J. C. Tatlow, Nature, 182 (1958)591-592. “Structure of an Acidic Polysaccharide Elaborated by Aerohacrer aerogenes,” S. A. Barker, A. B. Foster, I. R. Siddiqui, M. Stacey, and S. J. Pirt, Nature. 181 (1958)999. “Some Infrared Studies on the Use of Deuterium in the Carbohydrate Group,” M. Stacey, R. H. Moore, S. A. Barker, H. Weigel, E. J. Bourne, and D. H. Whiffen, Proc. 2nd Geneva U.N. Int. Con$ Peaceful Uses of Atomic Energy, 20 (1958)251 -256. “The Phosphorus-containing Compounds of Gram-positive and Gram-negative Organisms in Relation to the Gram Staining Reaction,” A. S. Jones, S. B. H. Rizvi, and M. Stacey, J. Gen. Microhiol..
18 (1958)597-606. “Carbohydrates of Nucleic Acids,” M. Stacey, Proc. IVrh Int. Congr: Biochem., (1958)302-3 14. “Ketose-polyol Interconversions by a Ropy-cider Organism,” S. A. Barker, E. J. Bourne, E. Salt, and M. Stacey,J. Chem. Soc., (1959)593-598. “Aromatic Polyfluoro-compounds. Part 11. Pentafluorophenol,” E. J. Forbes, R. D. Richardson, M. Stacey, and J. C. Tatlow. J . Chem. Soc.. (1959)2019-2021. “Effects of y-Radiation. Part I. Polymer Formation from Sugars, Hydroxy-acids and Amino-acids.” S. A. Barker, P. M. Grant, M. Stacey, and R. B. Ward, J. Chem. Soc., (1959)2648-2654. “Reactions of Some Alkyl Iodides with Periodate,” A. B. Foster, M. Stacey, and R. W. Stephens, J. Chem. Sac., (1959)2681-2687. “Studies of Aspergillus niger. Part X I . Enzymic Synthesis of a Pseudoaldobiuronic Acid,” S. A. Barker, A. Gomez-Shnchez, and M. Stacey. J . Chem. SOC.,(1959)3264-3269. “Amino-sugars and Related Compounds. VI. The Action of Alkali on Some Benzyloxycarbonylamino Derivatives.” A. B. Foster, M. Stacey, and S. V. Vardheim, Acta Chem. Scund., 13 (1959)
281-288. “Hydrolysis of the Cyclic Sulphates of Cyclohexane-cis- and trans-l,2-Dioland Related Compounds,” J. S. Brimacombe, A. B. Foster, and M. Stacey, Chem. Ind. (London),(1959)262-263. “The Formation of Carbohydrates by Aldol Condensations,” J. A. Gascoigne, W. G. Overend, and M. Stacey, Chem. Ind. (London), (1959)402-403. “Effects of Gamma-radiation on Some Carbohydrates, Hydroxy-acids, and Amino-acids in Aqueous Solutions,” S. A. Barker, P. M. Grant, M. Stacey, and R. B. Ward, Nature, 183 (1959)376-377. “A New General Route to Aromatic Fluorocarbons,” B. Gething, C. R. Patrick, M. Stacey, and J. C. Tatlow, Nature, 183 (1959)588-589. “N-Methylation of Methyl 2-Acetamido-2-deoxy-a-~-gluco-pyranoside,” S. A. Barker, M. Stacey, and D. I. Tipper, Nature, 184 (1959)1718. “Observations on Some Carbohydrate Benzylidene Derivatives:’ B. Dobinson, A. B. Foster, and M. Stacey, Tetruhedron Lett., (1959)1. “Neuraminic Acid and Its Relation to Chronic Bronchitis, 111. Carbohydrate Constituents of Sputum,” M. Z. Atassi, S. A. Barker, and M. Stacey, Clin. Chim. Actu, 4 (1959)823-827. “Polysaccharide Analysis of Liver Biopsy Specimens Obtained at Laparotomy,” D. J. Tipper, M. Stacey, and S. A. Barker, Clin.Chim. A m , 4 (1959)861 -866.
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“The Fascinating Fluorocarbons,” M. Stacey, TNew Sci., 5 (1959) 74-76 “Aspects of Stereochemistry. Pan 111. Acidic and Basic Hydrolysis of Some Diol Cyclic Sulphates and Related Compounds,” J. S. Brimacombe, A. B. Foster, E. B. Hancock, W. G. Overend, and M. Stacey,J. Chem. Soc., (1960) 201-21 I . “Aromatic Perfluoro-compounds. Part IV. The Reaction of Aromatic Polyfluoro-compounds with Nitrogen-containing Bases,” G. M. Brooke, J. Burdon, M. Stacey, and J. C. Tatlow, J. Chem. Soc., (1960) 1768- I77 1. “Aspects of Stereochemistry, Part IV. Configuration and Some Reactions of 1:3-O-Benzylideneglycerols (5-Hydroxy-2-phenyl-l:3-dioxans),”N. Baggett, I. S. Brimacombe, A. B. Foster, M. Stacey, and D. H. Whiffen, J . Chem. SoL... (1960) 2574-2581. “Amino-sugars and Related Compounds. Part VII. 2-Amin0-2-deoxy-l,3,4,5-tetra-O-methyI-oglucitol, 2-Amino-2-deoxy-~-threitoland Certain Derivatives Thereof,” A. B. Foster, D. Horton, N. Salim, M. Stacey, and J. M. Webber, J . Chem. Soc.. (1960) 2587-2596.
“Trifluoroisopropylidene Derivatives of Mannitol,” E. J. Bourne, A. J. Huggard. M. Stacey, and J. C. Tatlow, J . Chem. Sac., (1960) 2716-2720. “Some Alkyl p-Phenylazobenzoates and Ferrocenecarboxylates,” N. Baggett, A. B. Foster, A. H. Haines, and M. Stacey, J . Chem. Soc., (1960) 3528-3531. “Aromatic Polyfluoro-compounds. Part VI. Penta- and 2,3,5,6-Tetrafluorothiophenol,”P. Robson, M. Stacey, R. Stephens, and J. C. Tatlow, J . Chem. Soc., (1960) 4754-4760. “Reactions of 2-(2‘ ,4‘-Dinitrophenyl)-amino-2-deoxy-o-glucose, (DNP-o-glucosamine), and derivatives,” P. F. Lloyd and M. Stacey, Tetrahedron, 9 (1960) 116- 124. “Pentafluoropyridine,” J. Burdon, J. D. Gilman, C. R. Patrick, M. Stacey, and J. C. Tatlow, Nature, 186(1960) 231-232. “Infra-red Spectra of Deuterium-labelled Carbohydrates,” S. A. Barker, R. H. Moore, M. Stacey, and D. H. Whiffen, Nature, 186 (1960) 307-308. “The Exhaustive Fluorination of Organic Compounds by High Valency Metal Fluorides,” M. Stacey and J. C. Tatlow, Adv. Fluorine Chem., 1 (1960) 166- 198. “Progress in Organic Fluorine Chemistry,” M. Stacey, J . Royal Inst. Chem., 84 (1960) I1 - 14. “New Data about the Structure of Antigenic Polysaccharides of Pneumococcus,” S . A. Barker, M. Stacey, and J. M. Williams, Bull. Soc. Chim. B i d . , 42 (1960) 161 1 - 1618. “Uses of Radio-isotopes in the Physical Sciences and Chemistry,” S. A. Barker, M. C. Keith, M. Stacey, and D. 8. E. Stroud, Paper RICC16 Copenhagen Meeting, September 1960.
Polysaccharides of Micro-organisms, M. Stacey and S. A. Barker, Ciarendon Press: Oxford, (1960) IX + 228. Foreword in Laboratory Management and Techniques, by J. R. Edwards, Butterworths: London ( 1960). “Sintesis Enzymatica de Oligosacaridos del Tip0 ‘Acido Pseudoaldobiuronico’,” S. A. Barker, A. Ghez-Sinchez, and M. Stacey, Rev. Esp. Fisiol., 16 suppl 1(1960) 261 -268. “Amino-sugars and Related Compounds. Part VIII. Some Properties of 2-Deoxy-2-sulphoaminoD-glucose, Heparin, and Related Substances,” A. B. Foster, E. F. Martlew, M. Stacey, P. J. M. Taylor, and J. M. Webber, J . Chem. SOL...(1961) 1204- 1208.
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“Enzymic Synthesis of a Glucoxylan,” S. A. Barker, M. Stacey, and D. B. E. Stroud, J. Chem. Sac., (1961) 3995-3998. “Effects of y-Radiation. Part V. Irradiation of Cyclohexene and Cyclohexanol,” A. J. Bailey, S. A. Barker, R. H. Moore, and M. Stacey,J. Chem. Soc., (1961) 4086-4089. “Ionophoresis of Carbohydrates. Part VII. 2,5-Di-O-methyl-~-rhamnose:Its Ionophoresis and ConA. B. Foster, J. Lehmann, and M. Stacey, J . Chem. version into 6-Deoxy-2:5-di-O-methyl-~-altrose,” Sou., (1961) 4649-4653. “Carbohydrate Components of Antibiotics. Part I. Degradation of Desosamine by Alkali: its Absolute Configuration at Position 5,” C. H. Bolton, A. B. Foster, M. Stacey, and J. M. Webber, J . Chem. Soc., (1961) 4831-4836. “Silyl ethers of Tetrahydro-2-hydroxymethylpyran,”S. A. Barker, J. S. Brimacombe, M. R. Hamden, and M. Stacey, J . Chem. Soc., (1961) 5256-5258. “The Identity of the Uronic Acid in Heparin,” A. B. Foster, A. H. Olavesen, M. Stacey, and J. M. Webber, Chem. Ind. (London), (1961) 143. “Enzymic Synthesis of 3-O-~-D-GlUCOpyranOSyl-D-XylOSe,” S. A. Barker, M. Stacey, and D. B. E. Stroud, Narure, 189 (1961) 138. “Two New Amino-sugars from an Antigenic Polysaccharide of Pneumococcus,” S. A. Barker, J . S. Brimacombe, M. J. How, M. Stacey, and 3. M. Williams, Nature, 189 (1961) 303-304. “Monosaccharide Sequence in Pneumococcus Type XIV Polysaccharide,” S. A. Barker, M. C. Keith, and M. Stacey, Narwre, 189 (1961) 746-747. “Mannosyl D-(;lucosamine Hydrochloride Isomers,” S. A. Barker, K. Murray, M. Stacey, and D. B. E. Stroud, Narure, 191 (1961) 142-144. “Polymer Production from Carbohydrates,” R. J. Bailey, S. A. Barker, and M. Stacey, Radiar Res., 15 (1961) 538-545. “Intramolecular Hydrogen Bonding in Some Acyclic Alcohols,” A. B. Foster, A. H. Haines, and M. Stacey, Tetrahedron, 16 (1961) 177-184. “Periodate Oxidation of Heparin and Related Compounds.” A. B. Foster, R. Harrison, T. D. Inch, M. Stacey, and J. M. Webber, Biochem. J., 80 (1961) 12P-13P (Proceedings of the Biochemical Society 405th Meeting at Univ. of Birmingham, April 28-29, 1961). “Reaction of Heparin with HI4CN,”A. B. Foster, M. Stacey, P. J. M. Taylor, J. M. Webber, and M. L. Wolfrom, Biochem. J . . 80 (1961) 13P- 14P (Proceedings of the Biochemical Society 405th Meeting at Univ. of Birmingham, April 28-29, 1961). “Carbohydrate Components of Antibiotics. Part 11. Alkaline Degradation of Mycaminose and Synand Derivatives Therefrom,” A. B. Foster, thesis of 3,6-Dideoxy-3-dimethylamino-~-altrose J. Lehmann, and M. Stacey, J . Chem. Soc., (1962) 1396- 1401. “Carbohydrate Components of Antibiotics. Part 111. Synthesis of 3.6-Dideoxy-3-dimethylamino-pD-glUcOSe Hydrochloride Monohydrate: the Absolute Configuration of Mycaminose,” A. B. Foster, T. D. Inch, J. Lehmann, M. Stacey, and J. M. Webber,J. Chem. Soc.. (1962) 2116-2118. “Structure of Pneumococcus Capsular Polysaccharides,” S. A. Barker and M. Stacey, Biochem. J.. 82 (1962) 37P. “Polymerisation of Glucose Induced by y-Radiation,” S. A. Barker, I. R. L. Lloyd, and M. Stacey, Radiation Res. 16 (1962) 224-231.
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“Structure of a Radiation-induced Polymer from Glucose,” S. A. Barker, I. R. L. Lloyd, and M. Stacey, Radiation Res., 17 (1962)619-624. “The Vapour Phase Fluorination of Trichloroethylene with Cobalt Trifluoride and with Manganese Trifluoride,” G. Fuller, M. Stacey, J. C. Tatlow, and C. R. Thomas, Tetrahedron, 18 (1962)123- 133.
“Identification of Mycaminose as 3,6-Dideoxy-3-dimethylamino-~-glucose,” A. B. Foster, T. D. Inch, J. Lehmann, M. Stacey, and J. M. Webher, Chem. lnd. (London), (1962)142. “Octafluorostyrene,” B. R. Letchford, C. R. Patrick, M. Stacey, and J. C. Tatlow, Chem. I n d . (London), (1962)1472- 1473. “A review of The Chemistry of Organic Fluorine Compounds (by M. Hudlicky, Pergamon Press Ltd, 1961):’ M. Stacey, Chem. Ind. (London), (1962)1713. “The Configuration of Desosamine,” C. H. Bolton, A. B. Foster, M. Stacey, and J. M. Webber, Chem. Ind. (London),(1962)1945- 1946.
“Chemistry of a Case of Juvenile Amaurotic Idiocy,” S. A. Barker, S. H. I. Bayyuk, and M. Stacey, Nature, 196 (1962)64-65. “Neuraminic Acid and its Relation to Chronic Bronchitis. IV. Isolation of Homogeneous Mucoproteins,” M. Z. Atassi, S. A. Barker, and M. Stacey, Clin. Chim. Acta, 7 (1962)588-591. “Neuraminic Acid and its Relation to Chronic Bronchitis. V. Glass Column Electrophoresis of Sputum,” M. Z. Atassi, S. A. Barker, and M. Stacey, Clin. Chim. Acta, 7 (1962)706-709. Carbohydrates of Living Tissues, M. Stacey and S. A. Barker, Van Nostrand Co. Ltd., London, (1962)p. XVII + 215. “2-Amino-2-deoxy-a-~-glucose(a-D-Glucosamine) from Crustacean Shell,” M. Stacey and J. M. Webber, Methods Carhohydr. Chem., 1 (1962)228-230.
“Nigerose (3-O-cY-D-glUCOpyranOSyl-D-glUCOSe). Partial Hydrolysis of Nigeran,” M. Stacey and J. M. Webber, Methods Carhohydr. Chem., 1 (1962)339-341. “Effects of y-Radiation. Part VII. Irradiation of 2,3-Dihydro-4H-pyran and Related Compounds,” A. J. Bailey, S. A. Barker, and M. Stacey,J. Chem. Soc., (1963)1659- 1662. “Effects of ?-Radiation. Part VIII. Irradiation of D-GIucal in Aqueous Solution,” A. J. Bailey, S. A. Barker, and M. Stacey, J. Chem. Soc., (1963)1663- 1666. “Amino-sugars and Related Compounds. Part IX. Periodate Oxidation of Heparin and Some Related Substances,” A. B. Foster, R. Harrison, T. D. Inch, M. Stacey, and J. M. Webber, J . Chem. Soc., (1963)2219-2287. “Polycyclic Fluoroaromatic Compounds. 111. Octafluoro-acenaphthylene, and Decafluoro-indane, -acenaphthene, -anthracene, and -pyrene,” D. Harrison, M. Stacey, R. Stephens, and J. C. Tatlow, Tetrahedron, 19 (1963)1893-1901. “Carbohydrate Chemistry,” M. Stacey, Chem. Ind. (London).(1963)669. “Sequential Enzyme Induction: A New Approach to the Structure of Con~plexMucoproteins,” S. A. Barker, G. I. Pardoe, M. Stacey, and J. W. Hopton. Nature. 197 (1963)231 -233. “Capsular Polysaccharide of Klebsiella pneumoniae Type A (Strain 1265):’ S. A. Barker, J. S. Brimacombe, J. L. Eriksen, and M. Stacey, Nature, 197 (1963)899-900. “Configurational Correlation of Desosamine and Chalcose,” A. B. Foster, M. Stacey, J. M. Webber, and J. H. Westwood, Proc. Chem. Soc.. (1963)279-280.
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“A Chemical Investigation of Two Cases of Glycogen Storage Disease,” S. A. Barker, M. Stacey, and M. A. L. Al-Farisi, Clin. Chim. Actu, 8 (1963)31 1-314. “Fingerprinting the Hyaluronic Acid Component of Normal and Pathological Synovial Fluids,” S. A. Barker, S. H. I. Bayyuk, J. S. Brimacombe, C. F. Hawkins, and M. Stacey, Clin. Chim. Actu, 8 (1963) 902-909. “New Keys to Nature’s Codes,” S. A. Barker and M. Stacey, Discovery. (1963)36-40. “The Carbohydrates of Milk and Colostrum,” S. A. Barker and M. Stacey, Dairy Sci. Absrr., 25 (1963)445-450. “The Fine Structure of the Carbohydrate Moiety of Urinary Orosomucoid,” S. A. Barker, G . I. Pardoe, M. Stacey, and J. W. Hopton, in H. Peeters (Ed.) Protides ofthe Biological Fluids, Elsevier Publishing Co: Amsterdam, 11 (1963)284-287.
“Synthesis of Mycinose (6-Deoxy-2,3-di-O-methyl-~-allose),” J. S. Brimacombe, M. Stacey, and L. C. N. Tucker,J. Chem. Sor., (1964) 5391 -5392. “Synthesis of Chromose A:’ J. S. Brimacombe, D. Portsmouth, and M. Stacey, J. Chem. Soc., (1964) 5614-5617. “Synthesis of Chromose A (2,6-Dideoxy-4-0-methyl-o-galactose).” J. S. Brimacornbe, D. Portsmouth, and M. Stacey, Chem. Ind. (Londonj, (1964)1758. “Synthesis of Mycinose,” J. S. Brimacombe, M. Stacey, and L. C. N. Tucker, Proc. Chem. Soc., (1964)83. “Degradation of Type XIV Pneumococcus Polysaccharide by Induced Enzymes,” S. A. Barker, G . I. Pardoe, M. Stacey, and J. W. Hopton, Nature, 204 (1964)938-939. “The Structure of the Hyaluronic Acid Component of Synovial Fluid in Rheumatoid Arthritis,’’ S. A. Barker, S. H. I. Bayyuk, J. S. Brimacornbe, C. F. Hawkins, and M. Stacey, Clin. Chim. Actu, 9 (1964) 339-343.
“The Pneumococcal Polysaccharides,” M. J. How, J. S. Brimacornbe, and M. Stacey. Adv. Carbohydr. Chem., 19 (1964)303-358. Foreword in Mucopolysaccharides, by 5. S . Brimacornbe and J. M. Webber, Elsevier Publishing Co: Amsterdam, (1964). “Aromatic Polyfluoro-compounds. Part XXI. Reactions of the Pentatluorodiazonium Ion,” G. M. Brooke, E. J. Forbes, R. D. Richardson, M. Stacey, and J. C. Tatlow, J . Chem. Soc., (1965) 2088-2094. “Carbohydrate Components of Antibiotics. Part IV. Configurational Correlation of Desosamine and Chalcose,” A. B. Foster, M. Stacey, J. M. Webber, and J. H. Westwood, J . Chem. Soc.. (1965) 23 18-2323. “Arrangement of L-Rhamnose Units in Diplococcus pneumoniue Type I1 Polysaccharide,” S. A. Barker, P. J. Somers, M. Stacey, and J. W. Hopton, Curbohydr. Res., 1 (1965)106- 115. “A New Synthesis of L-Fucosamine (2-Amino-2,6-dideoxy-~-galactose),”J. S. Brimacombe, J. G . H. Bryan, and M. Stacey, Curbohydr. Res., 1 (1965)258-260. “Fingerprinting the Hyaluronic Acid-Protein Complex of Human Vitreous Humour,” S. A. Barker, S. I. Crews, J. B. Marsters, and M. Stacey, Clin.Chim. Actu, 1 1 (1965)139-145. “Isolation and Preliminary Characterisation of Soil Polysaccharides,” S. A. Barker, P. Finch, M. H. B. Hayes, R. G . Simmonds, and M. Stacey, Nature, 205 (1965)68-69.
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“Inhibition of Hyaluronic Acid Degradation by Dimethyl Sulphoxide,” S. A. Barker, S. J. Crews, J. B. Musters, and M. Stacey, Nature, 207 (1965) 1388-1389. “Alkylation of Carbohydrates using Sodium Hydride,” J. S. Brimacornbe, B. D. Jones, M. Stacey, and J. J. Willard, Carbohydr. Res.. 2 (1966) 167-169. “Structural Studies of the Capsular Polysaccharide of Pneumococcus Type V,” S . A. Barker, S. M. Bick, J. S. Brimacornbe, M. J. How, and M. Stacey, Carbohydr. Res., 2 (1966) 224-233. “Glycosylureas. 111. The Synthesis of D-Mannosyl- and D-Galactosylureas,” E. A. M. Badawi, A. S. Jones, and M. Stacey, Tetrahedron, Suppl. 7 (1966) 281-285. “Aryl 2-Acetamido-2-deoxy-~-~-glucopyranosides-Potential Anti-inflammatory agents,” S. A. Barker, R. G. Plevey, R. G. Simmonds, and M. Stacey, Tetrahedron, Suppl. 8 (Part 11) (1966) 61 1-619. “The Troubles of a Dean or Some Thoughts on the Present and Future Training of Scientists and Engineers,” M. Stacey, Chem. Ind. (London), (1966) 279-283. “Obituary of Dr. Sidney Raymond Carter (1889-1966):’ 697 - 698.
M. Stacey, Chem. Ind. (London), (1966)
“John Albert Newton Friend 1881- 1966 An Obituary,” M. Stacey and W. H. J. Vernon, Chem. Br., 2 (1966) 501-502. “Studies on Soil Polysaccharides and on Their Interaction with Clay Preparations. Soil Chemistry and Fertility,’’ P. Finch, M. H. B. Hayes, and M. Stacey, (1966) Trans. Cumm. II&IV Int. SOC.Soil Sci., Aberdeen, G. V. Jacks, Ed. (1967) 19-32. “Sequence Studies on Diplococcus pneumoniae Type II Polysaccharide,” S. A. Barker, P. J. Somers, and M. Stacey, Carbohydr. Res., 3 (1967) 261 -270. “The Oxidation of Some Carbohydrate Derivatives using Acetic Anhydride - Methyl Sulphoxide and Mixtures and the Pfitzner-Moffat Reagent. Facile Synthesis of 3-Acetamido-3-deoxy-D-glucose 3-hino-3-deoxy-D-xylose,” J. S. Brimacornbe, J. G. H. Bryan, A. Husain, M. Stacey, and M. S . Tolley, Carhohydr.Res., 3 (1967) 318-324. “Linkage Analysis of Carbohydrates by Using Saccharinic Acid Formation,” S . A. Barker, A. R. Law, P. J. Sorners, and M. Stacey, Carhohydr. Res., 3 (1967) 435-444. “Studies on Soil Polysaccharides, I.,” S. A. Barker, M. H. B. Hayes, R. G. Sirnmonds, and M. Stacey, Carbohydr: R w . , 5 (1967) 13-24. “The Capsular Polysaccharide of Type I Pneumococcus. I Purification and Clinical Modification,” R. C. E. Guy, M. J. How, M. Stacey, and M. Heidelberger, J . Biol. Chem., 242 (1967) 5106-511 1. “Polarographic Analysis of s-Triazine Herbicides,” M. H. B. Hayes, M. Stacey, and J. M. Thompson, Chem. Ind. (London), (1967) 1222- 1223. “Nucleophilic Displacement Reactions in Carbohydrates. Part 111. Displacements with 1.25.6Di-O-isopropylidene-3-O-toluene-p-sulphonyl-~-~-gulofuranose,” J. S. Brimacornbe, (Miss) P. A. Gent, and M. Stacey, J . Chem. Soc. C , (1968) 567-569. “A Synthesis of 5-Acetamido-5-deoxy-~-lyxopyranose,” J. S. Brimacornbe, F. Hunedy, and M. Stacey, J . Chem. Soc. C, (1968) 1811-1813. “A New Method for Quantitative Microscale Determination of the Sulphate Content of Carbohydrates,” S. A. Barker, J. F. Kennedy, P. J. Somers, and M. Stacey, Carbohydr. Res., 7 (1968) 361-368.
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J. S. Brimacombe, “A Synthesis of Derivatives of L-Perosamine (4-Amino-4,6-dideoxy-~-mannose),” 0. A. Ching, and M. Stacey, Carbohydr. Res., 8 (1968) 498-499. “Syntheses of 6-Deoxy-2- and 3-0-methyl-D-allose and Some 6-Deoxyhexopyranoside Phenylboronates,” J. S. Brimacornbe, A. Husain, F, Hunedy, and M. Stacey, Adv. Chem. Ser., No 74 (“Deoxy-sugars”) (1968) 56-69. “Studies on the Polysaccharide Constituents of an Acid Extract of a Fenland Muck Soil,” P. Finch, M. H. B. Hayes, and M. Stacey, Trans. 9th Int. Congr. SoilSci., 3 (1968) 193-201. “A New Synthesis of Mycinose (6-Deoxy-2,3-di-O-methyl-~-aIlose),” J. S . Brimacombe, 0. A. Ching, and M. Stacey,J. Chem. Soc. C, (1969) 197-198. “Nucleophilic Displacement Reactions in Carbohydrates. Part XI. Reaction of Methyl 6-Deoxy-2.3O-isopropylidene-4-O-methyl-sulphonyl-u-~-talopyranoside with Sodium Azide: A Synthesis of Derivatives,” J. S. Brimacombe, 0. A. Ching, and L-Perosamine (4-Amino-4,6-dideoxy-~-mannose) M. Stacey, J . Chem. SOC.C, (1969) 1270- 1274. “Some Structural Studies of Brea Gum. (An Exudate from Cercridium australe (Johnst.),” A. S. Cerezo, M. Stacey, and J. M. Webber, Carbohydr. Res., 9 (1969) 505-517. “Oxidative Alkaline Degradation of Cellobiose,” R. M. Rowell, P. J. Somers, S. A. Barker, and
M. Stacey, Carbohydr. Res., 11 (1969) 17-25. “The Automated Spectrofluorimetric Determination of Formaldehyde in the Periodate Oxidation of Carbohydrates and Amino-acids,” H. Cho Tun, J. F. Kennedy, M. Stacey, and R. R. Woodbury, Carbohydr. Res., 11 (1969) 225-231. “An Improved Synthesis of N-Acetylneurarninic Acid,” M. J. How, M. D. A. Halford, M. Stacey, and (in part) E. Vickers, Carbohydr. Rex, 11 (1969) 313-320. “Technique Aspects of Carbohydrates,” M. Stacey and P. J. Somers, Laborarory Practice, 18 (1969) 1 172- 1180. “On Collecting Drug Jars,” M. Stacey, Chem. Br., 5 (1969) 398-401. “Studies on the Humification of Plant Tissue,’’ M. H. B. Hayes, M. Stacey, and J. Standley, Proc. 9th Int. Congr. Soil Sci., 3 (1969) 247-256, “Comparative Studies of Lorenzini Jelly from Two Species of Elasmobranch. Part 11. Structural Studies of Glycopeptides,” M. J. How, J. V. S. Jones, and M. Stacey, Carbohydr. Res., 12 (1970) 171-181. “Nucleophilic Displacement Reactions in Carbohydrates. Part XIII. A Synthesis of Benzyl 5,6-Acetylepimino-5,6-dideoxy-2,3-O-isopropylidene-~-~-gulofuranoside,” J. S. Brimacombe, F. Hunedy, and M. Stacey, Carbohydr. Res., 13 (1970) 447-450. “Modem Methodology of Structural Polysaccharide Chemistry,” M. Stacey, Chem. Br., 6 (1970) 113- 118. “Techniques for Fractionating Soil Polysaccharides,” M. H. B. Hayes, M. Stacey, and R. S. Swift, Trans. 10th Int. Congr. SoilSci., 12 (1970) 75-81. “A Synthesis of 3-Amino-3-deoxy-~-lyxose,”J. S. Brimacombe, A. M. Mofti, and M. Stacey, Carbohydr. Res., 16 (1971) 303-308. “P-D-Glucosidase Chemically Bound to Microcrystalline Cellulose,” S. A. Barker, S. H. Doss, C. J. Gray, J. F. Kennedy, M. Stacey, and T. H. Yeo, Carbohydr. Res., 20 (1971) 1-7. “The Future for Chemistry,” R. Nyholm, M. Stacey, and J. W. Linnett, Nature, 234 (1971) 517-519.
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PAUL FINCH AND W. GEORGE OVEREND
“Studies on the Fractionation of Humification Products of Ryegrass on Sand Columns,” M. H. B. Hayes, M. Stacey, and J. Standley, Geoderma, 7 (1972) 105- Lll. “Studies of Bitumen. Part 1. Characterisation of Bitumen by Use of Physical Methods,” M. H. B. Hayes, M. Stacey, and J. Standley, Fuel, 51 (1972) 27-31. “Studies on Bitumen. Part 2. Changes in Bitumen During Weathering,” M. H. B. Hayes, M. Stacey, and J. Standley, Fuel, 5 1 (1972) 32-37. “Studies on Bitumen. Part 3. Experiments on the Biodegradation of Bitumen by Soil Microorganisms,” M. H. B. Hayes, M. Stacey, J. Standley, and (in part) A. E. Entwistle. Fuel, 51 (1972) 146- 149. “Degradation of Humic Acid in a Sodium Sulphide Solution,” M. H. B. Hayes, M. Stacey, and R. S. Swift, Fuel, 51 (1972) 211-213. “Interactions Between Organophosphorus Compounds and Soil Materials I. Adsorption of Ethylmethylphosphonofluoridate by Clay and Organic Matter Preparations and by Soils,” M. H. B. Hayes, P.R. Lundie and M. Stacey, Pestic. Sci., 3 (1972) 619-629. “Industrial Uses of Carbohydrates - Present and Future,” (S. C. I. Jubilee Memorial Lecture), M. Stacey, Chem. lnd. (London). (1973) 222-226. “The Consequences of Some Projects Initiated by Sir Norman Haworth,” (Haworth Memorial Lecture), M. Stacey, Chem. SOC.Rev.,2 (1973) 145- 161. “Spectroscopic Studies on the Mechanisms of Adsorption of Paraquat by Hurnic Acid and Model Compounds,” I. G. Bums, M. H. B. Hayes, and M. Stacey, Pestic. Sci., 4 (1973) 201-209. “Studies of the Adsorption of Paraquat on Soluble Hurnic Fractions by Gel Filtration and Ultrafiltration Techniques,” I. G. Bums, M. H. B. Hayes, and M. Stacey, Pestic. Sci., 4 (1973) 629-641. “Some Physico-chemical Interactions of Paraquat with Soil Organic Materials and Model Compounds. I. Effects of Temperature, Time and Absorbate Degradation on Paraquat Adsorption,” I. G. Bums, M. H. B. Hayes, and M. Stacey, Weed Res., 13 (1973) 67-78. “Some Physico-chemical Interactions of Paraquat with Soil Organic Materials and Model Compounds. 11. Adsorption and Desorption Equilibria in Aqueous Solutions,” I. G. Bums, M. H. B. Hayes, and M. Stacey, Weed Res., 13 (1973) 79-90. “A Microcalorimetric Investigation of the Interactions Between Clay Minerals and Bipyridylium Salts,” M. H. B. Hayes, M. E. Pick, M. Stacey, and B. A. Toms, Proc. 1972 Int. Clay Conf., (1973) 675-682.
“Recent Advances in the Chemistry of the Acidic Mucopolysaccharides, a Short Review,” J. F. Kennedy and M. Stacey, Egypt J . Chem.. Special Issue “Tourky” (1973) 223-233. “Penodate Oxidation, Acid Hydrolysis, and Structure-Activity Relationships of Human Pituitary, Follicle-Stimulating Hormone, and Human Chorionic Gonadotrophin,” J. F. Kennedy, M. F. Chaplin, and M. Stacey, Carhohydr. Res, 36 (1974) 369-371. “Reactions of Sodium Sulphide. I. With Compounds Containing Hydroxyl Groups,” J. Burden, .I. D. Craggs, M. H. B. Hayes, and M. Stacey, Tetrahedron, 30 (1974) 2729-2733. “Edward John Boume. 1922-1974. Pro Summa Fide Summus Amor,” M. Stacey and H. Weigel., Carhohydr. Res., 49 (1976) 1-2. “G. L. C. of the 0-Trimethylsilyl derivatives of Hexuronic Acids,” J. F. Kennedy, S. M. Robertson, and M. Stacey, Carbohydr. Res., 49 (1976) 243-258.
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“Carbohydrates to Fill the Chemical Gap,’’ M. Stacey, Spectrum, 146 (1976) 11 - 13. “Straw as Potential Raw Material for Chemicals,” M. Stacey, Agric. Progr., 5 1 (1976) 69-75. “Edmund Langley Hirst (1898- 1975):’ M. Stacey and E. Percival, Biographical Memoirs of Fellows of the Royal Society, 22 (1976) 137- 168. “Structural Identification of Isomeric 0-Trimethylsilyl Derivatives of Some Hexuronic Acids,” J. F. Kennedy, S. M. Robertson, and M. Stacey, Carhohydr. Res., 57 (1977) 205-214. “The Fluorocarbons-Vast
Field for Research,” M. Stacey, Specrrum, 150 (1977) 14- 15.
“Los Fluorocarburos,” M. Stacey, lberica, (1978) 394-396 Foreword in The Chemistry of Soil Constituents, Ed. D. J. Greenland and M. H. B. Hayes, John Wiley and Sons, (1978). “John Kenyon Netherton Jones 1912- 1977,” M. Stacey, Biographical Memoirs of Fellows of the Royal Society, 25 (1979) 365-389. Foreword in Organic Fluorine Compounds and Their Industrial Applications, Ed. R. E. Banks, Ellis Honvood (1979). “Foreword in ‘The Chemistry of Soil Processes’,’’ Ed. D. J. Greenland and M. H. B. Hayes, John Wiley (1981).
“John Kenyon Netherton Jones 1912-1977,” W. A. Szarek, M. Stacey, and G. W. Hay, Adv. Carhohydr. Chem.,41 (1983) 1-26. “Relationships between the Early American School of Carbohydrate Chemistry and the British School,” M. Stacey, Ahstr. Pap. Am. Chem. SOC.Meet., 190 (1985) 23. “Hirst, Sir Edmund Langley (1898- 1975);’ M. Stacey, The Dictionary of National Biography 1971 -80, Oxford University Press, (1986) 41 I .
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INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY and
INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY
JOINT COMMISSION ON BIOCHEMICAL NOMENCLATURE*
NOMENCLATURE OF CARBOHYDRATES (Recommendations 1996) Prepared for publication by
ALAN D. McNAUGHT The Royal Society of Chemistry, Thomas Graham House, Science Park,Milton Road, Cambridge CB4 4WF, UK *Members of the Commission (JCBN) at various times during the work on this document (1983-1996) were as follows: Chairmen: H.B.F. Dixon (UK), J.F.G. Vliegenthart (Netherlands), A. Cornish-Bowden (France); Secretaries: A. Cornish-Bowden (France), M.A. Chester (Sweden), A.J. Barrett (UK), J.C. Rigg (Netherlands); Members: J.R. Bull (RSA), R. Cammack (UK), D.Coucouvanis (USA), D. Horton (USA), M.A.C. Kaplan (Brazil), P. Karlson (Germany), C. Likbecq (Belgium), K.L. Loening (USA), G.P. Moss (UK), 1. Reedijk (Netherlands), K.F. Tipton (Ireland), S. Velick (USA), P. Venetianer (Hungary). Additional contributors to the formulation of these recommendations: Expert Panel: D. Horton (USA) (Convener),0.Achmatowicz (Poland), L. Anderson (USA), S.J. Angyal (Australia), R. Gigg (UK), B. Lindberg (Sweden), D.J. Manners (UK), H. Paulsen (Germany), R. Schauer (Germany). Nomenclature Committee of IUBMB (NC-IUBMB)(those additional to JCBN): A. Bairoch (Switzerland), H. Berman (USA), H. Bielka (Germany). C.R. Cantor (USA), W. Saenger (Germany), N. Sharon (Israel), E. van Lenten (USA), E.C. Webb (Australia). American Chemical Society Committeefor Carbohydrate Nomenclature:D. Horton (Chairman), L. Anderson, D.C. Baker, H.H. Baer, J.N. BeMiller, B. Bossenbroek. R. W. Jeanloz, K.L. Loening, W. A. Szarek, R.S. Tipson, W.J. Whelan, R.L. Whistler. Corresponding Members ofttie ACS Committeef o r carbohydrate Nomenclature (other than JCBN and the expert panel): R.F. Brady (USA), J.S. Brimacombe (UK), J.G. Buchanan (UK), B. Coxon (USA), J. Defaye (France), N.K. Kochetkov (Russia), R.U. Lemieux (Canada), R.H. Marchessault (Canada), J.M. Webber (UK). Correspondence on these recommendations should be addressed to Dr. Alan D. McNaught at the above address or to any member of the Commission. Reproduced from Pure Appl. Chem., 1996, 68, 1919. 0 International Union of Pure and Applied Chenustry (IUPAC) 1996.
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NOMENCLATURE OF CARBOHYDRATES
NOMENCLATURE OF CARBOHYDRATES
(Recommendations 1996) Contents Preamble 2-Carb-0.Historical development of carbohydrate nomenclature 0.1. &Iy approaches 0.2. The contribution of Emil Fischer 0.3. Cyclic forms 0.4. Nomenclature commissions 2-Carb-1. Definitions and conventions 1.1. Carbohydrates 1.2. Monosaccharides (aldoses and ketoses) 1.3. Dialdoses 1.4. Diketoses 1.5. Ketoaldoses (aldoketoses) 1.6. Deoxy sugars 1.7. Amino sugars 1.8. Alditols 1.9. Aldonic acids 1.10. Ketoaldonic acids 1.1 1. Uronic acids 1.12. Aldaric acids 1.13. Glycosides 1.14. Oligosaccharides 1.15. Polysaccharides I . 16. Conventions for examples 2-Carb-2. Parent monosaccharides 2.1. Choice of parent structure 2.2. Numbering and naming of the parent structure 2-Carb-3. The Fischer projection of the acyclic form 2-Carb-4. Configurational symbols andprefixs 4.1. Use of D and L 4.2. The configurational atom 4.3. Configurational prefixes in systematic names 4.4.Racemates and meso forms 4.5. Optical rotation 2-Carb-5.Cyclic forms and their representation 5. I. Ring size 5.2. The Fischer projection 5.3. Modified Fischer projection 5.4. The Haworth representation 5.5. Unconventional Haworth representations 5.6. The Mills depiction 5.7. Depiction of conformation 5.8. Conformations of acyclic chains 2-Carb-6.Anomencforms; use of R and p 6.1. The anomeric centre 6.2. The anomeric reference atom and the anomeric configurational symbol 6.3. Mixtures of anomers 6.4. Use of a and p
NOMENCLATURE OF CARBOHYDRATES 2-Curb-7. Confonnafionof cyclic form 7.1. The conformational descriptor 7.2. Notation of ring shape 7.3. Notation of variants 7.4. Enantiomers 2-Carb-8. Aldoses 8.1. Trivial names 8.2. Systematic names 8.3. Multiple configurationalprefixes 8.4. Multiple sets of c h i d centres 8.5. Anomeric configuration in cyclic forms of higher aldoses 2-Carb-9. Dialdoses 2-Carb-10. Ketoses 10.1. Classification 10.2. Trivial names 10.3. Systematic names 10.4. Configurationalprefixes 2-Carb-11. Dikeroses 1I. 1. Systematic names 1 1.2. Multiple sets of c h i d centres 2-Curb-12.Ketoaldoses (aldoketoses, aldosuloses) 12.1. Systematic names 12.2. Dehydro names 2-Carb-13. Deoxy sugars 13.1. Trivial names 13.2. Names derived from trivial names of sugars 13.3. Systematic names 13.4. Deoxy alditols 2-Curb-14. Amino sugars 14. I . General principles 14.2. Trivial names 14.3. Systematic names 2-Carb-IS. Thio sugars and other chalcogen analogues 2 - Carb-I 6. Other subsriruted monosaccharides 16.1. Replacement of hydrogen at a non-terminal carbon atom 16.2. Replacement of OH at a non-terminal carbon atom 16.3. Unequal substitution at a non-terminal carbon atom 16.4. Terminal substitution 16.5. Replacement of carbonyl oxygen by nitrogen (imines, hydrazones, osazones etc.) t6.6. isotopic substitution and isotopic labelling 2-Curb-I7. Unsarurated monosaccharides 17.1. General principles 17.2. Double bonds 17.3. Triple bonds and cumulative double bonds 2-Curb-18.Branched-chainsugars 18.1. Trivial names 18.2. Systematic names 18.3. Choice of parent 18.4. Naming the branches 18.5. Numbering 18.6. Terminal substitution 2-Curb-19. Aldifols 19.1. Naming
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NOMENCLATURE OF CARBOHYDRATES
19.2.meso Forms 2-Curb-20. Aldonic ucids 20.1. Naming 20.2. Derivatives 2-Curb-21.Ketoaldonicacih 21.1. Naming 21.3. Derivatives 2-Carb-22. Uronic acids 22.1. Naming and numbering 22.2. Derivatives 2-Curb-23.Aldaric acids 23. I , Naming 23.2. meso Forms 23.3. Trivial names 23.4, Derivatives 2-Carb-24. 0-Substitution 24.1. Acyl (alkyl) names 24.2. Phosphorus esters 24.3. Sulfates 2-Carb-25.N-Substitution 2-Carb-26.Intramolecular anhydrides 2-Carb-27.Intermolecular anhydrides 2-Carb-28. Cyclic acetuls 2-Carb-29.Hemiacetals and hemithioacetals 2-Carb-30.Acetals, ketals and their thio analogues 2-Carb-3I . Namesfor monosaccharide residues 3 I . I . Glycosyl residues 31.2. Monosaccharides as substituent groups 31.3. Bivalent and tervalent residues 2-Curb-32. Radicals, cations and anions 2-Curb-33. Glycosidesand glycosyl compounds 33.1. Definitions 33.2. Glycosides 33.3. Thioglycosides. 33.4. Selenoglycosides 33.5. Glycosyl halides 33.6. N-Glycosyl compounds (glycosylamines) 33.7. C-Glycosyl compounds 2-Carb-34.Replacement of ring oxygen by other elements 34.1. Replacement by nitrogen or phosphorus 34.2. Replacement by carbon 2-Carb-35. Carbohydrates containing additional rings 35.1. Use of bivalent substituent prefixes 35.2. Ring fusion methods 35.3. Spiro systems 2-Carb-36.Disaccharides 36.1. Definition 36.2. Disaccharides without a free hemiacetal group 36.3. Disaccharides with a free hemiacetal group 36.4. Trivial names 2-Carb-37. Oligosaccharides 37.1. Oligosaccharides without a free hemiacetal group 37.2. Oligosaccharides with a free hemiacetal group
NOMENCLATURE OF CARBOHYDRATES
41
37.3. Branched oligosaccharides 37.4. Cyclic oligosaccharides 37.5. Oligosaccharide analogues 2-Carb-38. Use of symbolsfor defining oligosaccharide structures 38.1. General considerations 38.2. Representationsof sugar chains 38.3. The extended form 38.4. The condensed form 38.5. The short form 2-Carb-39. Polysaccharides 39.1. Names for hornopolysaccharides 39.2. Designation of configuration of residues 39.3. Designation of linkage 39.4. Naming of newly discovered polysaccharides 39.5. Uronic acid derivatives. 39.6. Amino sugar derivatives 39.7. Polysaccharides composed of more than one kind of residue 39.8. Substituted residues 39.9. Glycoproteins, proteoglycans and peptidoglycans References Appendix. Trivial Names for Carbohydrates,with their Systematic Equivalents Glossary of Glycose-basedTerms
Preamble These Recommendations expand and replace the Tentative Rules for Carbohydrate Nomenclature [l] issued in 1969 jointly by the IUPAC Commission on the Nomenclature of Organic Chemistry and the In-IUPAC Commission on Biochemical Nomenclature (CBN) and reprinted in [2]. They also replace other published JCBN Recommendations [3-71 that deal with specialized areas of carbohydrate terminology; however, these documents can be consulted for further examples. Of relevance to the field, though not incorporated into the present document, are the following recommendations: Nomenclature of cyclitols, 1973 [8] Numbering of atoms in myo-inositol, 1988 [9] Symbols for specifying the conformation of polysaccharide chains, 1981 101 Nomenclature of glycoproteins, glycopeptides and peptidoglycans, 1985 111 Nomenclature of glycolipids, in preparation [ 121 The present Recommendations deal with the acyclic and cyclic forms of monosaccharides and their simple derivatives, as well as with the nomenclature of oligosaccharides and polysaccharides. They are additional to the Definitive Rules for the Nomenclature of Organic Chemistry [13,14] and are intended to govern those aspects of the nomenclature of carbohydrates not covered by those rules.
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NOMENCLATURE OF CARBOHYDRATES
2-Carb-0. Historical development of carbohydrate nomenclature [151 2-Carb-0.1. Early approaches In the early nineteenth century, individual sugars were often named after their source, e.g. grape sugar (Traubenzucker) for glucose, cane sugar (Rohrzucker) for saccharose(the name sucrose was coined much later). The name glucose was coined in 1838; Kekult in 1866 proposed the name ‘dextrose’ because glucose is dextrorotatory, and the laevorotatory ‘fruit sugar’ (Fruchtzucker, fructose) was for some time named ‘laevulose’ (American spelling ‘levulose’). Very early, consensus was reached that sugars should be named with the ending ‘-ose’, and by combination with the French word ‘cellule’ for cell the term cellulose was coined, long before the structure was known. The term ‘carbohydrate’ (French ‘hydrate de carbone’) was applied originally to monosaccharides, in recognition of the fact that their ~. the term is now empirical composition can be expressed as C ~ H Z O )However used generically in a wider sense (see 2-Carb-1.1).
2-Carb-0.2. The contributionof Emil Fischer Emil Fischer [ 161 began his fundamental studies on carbohydrates in 1880. Within ten years, he could assign the relative configurationsof most known sugars and had also synthesized many sugars. This led to the necessity to name the various compounds. Fischer and others laid the foundations of a terminology still in use, based on the terms triose, tetrose, pentose, and hexose. He endorsed Armstrong’s proposal to classify sugars into aldoses and ketoses, and proposed the name fructose for laevulose, because he found that the sign of optical rotation was not a suitable criterion for grouping sugars into families. The concept of stereochemistry,developed since 1874 by van’t Hoff and L,e Bel, had a great impact on carbohydrate chemistry because it could easily explain isomerism. Emil Fischer introduced the classical projection formulae for sugars, with a standard orientation (carbon chain vertical, carbonyl group at the top); since he used models with flexible bonds between the atoms, he could easily ‘stretch’ his sugar models into a position suitable for projection. He assigned to the dextrorotatory glucose (via the derived glucaric acid) the projection with the OH group at C-5 pointing to the right, well knowing that there was a 50%chance that this was wrong. Much later (Bijvoet, 1951), it was proved correct in the absolute sense. Rosanoff in 1906 selected the enantiomeric glyceraldehydes as the point of reference; any sugar derivable by chain lengthening from what is now known as D,-glyceraldehydebelongs to the D series, a convention still in use.
2-Carb-0.3. Cyclic forms Towards the end of the nineteenth century it was realized that the free sugars (not only the glycosides) existed as cyclic hemiacetals or hemiketals. Mutarotation, discovered in 1846 by Dubrunfaut, was now interpreted as being due to a change
NOMENCLATURE OF CARBOHYDRATES
49
in the configuration of the glycosidic (anomeric) carbon atom. Emil Fischer assumed the cyclic form to be a five-membered ring, which Tollens designated by the symbol <1,4>, while the six-membered ring received the symbol <1,5>. In the 1920s,Haworth and his school proposed the terms ‘furanose’ and ‘pyranose’ for the two forms. Haworth also introduced the ‘Haworth depiction’ for writing structural formulae, a convention that was soon widely followed.
2-Carb-0.4. Nomenclature commissions Up to the 1940s, nomenclature proposals were made by individuals; in some cases they were followed by the scientific community and in some cases not. Official bodies like the International Union of Chemistry,though developing and expanding the Geneva nomenclature for organic compounds, made little progress with carbohydrate nomenclature. The IUPAC Commission on Nomenclature of Biological Chemistry put forward a classification scheme for carbohydrates, but the new terms proposed have not survived. However in 1939 the American Chemical Society (ACS) formed a committee to look into this matter, since rapid progress in the field had led to various misnomers arising from the lack of guidelines. Within this committee, the foundations of modern systematic nomenclature for carbohydrates and derivatives were laid: numbering of the sugar chain, the use of D and L and a and p, and the designation of stereochemistry by italicized prefixes (multiple prefixes for longer chains). Some preliminary communications appeared, and the final report, prepared by M.L. Wolfrom, was approved by the ACS Council and published in 1948 [ 171. Not all problems were solved, however, and different usages were encountered on the two sides of the Atlantic. A joint British-American committee was therefore set up, and in 1952 it published ‘Rules for Carbohydrate Nomenclature’ [18]. This work was continued, and a revised version was endorsed in 1963 by the American Chemical Society and by the Chemical Society in Britain and published [19]. The publication of this report led the IUPAC Commission on Nomenclature of Organic Chemistry to consider the preparation of a set of IUPAC Rules for Carbohydrate Nomenclature. This was done jointly with the IUPAC-IUB Commission on Biochemical Nomenclature, and resulted in the ‘Tentative Rules for Carbohydrate Nomenclature, Part I, 1969’, published in 1971/72 in several journals [ 11. It is a revision of this 1971 document that is presented here. In the present document, recommendations are designated 2-Carb-n, to distinguish them from the Carb-n recommendations in the previous publication.
2-Carb-1. Definitions and conventions 2-Carb-1.1. Carbohydrates The generic term ‘carbohydrate’ includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction
50
NOMENCLATURE OF CARBOHYDRATES
of the carbonyl group (alditols), by oxidation of one or more terminal groups to carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom, an amino group, a thiol group or similar heteroatomic groups. It also includes derivatives of these compounds. The term ‘sugar’ is frequently applied to monosaccharides and lower oligosaccharides. It is noteworthy that about 3% of the compounds listed by Chemical Abstracts Service (i.e. more than 360 OOO) are named by the methods of carbohydrate nomenclature. Note. Cyclitols are generally not regarded as carbohydrates. Their nomenclature is dealt with in other recommendations [8,9].
2-Carb-1.2. Monosaccharides Parent monosaccharides are polyhydroxy aldehydes H-[CHOHIn-CHOor polyhydroxy ketones H-[CHOH]n-CO-[CHOH]m-Hwith three or more carbon atoms. The generic term ‘monosaccharide’ (as opposed to oligosaccharide or polysaccharide) denotes a single unit, without glycosidic connection to other such units. It includes aldoses, dialdoses, aldoketoses, ketoses and diketoses, as well as deoxy sugars and amino sugars, and their derivatives, provided that the parent compound has a (potential) carbonyl group.
1.2.1. Aldoses and ketoses Monosaccharides with an aldehydic carbonyl or potential aldehydic carbonyl group are called aldoses; those with a ketonic carbonyl or potential ketonic carbonyl group, ketoses. Note. The term ‘potential aldehydic carbonyl group’ refers to the hemiacetal group arising from ring closure. Likewise, the term ‘potential ketonic carbonyl group’ refers to the
hemiketal structure (see 2-Carb-5). 1.2.2. Cyclic forms
Cyclic hemiacetals or hemiketals of sugars with a five-membered (tetrahydrofuran) ring are called furanoses, those with a six-membered (tetrahydropyran)ring pyranoses. For sugars with other ring sizes see 2-Carb-5.
2-Carb-1.3. Dialdoses Monosaccharides containing two (potential) aldehydic carbonyl groups are called dialdoses (see 2-Carb-9).
2-Carb-1.4. Diketoses Monosaccharides containing two (potential) ketonic carbonyl groups are termed diketoses (see 2-Carb-11).
NOMENCLATURE OF CARBOHYDRATES
51
2-Carb-1.5. Ketoaldoses (aldoketoses, aldosuloses) Monosaccharidescontaining a (potential)aldehydic group and a (potential)ketonic group are called ketoaldoses (see 2-Carb-12); this term is preferred to the alternatives on the basis of 2-Carb-2.1.1 (aldose preferred to ketose).
2-Carb-1.6.Deoxy sugars Monosaccharides in which an alcoholic hydroxy group has been replaced by a hydrogen atom are called deoxy sugars (see 2-Carb-13).
2-Carb-1.7 Amino sugars Monosaccharides in which an alcoholic hydroxy group has been replaced by an amino group are called amino sugars (see 2-Carb-14). When the hemiacetal hydroxy group is replaced, the compounds are called glycosylamines.
2-Carb-1.8. Alditols The polyhydric alcohols arising formally from the replacement of a carbonyl group in a monosaccharide with a CHOH group are termed alditols (see 2-Carb-19).
2-Carb-1.9. Aldonic acids Monocarboxylic acids formally derived from aldoses by replacement of the aldehydic group by a carboxy group are termed aldonic acids (see 2-Carb-20).
2-Carb-1.10.Ketoaldonic acids
0 x 0 carboxylic acids formally derived from aldonic acids by replacement of a secondary CHOH group by a carbonyl group are called ketoaldonic acids (see 2-Cab-21).
2-Carb-1.11.Uronic acids Monocarboxylicacids formally derived from aldoses by replacement of the CH20H group with a carboxy group are termed uronic acids (see 2-Carb-22).
2-Carb-1.12.Aldaric acids The dicarboxylicacids formed from aldoses by replacement of both terminal groups (CHO and CH20H) by carboxy groups are called aldaric acids (see 2-Carb-23).
2-Carb-1.13. Glycosides Glycosides are mixed acetals formally arising by elimination of water between the hemiacetal or hemiketal hydroxy group of a sugar and a hydroxy group of a second compound. The bond between the two components is called a glycosidic bond. For an extension of this definition, see 2-Cab-33.
52
NOMENCLATURE OF CARBOHYDRATES
2-Carb-1.14. Oligosaccharides Oligosaccharides are compounds in which monosaccharide units are joined by glycosidic linkages. According to the number of units, they are called disaccharides, trisaccharides, tetrasaccharides,pentasaccharides etc. The borderline with polysaccharides cannot be drawn strictly; however the term ‘oligosaccharide’ is commonly used to refer to a defined structure as opposed to a polymer of unspecified length or a homologous mixture. When the linkages are of other types, the compounds are regarded as oligosaccharide analogues. (See 2-Carb-37.) Note. This definition is broader than that given in [6],to reflect current usage.
2-Carb-1.15. Polysaccharides ‘Polysaccharide’ (glycan) is the name given to a macromolecule consisting of a large number of monosaccharide (glycose) residues joined to each other by glycosidic linkages. The term poly(g1ycose) is not a full synonym for polysaccharide (glycan) (cf. [20]), because it includes macromolecules composed of glycose residues joined to each other by non-glycosidic linkages.
For polysaccharides containing a substantial proportion of amino sugar residues, the term polysaccharide is adequate, although the term glycosaminoglycan may be used where particular emphasis is desired. Polysaccharides composed of only one kind of monosaccharide are described as homopolysaccharides (homoglycans). Similarly, if two or more different kinds of monomeric unit are present, the class name heteropolysaccharide (heteroglycan) may be used. (See 2-Carb-39.) The term ‘glycan’ has also been used for the saccharide component of a glycoprotein, even though the chain length may not be large. The term polysaccharide has also been widely used for macromolecules containing glycose or alditol residues in which both glycosidic and phosphate diester linkages are present. 2-Carb-1.16. Conventions for examples 1.16.1. Names of examples are given with an initial capital letter (e.g. ‘L-glyceroP-D-gluco-Heptopyranose’) to clarify the usage in headings and to show which letter controls the ordering in an alphabetical index.
1.16.2. The following abbreviations are commonly used for substituent groups in structural formulae: Ac (acetyl), Bn or PhCH2 (benzyl), Bz or PhCO (benzoyl), Et (ethyl), Me (methyl), Me3Si (not TMS) (trimethylsilyl), Bu‘MezSi (not TBDMS) (tert-butyldimethylsilyl), Ph (phenyl), Tf (triflyl = trifluoromethanesulfonyl), Ts (tosyl = toluene-p-sulfonyl), Tr (trityl).
NOMENCLATURE OF CARBOHYDRATES
53
2-Carb-2. Parent monosaccharides 2-Carb-2.1. Choice of parent structure In cases where more than one monosaccharide structure is embedded in a larger molecule, a parent structure is chosen on the basis of the following criteria, applied in the order given until a decision is reached: 2.1.1. The parent that includes the functional group most preferred by general principles of organic nomenclature [13,14]. If there is a choice, it is made on the basis of the greatest number of occurrences of the most preferred functional group. Thus aldaric acid > uronic acidketoaldonic acid/aldonic acid > dialdose > ketoaldose/aldose > diketose > ketose. 2.1.2. The parent with the greatest number of carbon atoms in the chain, e.g. a heptose rather than a hexose. 2.1.3. The parent with the name that comes first in an alphabetical listing based on: 2.1.3.1. the trivial name or the configurational prefix(es) of the systematic name, e.g. allose rather than glucose, a gluco rather than a gulo derivative; 2.1.3.2. the configurational symbol D rather than L ; 2.1.3.3. the anomeric symbol 01 rather than p. 2.1.4. The parent with the most substituents cited as prefixes (bridging substitution, e.g. 2,3-O-methylene, is regarded as multiple substitution for this purpose). 2.1.5. The parent with the lowest locants (see [ 141, p. 17) for substituent prefixes. 2.1.6. The parent with the lowest locant for the first-cited substituent. The implications of these recommendations for branched-chain structures are exemplified in 2-Carb- 18. Note 1. To maintain homomorphic relationships between classes of sugars, the (potential) aldehyde group of a uronic acid is regarded as the principal function for numbering and naming (see 2-Carb-2.2.I and 2-Cab-22).
Note 2. To maintain integrity of carbohydrate names, it is sometimes helpful to overstep the strict order of principal group preference specified in general organic nomenclature [ 13,141. For example, a carboxymethyl-substituted sugar can be named as such, rather than as an acetic acid derivative (see 2-Carb-31.2).
2-Carb-2.2. Numbering and naming the parent structure The basis for the name is the structure of the parent monosaccharide in the acyclic form. Charts I and IV (2-Carb-10) give trivial names for parent aldoses and ketoses with up to six carbon atoms. 2-Carb-8.2 and 2-Carb-10.3 describe systematic naming procedures.
CHO H-C-OH CH2OH D-Glyceraldehyde D-g.!yCerO
$HO H-C-OH H-C-OH CHpOH D-Erythrose D-efyihro FHO H-C-OH H-C-OH H-C-OH CH20H 0-R i se 0-nbo
(0-Rib) FHO H-C-OH H-?-OH H-C-OH H-C-OH CHpOH D-Allose D-all0 (0-All)
$HO HO-C-H H-C'OH CHpOH D-Thrmse
0-thre0 FHO HO-C-H H-C-OH H-C-OH CH2OH D-Arabinose 0-arabino (D-A~)
CHO $HO H-C-OH HO-C-H H-C-OH HO-C-H H-C-OH H-C-OH H-C-OH H-C-OH CHPOH CHpOH D-Altmse 0-Glucose D-gIUCU D-altro (0-Alt) (0-Glc)
CHO HO-C+I HO-C-H H-C-OH H-C-OH CHpOH 0-Mannose D-manno (0-Man)
CHO H-C-OH HO-C-H H-C-OH CHpOH D-Xylose
FHO HO-C-H HO-C-H H-C-OH CHpOH D-Lyxose D-kXO (D-LYX)
O-.%Y/O
(D-xYl)
FHO H-C-OH H-C-OH HO-C-H H-C-OH CHpOH D-Gulose O-gU/O (D-GuI)
CHO HO-C-H H-C-OH HO-C-H H-C-OH CHpOH D-ldose
Dido
(0-ldo)
$HO H-C-OH HO-C-H HO-C-H H-CeOH CH2OH DCalactose D-galac!o (D-Gal)
CHO HO-C-H HO-C-H HO-C-H H-C-OH CHpOH 0-Talose D-talo (D-Tal)
Chart I. Trivial names (with recommended three-letter abbreviationsin parentheses)and structures(in the aldehydic, acyclic form) of the aldoses with three to six carbon atoms. Only the D-forms are shown; the L-forms are the mirror images. The chains of chiral atom delineated in bold face correspond to the configurational prefixes given in italics below the names
55
NOMENCLATURE OF CARBOHYDRATES
2.2.1. Numbering
The carbon atoms of a monosaccharide are numbered consecutively in such a way that: 2.2.1.1. A (potential) aldehyde group receives the locant 1 (even if a senior function is present, as in uronic acids; see 2-Carb-2.1, note 1); 2.2.1.2. The most senior of other functional groups expressed in the suffix receives the lowest possible locant, i.e. carboxylic acid (derivatives) > (potential) ketonic carbonyl groups. 2.2.2. Choice of parent name
The name selected is that which comes first in the alphabet (configurational prefixes included). Trivial names are preferred for parent monosaccharides and for those derivatives where all stereocentres are stereochemically unmodified. Examples:
CHzOH HOYH
J
HYOH FH1OH
HOYH
L-gluco
-
c=o
HOFH HFOH
HOYH
HOFH HOFH
HOYH
CHZOH
]
L-erythro -
CH,OH
~-erythroi-gluceNon-5-ulose not D-fhreeD-a//enon-5-ulose
L-Glucitol not D-gulitol
2.2.3. Choice between alternative names for substituted derivatives
When the parent structure is symmetrical, preference between alternative names for derivatives should be given according to the following criteria, taken in order: 2.2.3.1. The name including the configurational symbol D rather than L. Example: CHpOH
H+H HOFH HFOMe CHpOH
4-OMethyl-D-xylitol not 2-O-methyl-~-xylitol
NOMENCLATURE OF CARBOHYDRATES
56
2.2.3.2. The name that gives the lowest set of locants (see [14], p. 17) to the substituents present. Example:
CHpOH I MeOCH I
MeOCH
HCOH I
HCOMe CHpOH
2,3,BTri-Omethyl-D-mannitol not 2,4,5-tri-Omethyl-o-rnannitol
2.2.3.3. The name that, when the substituents have been placed in alphabetical order, possesses the lowest locant for the first-cited substituent. Example: YH20H AdFH HOFH HYOH HYOMe CHPOH
2-OAcetyl-5-Omethyl-o-mannitol not 5-OacetylB-Omethyl-~-rnannitol
2-Curb-3. The Fischerprojection of the acyclicform In this representation of a monosaccharide, the carbon chain is written vertically, with the lowest numbered carbon atom at the top. To define the stereochemistry, each carbon atom is considered in turn and placed in the plane of the paper. Neighbouring carbon atoms are below, and the H and OH groups above the plane of the paper (see below).
I
H-C-OH
I
(a)
(c)
(4
(1)
f
I I
H-C-OH
(d)
(9)
Conventional representationof a carbon atom (e.g. (3-2 of D-glucose) in the Fischer projection. Representation (e) will be used in general in the present document.
NOMENCLATURE OF CARBOHYDRATES
51
The formula below is the Fischer projection for the acyclic form of D-glucose. The Fischer projections of the other aldoses (in the acyclic form) are given in Chart I (2-Cub-2.2). ’CHO
21
51
HCOH 61
CHpOH
D-Glucose
Note. The Fischer projection is not intended to be a true representation of conformation.
2-Cwb-4. Configurationalsymbols and prejkes
2-Carb-4.1. Use of D and L The simplest aldose is glyceraldehyde (occasionally called glyceral [2 11). It contains one centre of chirality (asymmetric carbon atom) and occurs therefore in two enantiomeric forms, called D-glyceraldehydeand L-glyceraldehyde;these are represented by the projection formulae given below. It is known that these projections correspond to the absolute configurations. The configurational symbols D and L should appear in print in small-capital roman letters (indicated in typescript by double underlining) and are linked by a hyphen to the name of the sugar. CHO H-C-OH
CHO
HO-C-H
CH,OH
D-Glyceraldehyde
CH~OH
L-Glyceraldehyde
2-Carb-4.2. The configurational atom A monosaccharideis assigned to the D or the L series according to the configuration at the highest-numbered centre of chirality.This asymmetrically substituted carbon atom is called the ‘configurationalatom’. Thus if the hydroxy group (or the oxygen bridge of the ring form; see 2-Carb-6) projects to the right in the Fischer projection, the sugar belongs to the D series and receives the prefix D-. Examples: YHO HYOH HOYH HYOH HYOH CHpOH
D-Glucose
YHO HYOH
HOYH
HYOH CHpOH
D-Xylose
NOMENCLATURE OF CARBOHYDRATES
58
CHpOH I
c=o I
HOFH HCOH I HYOH CHpOH
D-arabino-Hex-2-ulose (D-Fructose)
YHO H T H H T H HYOH H T H HYOH CHpOH
o-glycero-L-gulo-Heptose D Monosaccharides
CHO I
HTH HYOH HOCH I
HOCH I
CHpOH
L-Glucose
YHO HYOH HYH HYH CHpOH
L-Arabinose YHO H T H HOCH
YHpOH
c=o I
HOFH HYOH
H~OH HYOH H T H CHpOH
HYH CHpOH
~-xy/eHexQ-ulose (L-Sorbose)
L-glycerGD-manneHeptose L Monosaccharides
2-Carb-4.3. Configurational prefixes in systematic names In the systematic names of sugars or their derivatives, it is necessary to specify not only the configuration of the configurational atom but also the configurationsof all CHOH groups. This is done by the appropriate configurational prefix. These prefixes are derived from the trivial names of the aldoses in Chart I (relevant portions of the structures are delineated in bold face). In monosaccharides with more than four asymmetrically substituted carbon atoms, where more than one configurational prefix is employed (see 2-Carb-8.3), each group of asymmetrically substituted atoms represented by a particular prefix has its own configurational symbol, specifying the configuration (D or L) of the highest numbered atom of the group.
NOMENCLATURE OF CARBOHYDRATES
59
The configurational prefixes are printed in lower-case italic (indicated in typescript by underlining), and are preceded by either D- or L-,as appropriate. For examples see 2-Carb-4.2 and 2-Carb-6.2 Note. In cyclic forms of sugars, the configuration at the anomeric chiral centre is defined in relation to the ‘anomeric reference atom’ (see 2-Carb-6.2).
2-Carb-4.4.
Racemates and meso forms
Racemates may be indicated by the prefix DL-. Structures that have a plane of symmetry and are therefore optically inactive (e.g. erythritol, galactitol) are called meso forms and may be given the prefix ‘meso-’.
2-Carb-4.5.
Optical rotation
If the sign of the optical rotation under specified conditions is to be indicated, this is done by adding (+)- or (-)- before the configurational prefix. Racemic forms are indicated by @)-. Examples: D-Glucose or (+)-D-glucose D-Fructoseor (-)+-fructose DL-Glucose or (+_)-glucose
2-Carb-5. Cyclic forms and their representation 2-Carb-5.1. Ring size Most monosaccharides exist as cyclic hemiacetals or hemiketals. Cyclic forms with a three-membered ring are called oxiroses, those with a four-membered ring oxetoses, those with a five-membered ring furanoses, with a six-membered ring pyranoses, with a seven-membered ring septanoses, with an eight-membered ring octanoses, and so on. To avoid ambiguities, the locants of the positions of ring closure may be given; the locant of the carbonyl group is always cited first, that of the hydroxy group second (for relevant examples of this see 2-Carb-6.4). Lack of ring size specification has no particular implication. Note. The ‘0’of oxirose, oxetose, and octanose is not elided after a prefix ending in
‘0’
Example: Nonooctanose, not nonoctanose.
If it is to be stressed that an open-chain form of an aldose is under consideration, the prefix ‘aldehydo-’ may be used. For ketoses, the prefix is ‘keto-’ 2-Carb-5.2. The Fischer projection If a cyclic form of a sugar is to be represented in the Fischer projection, a long bond can be drawn between the oxygen involved in ring formation and the (anomeric)
NOMENCLATURE OF CARBOHYDRATES
60
carbon atom to which it is linked, as shown in the following formulae for cyclic forms of or-D-glucose (see 2-Carb-6 for the meaning of CL and p):
'7
HYOH HCO-
HYOH
I
HOCH I
HOFH
I OCH
HYOH
HCOH
HYO
HYOH
HCOH
HCOH
CHzOH
a-D-Glucooxirose
I
I
I
I
CH,OH
CH20H
a-o-Glucooxetose
a-D-GlUCOfUranOSe
I
HYOH
HCOH
HYOH
H+OH
HOYH
HOCH I
HYO HYOH
HCOH H+OH
CHpOH
CHiO
a-D-Glucopyranose
a-D-Glucoseptanose
2-Carb-5.3.Modified Fischer projection To clarify steric relationships in cyclic forms, a modified Fischer projection may be used. The carbon atom bearing the ring-forming hydroxy group, C-n (C-5 for glucopyranose) is rotated about its bond to C-(n - 1) (C-4 for glucopyranose) in order to bring all ring atoms (including the oxygen) into the same vertical line. The oxygen bridge is then represented by a long bond; it is imagined as being behind the plane of the paper. Examples are given below.
1 HCOH I
HCOAc HCOH HOCHp-CH
I
AcOyH P A C HC-+H I CH~OAC
HC-CHj
p a-D-GlUCOpyranOSe
2,3,5,6-Tetra-Qacetyla-D-galactofuranose
P-L-Fucopyranose
61
NOMENCLATURE OF CARBOHYDRATES
HOCH,-CH
I I
n
P-D-Fructofuranose
Thus the trans relationship between the hydroxymethyl group and the C-1 hydroxy group in a-D-glucopyranose,and the cis relationship between the methyl group and the C-1 hydroxy group in P-L-fucopyranose, are clearly shown. Note that representation of ketoses may require a different modification of the Fischer projection, as shown in the fructofuranose example above. Here C-2 is rotated about the bond with C-3 to accommodate the long bond to C-2 from the oxygen at C-5. 2-Carb-5.4 The Haworth representation This is a perspective drawing of a simplified model. The ring is orientated almost perpendicular to the plane of the paper, but viewed from slightly above so that the edge closer to the viewer is drawn below the more distant edge, with the oxygen behind and C-1 at the right-hand end. To define the perspective, the ring bonds closer to the viewer are often thickened. The following schematic representation of pyranose ring closure in D-glucose shows the reorientation at C-5 necessary to allow ring formation; this process corresponds to the change from Fischer to modified Fischer projection. 1
CHO I
HYOH
HTH
-
HYOH HYOH 6CH20H
H
OH
H
H
OH
OH
Haworth representation of o-glucopyranose
NOMENCLATURE OF CARBOHYDRATES
62
The orientation of the model described above results in a clockwise numbering of the ring atoms. Groups that appear to the right of the modified Fischer projection appear below the plane of the ring; those on the left appear above. In the common Haworth representation of the pyranose form of D-aldohexoses, C-6 is above the plane. Generally, the configuration at the centre that yields the ring oxygen determines whether the rest of the carbon chain is below or above the plane of the ring. Examples (for the use of a and p see 2-Carb-6):
CH2OH 5
Fischer
modified Fischer
Haworth
P-L-Arabinofuranoserepresentations
J3-D-Ribopyranose
P-o-Ribofuranose5-phosphate
H
HYOH HYOH CH20
OH
HO
H
a+-Fructofuranose 1,6-bisphosphate
a-D- fructopyranose I HYOMe
HOYH HYOH HYOH HYOH
-
=
H
H Q ! Me HO
OH H
CH,O
Methyl a-D-glucoseptanoside
NOMENCLATURE OF CARBOHYDRATES
v
63
CH20H I
HoyH
HOYH
HOCH
I HOCH
OH
I
H
CH2OH
Methyl a-L-altrooxetoside
H
Methyl 0-o-allooxiroside
Note. In writing Haworth formulae, the H atoms bound to the carbon atoms of the ring are often omitted to avoid crowding of the lettering in the ring. For the sake of clarity, the form with H atoms included is preferred in this document.
2-Carb-5.5. Unconventional Haworth representations It is sometimes desirable to draw Haworth formulae with the ring in other orientations (see Chart 11), when there are bulky substituents to be represented, or when linkages in oligo- or poly-saccharides are to be shown. If the ring is inverted [as in (g)-(I)], the numbering runs counterclockwise.
2-Carb-5.6. The Mills depiction In some cases, particularly where additional rings are present, structural formulae can be clarified by use of the Mills depiction. Here the main hemiacetal ring is drawn in the plane of the paper; dashed bonds denote substituentsbelow this plane, and thickened bonds those above. Examples:
1,2:3,4-Di-Oisopropylidene-a-o-galactopyranose
D-Glucaro-l,4:6,3-dilactone
2-Carb-5.7. Depiction of conformation The Haworth representation implies a planar ring. However, monosaccharides assume conformations that are not planar: these may be represented by Haworth conformational formulae. The nomenclature of conformations is described in 2-Carb-7. For example, ~-D-glucopyranoseassumes a chair conformation:
NOMENCLATURE OF CARBOHYDRATES
64
Chart 11. P-D-Glucopyranose in the twelve possible Haworth representations (the hydrogen atoms are frequently omitted) CHPOH 0 HO
OH
H
H O o -H
OH
H
P-D-Glucopyranosein a chair conformation
Note. The hydrogen atoms bonded to carbon are frequently omitted, but their inclusion may be necessary to make a stereochemical point.
NOMENCLATURE OF CARBOHYDRATES
65
2-Carb-5.8. Conformations of acyclic chains Conformational depictions of acyclic sugar chains are conveniently expressed by locating certain atoms in the plane of the paper and orientating the remaining atoms or groups appropriately above and below that plane, as shown for D-arabinitol and xylitol (it should be recognized that the favoured conformation does not necessarily have all the carbon atoms in the same plane):
o-Arabinitol
Xylitol
2-Curb-6.Anomericforms; use of a and 2-Carb-6.1. The anomeric centre The new centre of chirality generated by hemiacetal ring closure is called the anomeric centre. The two stereoisomers are referred to as anomers, designated ct or p according to the configurational relationship between the anomeric centre and a specified anomeric reference atom.
2-Carb-6.2. The anomeric reference atom and the anomeric configurational symbol (aor p) The anomeric reference atom is the configurational atom (see 2-Carb-4.2 and 4.3) of the parent, unless multiple configurational prefixes (see 2-Carb-8.3) are used. If multiple configurational prefixes are used, the anomeric reference atom is the highest-numbered atom of the group of chiral centres next to the anomeric centre that is involved in the heterocyclic ring and specified by a single configurational prefix. In the ct anomer, the exocyclic oxygen atom at the anomeric centre is formally cis, in the Fischer projection, to the oxygen attached to the anomeric reference atom; in the p anomer these oxygen atoms are formally trans. The anomeric symbol a or p, followed by a hyphen, is placed immediately before the configurational symbol D or L of the trivial name or of the configurationalprefix denoting the group of chiral carbon atoms that includes the anomeric reference atom.
NOMENCLATURE OF CARBOHYDRATES
66
Examples: HOC,H HYOH HOYH
HOYH
-
+HCO CHZOH
HO HCO
OH
H
Ho VH20H
1
CH20H
H
OH
a-D-gluco a-D-Glucopyranose
P-~-threo Methyl P-L-threofuranoside
a-L-arabino Methyl a-L-arabinopyranoside 7 HfOH
-
I
Ho HYOH CH20H
I
H
OH
CH20H
P-0-galacto Methyl P-D-galactofuranoside
CH2OH
HCOMe HOYH
-
HYOH HCO
3 HO+H
~
OH
HfOH
0
HO
OM* H
; $ T ] =+M HCO
H
CHpOH
OH
H
CHZOH
L-giycerea-D-manno Methyl L-glycerea-D-mannoheptopyranoside
P-D-arabino Methyl P-D-fructofuranoside
NOMENCLATURE OF CARBOHYDRATES
67
I c - C O O M e
H+OH
CHZOH
D-glycero-P-D-galacto Methyl 5-acetamido-3,5-dideoxy-~-glycefo-~-~-galacto-non-2-ulopyranosonate (see 2-Carb-14.2)
+ denotes the anorneric reference atom; 3 denotes the configurational atom. Note. For simple aldoses up to aldohexoses, and ketoses up to hept-2-uloses, the anomeric reference atom and the configurational atom are the same.
2-Carb-6.3. Mixtures of anomers In solution, most simple sugars and many of their derivatives occur as equilibrium mixtures of tautomers. The presence of a mixture of two anomers of the same ring size may be indicated in the name by the notation a$-, e.g. a,p-D-glucose. In formulae, the same situation can be expressed by separating the representation of the ligands at the anomeric centre from the a and p bonds [see examples (a) and (c)], or by use of a wavy line [(b) and (d)] (particularly if hydrogen atoms are omitted). Examples:
CHPOH
H
OH (a)
a$-D-Glucopyranose
'0iOoCH
op0,2-
H
OP032'
HO
CH,OH,OH or
H
HO
H HO
H
(4
HO
H
(d)
a$-D-Fructofuranose 6-phosphate
NOMENCLATURE OF CARBOHYDRATES
68
2-Carb-6.4. Use of a and p The Greek letters a and p are applicable only when the anomeric carbon atom has a lower locant than the anomeric reference atom. In the case of dialdoses (cf. 2-Carb-9), some diketoses (cf. 2-Carb- 11) and aldoketoses (cf. 2-Carb-12), ring closure is also possible in the other direction, i.e. of a carbonyl group with a higher locant than the reference carbon atom with a hydroxy group having a lower locant. In this case, the configuration of the anomeric carbon atom is indicated by the appropriate symbol R or S according to the sequence rule (cf. Section E in [ 131). Examples: 1
CHO
(6S)-1,2-Olsopropylidene-a-~-g/uc~hexodialdo-1,4:6,3-difuranose Note that locant numerals (potential carbonyl first) may be needed before the ring-size suffix in such cases.
2-Carb-7.Conformation of cyclic forms* 2-Carb-7.1. The conformational descriptor The conformation, i.e. the (approximate) spatial arrangement of the ring atoms of a monosaccharide in the cyclic form, may be indicated by an italic capital letter designating the type of ring shape, and numerals, distinguishing the variants. The
* This is an abridged version of the document ‘ConformationalNomenclature for Five- and Six-membered Ring Forms of Monosaccharidesand their Derivatives. Recommendations 1980 [3].
NOMENCLATURE OF CARBOHYDRATES
69
conformational descriptor is joined to the end of the name of the monosaccharide by a hyphen. Example:
2-Carb-7.2. Notation of ring shape The appropriate letters are as follows. Five-membered rings: E for envelope and T for twist; six-membered rings: C for chair, B for boat, S for skew, H for half-chair, and E for envelope. Examples are given in Chart 111.
2-Carb-7.3. Notation of variants The variants are distinguished by the locants of those ring atoms that lie outside a reference plane (defined below) and are listed for some examples in Table 1. The locants of ring atoms that lie on the side of the reference plane from which numbering appears clockwise (i.e. the upper side in the normal Haworth representation of furanoses and pyranoses) are written as superscripts and precede the letter; those that lie on the other side are written as subscripts and follow the letter. Heteroatoms (e.g. 0, S ) are indicated by their subscript or superscript atomic symbols. Table 1 gives the notations and Chart I11 some examples. Six-membered rings Chairs. The reference plane is defined by two parallel ring sides, so chosen that the lowest-numbered carbon atom in the ring is exoplanar (examples 5 and 6). Bouts. The reference plane is defined by the two parallel ‘sides’ of the boat (examples 7 and 8). Skews. Each skew form has two potential reference planes, containing three adjacent atoms and the remaining non-adjacent atom. The reference plane is so chosen that the lowest-numbered carbon atom in the ring, or the atom numbered next above it, is exoplanar, in that order of preference (examples 9 and 10).
Hulj-chairs. The reference plane is defined by the four adjacent coplanar atoms (example 11). Envelopes. The reference plane is defined by the five adjacent coplanar atoms (example 12). Five-membered rings Envelopes. The reference plane is defined by the four adjacent coplanar atoms (examples 1 and 2).
Table 1. Conformations and their notations; some examples are shown in Chart III
4
0
Type of sugar
Conformation
Aldofuranose Aldofuranose Aldofuranose
Atoms of reference plane Above plane
Below plane
envelope
0-4,C-I,C-3,C-4
c-2
envelope
C-1,C-2,C-4,0-4
c-3
twist
C-1,0-4,C-4
c-3
Notation
Example
E2
1
3E
2
c-2
3
3
T2
Aldofuranose
twist
C-3,C-4,0-4
c-2
C-1
2
TI
4
Aldopyranose
chair
C-2,C-3,C-5,0-5
c-4
C-1
4cI
5
F'yranoid lactone
chair
C-2,C-3,C-5,0-5
c-1
c-4
'c4
6
Aldopyranose
boat
0-5,C1,C-3,C-4
c-2,c-5
2.58
7
Aldopyranose
boat
C-2,C-3,C-5,0-5
B1.4
8
c-3
1
9
0-5
2
10
s-5
5
11
5E
12
Aldopyranose Aldopyranose Aldopyranose F'yranoid lactone
skew
skew half-chair envelope
C-2,C-4,C-5,0-5
c-1,c-3,c-4,c-5
c-1 $2-4 C-1
c-2
c-5 C-l,C-2,C-3,C-4,0-5 c-5 c-1.c-2,c-3,c-4
s3
so Hs
71
NOMENCLATURE OF CARBOHYDRATES H
H
4
2
3
5
6
HOCH
I
\ OH
HO
H
H 0
7
9
Hoa H
H
H
0
OCH3
HO
10
11
12
1 Methyl P-~-arabhofuranoside-E2 2 a-~-Arabinofuranose-~E 3 1,2-O-Isopropylidene-P-~-idofuranose-~T~ 4 2,3-O-Isopropylidene-u-~lyxofuranose- Ti 5 a-~-Arabinopyranose-~C~ 6 L-Glucono-1,S-lactone-'Cd 7 Methyl 2,6-anhydro-a-~-altropyranoside-~%8 1,4-Anhydro-a-~-allopyranose-B 1.4 9 1,2-0-Ethylidene-a-~-glucopyranose-'S~ 10 P-L-Altropyranose-2So 11 Methyl 2,3-anhydro-5-thio-P-~-lyxopyranoside-~Hs 12 2,3-Dideoxy-~-erythro-hex-2-enono1,s-lactone-5E
Chart 111. Drawings of the conformations listed in Table 1. T h e reference plane is stippled.
72
NOMENCLATURE OF CARBOHYDRATES
Twists.The reference plane is defined by three adjacent ring-atoms, so chosen that the exoplanar atoms lie on opposite sides of the plane (examples 3 and 4). Note 1. Many of the possible conformations are not likely to contribute significantly to the chemistry of a particular monosaccharide, but must be stabilized by formation of additional rings, as in anhydrides or other derivatives. Some others may occur as transition-state intermediates. Note 2. A more precise specification of conformation can be achieved by use of the Cremer-Pople puckering parameters [22].
2-Carb-7.4. Enantiomers The conformational symbols for enantiomers are different. It is therefore important to state in the context whether the D or the L form is under consideration. Enantiomers have the same reference plane (see 2-Carb-7.3 , and it should be noted that the mirror image of a-D-glUCOSe-4Ci is a-L-glucose- C4.
I'
HO H
OH OH
H mirror plane
HO H
H
Mirror images: a-~-glucopyranose-~C~ (upper) and a-L-glucopyranose-' C4 (lower)
2-Carb-8. Aldoses 2-Carb-8.1. Trivial names The aldoses with three to six carbon atoms have trivial names which are given, together with the formulae in the Fischer projection, in Chart I (2-Carb-2.2). (See also the alphabetical listing of trivial names in the Appendix.) The trivial names form the basis of the configurational prefixes (see 2-Carb-4.3).
2-Carb-8.2. Systematic names Systematic names are formed from a stem name and a configurational prefix or prefixes. The stem names for the aldoses with three to ten carbon atoms are triose,
NOMENCLATURE OF CARBOHYDRATES
73
tetrose, pentose, hexose, heptose, Octose, nonose, decose. The chain is numbered so that the carbonyl group is at position 1. The configuration of the CHOH groups of the sugar is designated by the appropriate configurational prefix(es) from Chart I. When used in systematic names, these prefixes are always to be in lower case letters (with no initial capital), and italicized in print. Each prefix is qualified by D or L (Chart I shows only the D structures). Examples: D-ribd'entose for D-ribose D-rnannd-iexose for D-mannose.
The trivial names are preferred for the parent sugars and for those derivatives where all stereocentres are unmodified. 2-Carb-8.3. Multiple configurational prefives An aldose containing more than four chiral centres is named by adding two or more configurationalprefixes to the stem name. Prefixes are assigned in order to the chiral centres in groups of four, beginning with the group proximal to C-1. The prefix relating to the group of carbon atom(s) farthest from C-1 (which may contain less than four atoms) is cited first. Examples: HC=O Hq=O
HCOH
1
HYOH H~OH
t
0-manno
J
HYOH
L-rib0
,$OH
0-glycero
CH,OH
D-gtycercm-gluco-Heptose not D-glUCcFD-glycefcFheptOSe
HOYH
CHPOH
L-ribo-D-manneNonose not D-mann0-L-rib~nOnoSe
2-Carb-8.4. Multiple sets of chiral centres If sequences of chiral centres are separated by non-chiral centres, the non-chiral centres are ignored, and the remaining set of chiral centres is assigned the appropriate configurationalprefix (for four centres or less) or prefixes (for more than four centres).
NOMENCLATURE OF CARBOHYDRATES
74
Example:
CHO
I
HYOH
HYOH HO$H
J
HOFH HYoH
I
L.‘hreO
CH,OH
3,SDideoxy-~threm- taledecose
Note 1. This convention is not needed for parent aldoses, only for deoxy aldoses, ketoses and similar compounds (see 2-Carb-10.4 and 2-Carb-11.2). Note 2. Since all aldoses up to the hexoses have trivial names that are preferred, the systematic names apply only to the higher aldoses. However, the configurational prefixes are also used to name ketoses (see below) and other monosaccharides.
2-Carb-8.5. Anomeric configuration in cyclic forms
For the specification of 01 and p in cyclic forms see 2-Carb-6. 2-Carb-9. Dialdoses Systematic names for individual dialdoses are formed from the systematic stem name for the corresponding aldose (see 2-Carb-8.2), but with the ending ‘odialdose’ instead of ‘ose’, and the appropriate configurational prefix (Chart I). A choice between the two possible aldose parent names is made on the basis of 2-Carb-2.2.2. Examples: CHO
H$OH YHO
HOYH
HCOH
HOYH
HO~H
HYOH
CHO
CHO
L- threcFTetrodialdose
galacfc-Hexodialdose
Note. The prefix ‘meso-’ could be included in the latter case, but it is not needed to define the structure.
If a cyclic form is to be named, the locants of the anomeric centre and of the carbon atom bearing the ring oxygen atom must be given (in that order) (cf. 2-Carb-6.4). If there is more than one ring size designator, they are placed in alphabetical order (e.g. furanose before pyranose).
NOMENCLATURE OF CARBOHYDRATES
Examples: “O@rHoOH HoH*
OH
OH
Methyl a-o-gluc~hexodialdo-6,3-furanose-1 ,!j-pyranoside
2-Curb-10.Ketoses 2-Carb-10.1. Classification Ketoses are classified as 2-ketoses, 3-ketoses, etc., according to the position of the (potential) carbonyl group. The locant 2 may be omitted if no ambiguity can arise, especially in a biochemical context.
2-Carb-10.2.Trivial names Ketoses with three to six carbon atoms are shown in Chart IV,with trivial names (and three-letter abbreviations)in parentheses. (See also the alphabetical listing of trivial names in the Appendix.) The trivial names ‘D-erythrulose’ for D-glycero-tetrulose, ‘D-ribulose’ for Deryfhro-pent-2-ulose, and ‘D-XylUlOSe’ for D-rhreo-pent-2-dose contain stereochemical redundancy and should not be used for naming derivatives. Sedoheptulose is the accepted trivial name for D-ah-hept-2-ulose.
2-Carb-10.3.Systematic names The systematic names are formed from the stem name and the appropriateconfigurational prefix. The stem names are formed from the corresponding aldose stem names (2-Cab-8.2) by replacing the ending ‘-ose’ with ‘-ulose’, preceded by the locant of the carbonyl group, e.g. hex-3-dose. The chain is numbered so that the carbonyl group receives the lowest possible locant. If the carbonyl group is in the middle of a chain with an odd number of carbon atoms, a choice between alternativenames is made according to 2-Cub-2.2.2. Note. In Chemical Abstracts Service (CAS) usage the locant for the carbonyl group precedes the stem name, e.g. 3-hexulose.
NOMENCLATURE OF CARBOHYDRATES
16
For examples see 2-Cab-10.4. VHzOH
$=O CHzOH 1, 3-Dihydroxyacetone VH20H
?=O HVOH CHzOH o-g/ycero-Tetrulose
('0-Erythrulose') VHzOH
VHZOH
?=O
$=O
HVOH HqOH CHzOH D-erylbmPent-2-ulose ('0-Ribulose'; D-Rul)
HFH HVOH CHzOH 0-tbrmPent-2-ulose ('D-XylUlOSe'; D-Xul)
9H2OH
VHzOH
VHzOH
?=O
$=O
$=O
$=O
HVOH HFOH HVOH CHZOH
H F H HVOH HqOH CHzOH
HVOH HOCH HYOH CHBOH
HFH HFH HYOH CHPOH
MbHex-2-ulose (D-Psicose; 0-Psi)
VHzOH
D-arabimHex-2-uIose 0-xybHex-Z-ulose (0-Fructose;0-Fru) (0-SoftJose; 0-Sor)
D-/yxo-Hex-2-ulose (D-Tagatose; o-Tag)
Chart IV.Structures, with systematicand trivial names, of the 2-ketoses with three to six carbon atoms 2-Carb-10.4. Configurational prefixes For 2-ketoses, configurational prefixes are given in the same way as for aldoses (see 2-Carb-8.2 and 2-Carb-8.3). Examples: CHzOH
c=o I H T H HYOH
HO?i
CHzOH
c=o I
HOFH HtOH HtOH HYOH
CHZOH
CHzOH
~-xy/o-Hex-2-ulose
~-a/tro-Hept-2-ulose
(L-Sorbose)
(D-Sedoheptulose)
NOMENCLATURE OF CARBOHYDRATES
77
CHpOH
c=o I
H T H H T H HYOH CHzOH OH
HYOH HOqH
OH
CH20H
~-g/ycereo-manno-Oct-2-ulose
o-a/treHept-2-ulopyranose
For ketoses with the carbonyl group at C-3 or a higher-numbered carbon atom, the carbonyl group is ignored and the set of chiral centres is given the appropriate prefix or prefixes according to Chart I (cf. 2-Carb-8.4). Examples: YHzOH
YH20H
HTH
HYOH
c=o I
c-0 HYOH
HOflH
HYOH
HYOH
CHzOH
CHzOH
~-arabineHex9-ulose
~-xy/~Hex-3-ulose not ~-xy/o-hex-Culose FH2OH HCOH
CH20H HTH HYOH
HYOH
c=o HTH
HYOH
HOYH CH20H
HOFH CHzOH
~-g/uceHept-4-ulose not o-gulehept-Culose
YH2OH HOYH HYOH HOYH
c=o
1
~-fhreeo-a//eNon-3-ulose
L-glUcO
-
HOYH HOYH CH2OH
~-erythro+-g/uco-Nond-ulose
not ~-threo-~-a//o-non-5-ulose
NOMENCLATURE OF CARBOHYDRATES
78
2-Curb-11. Diketoses
2-Carb-11.1. Systematic names The systematic name of a diketose is formed by replacing the terminal ‘-se’ of the stem name by ‘-diulose’.The locants of the (potential)carbonyl groups must be the lowest possible and appear before the ending. The stem name is preceded by the appropriate configurationalprefix. If there is a choice of names, a decision is made on the basis of 2-Carb-2.2.2. In cyclic forms,locants may be needed for the positions of ring closure; that of the (potential) carbonyl group is cited first. Examples:
CH,OH
c=o
CHpOH
c=o HYOH
H+OH HOYH
HOCH
HYOH
I
7=0
c=o
CHpOH
CHZOH
~-threeHexo-2,&diulose
mesexy/eHepto-2,6-diulose
2-Carb-11.2. Multiple sets of chiral centres If the carbonyl group(s) divides the sequence of chiral centres, the configurational prefixes are assigned in the normal manner (see 2-Carb-8.4) for all chiral centres; the non-chiral centres are ignored. Examples: YHzOH
c=o HOCH I
c=o I
HCOH I
CHzOH
D-threo-Hexo-2,4-diulose CHZOH
CHzOH
c=o
HYOH HOYH
c=o I c=o HOYH HOYH CHpOH
~-a/tro-Octo-4,5-diulose not ~-ta/o~cto-4,5-diulose
H$OH
c=o HO+H
} L-gl/cem -
CHPOH
~-g/ycero-o-manno-Nono-2,7-diulose
NOMENCLATURE OF CARBOHYDRATES
19
CH,OH HOCH
\
CH,OH
o-glycero~-id~-NonoB,Sdiulose 2-Carb-12. Ketoaldoses (aldoketoses,aldosuloses) 2-Carb-12.1.Systematic names Names of ketoaldoses are formed in the same way as those of diketoses, but with use of the termination ‘-ulose’ in place of the terminal ‘-e’ of the corresponding aldose name (2-Cub-8.2). The carbon atom of the (potential) aldehydic carbonyl group is numbered 1, and this locant is not cited in the name. The locant of the (potential) ketonic carbonyl group is given (as an infix before ‘dose’) unless it is 2; it may then be omitted (in this text, this locant is always retained for the sake of clarity). In cyclic forms, locants may be needed for the positions of ring closure; that of the (potential) carbonyl group is cited first. The position of the ring-size designator (e.g. pyrano) depends upon which carbonyl group is involved in ring formation (see examples). Examples:
I
MeOYH
YHO
HYOH
HOCH I
c=o
HOCH
H$OH HCOH CHiOH
~-arabin~-Hexos-3-ulose
Methyl ~-~-xy/uhexopyranosid-4-ulose
HYOH OH
H
CH20H
Methyl u-~-xy/~-Hexos-2-ulo-2,5-furanoside
NOMENCLATURE OF CARBOHYDRATES
80
2-Carb-12.2. ‘Dehydro’ names In a biochemical context, the naming of aldoketoses as ‘dehydro’ aldoses is widespread. Thus D-xylo-hexopyranos-4-ulose would be termed 4-dehydro-D-glucose. This usage of ‘dehydro’ can give rise to names which are stereochemically redundant, and should not be employed for naming derivatives. Note. In Enzyme Nomenclature [23] dehydro names are used in the context of enzymic
reactions. The substrate is regarded as the parent compound, but the name of the product is chosen according to the priority given in 2-Cub-2.2. Examples: D-Glucose + 0 2 = 2-dehydro-~-glucose+H202 (EC 1.1.3.10)
+ reduced acceptor Sucrose + acceptor= P-D-fructofuranosyl3-dehydro-a-~-allopyranoside (EC 1.1.99.13)
L-Sorbose + NADP’ = 5-dehydro-D-fructose + NADPH (reaction of sorbose dehydrogenase, EC 1.1.1.123)
2-Carb-I3. Deoxy sugars 2-Carb-13.1. Trivial names Several deoxy sugars have trivial names established by long usage, e.g. fucose (Fuc), quinovose (Qui) and rhamnose (Rha). They are illustrated here in the pyranose form. These names are retained for the unmodified sugars, but systematic names are usually preferred for the formation of names of derivatives, especially where deoxygenation is at a chiral centre of the parent sugar. (See also the alphabetical listing of trivial names in the Appendix.) Examples: H:#cH 3
OH
H
S OH
O
HO
‘OH
OH a-L- Fucopyranose
P-D-Quinovopyranose
6-Deoxy-a-~-galactopyranose
6-Deoxy-P-~-glucopyranose
HO HO *“ OH
OH
OH
L- Rhamnopyranose
2,6-Dideoxy-P-~-ribchhexopyranose
6-Deoxy-~-mannopyranose
(P-Digitoxopyranose)
NOMENCLATURE OF CARBOHYDRATES
81
HoboH OH OH
3,6-Dideoxy-~-o-xylehexopyranose
3,6-Dideoxy-P-o-arabinehexopyranose
(P-Abequopyranose)
(P-Tyvelopyranose)
Other trivial names that have been used include ascarylose for 3,6-dideoxy-~arabino-hexose, colitose for 3,6-dideoxy-~-xylo-hexose and paratose for 3,6-dideoxy-D-ribo-hexose. Note. Sugars with a terminal CH3 group should be named as w-deoxy sugars, as shown
above, not C-methyl derivatives.
2-Carb-13.2. Names derived from trivial names of sugars Use of ‘deoxy-’ in combination with an established trivial name (see Charts I and 11) is straightforward if the formal deoxygenation does not affect the configuration at any asymmetric centre. However if ‘deoxy’ removes a centre of chirality, the resulting names contain stereochemical redundancy. In such cases, systematic names are preferred, especially for the naming of derivatives. Note. The names 2-deoxyribose (for 2-deoxy-D-eryrhro-pentose)and 2-deoxyglucose (for 2-deoxy-~-arabino-hexose) are often used.
HO
H
2-Deoxy-~-erythro-pentofuranose 5-phosphate
2-Carb-13.3. Systematic names The systematic name consists of the prefix ‘deoxy-’, preceded by the locant and followed by the stem name with such configurational prefixes as necessary to describe the configuration(s) at the asymmetric centres present in the deoxy compound. Configurational prefixes are cited in order commencing at the end farthest from C-1. ‘Deoxy’ is regarded as a detachable prefix, i.e. it is placed in alphabetical order with any substituent prefixes. Note. The treatment of ‘anhydro’(see 2-Carb-26). ‘dehydro’(see 2-Carb-17.3) and ‘deoxy’ as detachable prefixes follows long-standing practice in carbohydrate chemistry, but is in conflict with [I41 (p. 12).
NOMENCLATURE OF CARBOHYDRATES
82
Examples: YHO HYH HYOH HFOH HYOH CH20H
4-Deoxy-~-~-xy/o-hexopyranose 2-Deoxy-o-nbc-hexose not 2-deoxy-o-allose not 4-deoxy-P-D-galactopyranose
:r)7H CHzOH
I ;;g
H$H
HY HFOH
7H3
c=o I
HYOH
-
HTH HYOH HYOH HYOH HOYH CHzOH
HO
OH
H
CHZOH
2-Deoxy-a-D-allc~heptopyranose l-Deoxy-L-glycerc~~-alirc~oct-2-ulose
Methyl 3-azido-4-O-benzoylB-bromo-2,3,6-trideoxy-2-fluoro-a-o-allopyranoside
If the CH2 group divides the chiral centres into two sets, it is ignored for the purpose of assigning a configurational prefix;the prefix(es) assigned should cover the entire sequence of chiral centres (see 2-Carb-8.4). Examples: YHO
HYOH TH2
HYOH HYOH CHpOH
3-Deoxy-~-ribo-hexose not 3-deoxy-o-erythrc~o-glycero-hexose
83
NOMENCLATURE OF CARBOHYDRATES YHpOH HOYH
c=o HCOH I
CH2 HYOH CHzOH
5-Deoxy-o-arabinehept-3-ulose not 5-deoxy-~-glycere~-glycere~-glycerehept-3-ulose
CHzOH
c=o I
HO7H HCOH I
HO$H YHZ HOS;H CHzOH
6-0eoxy-L-gluco-oct-2-ulose not 6-deoxy-~-glycero-~-xylo-oct-2-ulose
If the anomeric hydroxy group is replaced by a hydrogen atom, the compound is named as an anhydro alditol(2-Carb-26).
2-Carb-13.4. Deoxy alditols The name of an aldose derivative in which the aldehyde group has been replaced by a terminal CH3 group is derived from that of the appropriate alditol (see 2-Carb-19) by use of the prefix 'deoxy-'. Examples:
7H3 HO7H HCOH
' -
HYOH CHzOH
5
1-Deoxy-D-arabinitol not 5-deoxy-~-lyxitol
YHZOH HOYH HTH
CHpOH HOYH HYOH
HCOH
HYOH
CH3
CH3
1
-
YH3 HOYH HOYH HYOH
5
CHpOH
5-Deoxy-~-arabinitol not 1-deoxy-D-lyxitol
The alditols from fucose and rhamnose are frequently termed fucitol and rhamnitol (see 2-Carb-19.1).
NOMENCLATURE OF CARBOHYDRATES
84
2-Carb-14.Amino sugars 2-Carb-14.1. General principles The replacement of an alcoholic hydroxy group of a monosaccharide or monosaccharide derivativeby an amino group is envisaged as substitutionof the appropriate hydrogen atom of the corresponding deoxy monosaccharide by the amino group. The stereochemistry at the carbon atom carrying the amino group is expressed according to 2-Cub-8.2, with the amino group regarded as equivalent to OH. Some examples of N-substitutedderivatives are given here; for a detailed treatment see 2-Carb-25. 2-Carb-14.2. Trivial names Accepted trivial names are as follows. D-Galactosamine for 2-amino-2-deoxy-D-galactose D-Glucosamine for 2-amino-2-deoxy-D-glucose D-Mannosamine for 2-amino-2-deoxy-D-mannose D-Fucosamine for 2-amino-2,6-dideoxy-D-galactose D-Quinovosamine for 2-amino-2,6-dideoxy-D-glucose Neuraminic acid for 5-amino-3,5-dideoxy-D-glycero-D-gulucto-non-2ulosonic acid Muramic acid for 2-amino-3-O-[(R)-1-carboxyethyl]-2-deoxy-~-glucose. In the last two cases the trivial name refers specifically to the D enantiomer. (See also the alphabetical listing of trivial names in the Appendix.) and Such names as ‘bacillosamine’ for 2,4-diamino-2,4,6-trideoxy-~-glucose ‘garosamine’ for 3-deoxy-4-C-methyl-3-methylamino-~-arabinose are not recommended, as they imply replacement of OH by NH2 in a nonexistent parent sugar. Examples:
2-Amino-2-deoxy-D-glucopyranose(D-glucosamine).
NOMENCLATURE OF CARBOHYDRATES
85
5-Acetamido-3,5-dideoxy-~-glycer~~-~-ga/act~non-2-ulopy~anosonic acid (N-acetyl-a-neuraminicacid, cr-Neu5Ac), drawn in three ways (note that C-7 is the anomeric reference atom) ,-to
_ < I
2-Amino-3-0[( R)-1-carboxyethyl]-2-deoxy-~-~-glucopyranose (p-muramic acid)
For examples with nitrogen in the ring, see 2-Cab-34.1.
2-Carb-14.3. Systematic names The compounds are named by use of a combination of ‘deoxy-’ and ‘amino-’ prefixes. When the complete name of the derivative includes other prefixes, ‘deoxy-’ takes its place in the alphabetical order of detachable prefixes. Examples:
“I.
4,6-Dideoxy-4-formamido-2,3-di-Omethyl-~-mannopyranose -.
~...
2-Acetamido-l,3,4-tri-0acetyl-2,6-dideoxy-a-~-galactopyranose
86
NOMENCLATURE OF CARBOHYDRATES
When the amino group is at the anomeric position, the compound is normally named as a glycosylamine (see 2-Carb-33.6).
2-Carb-15. Thio sugars and other chalcogen analogues Replacement of a hydroxy oxygen atom of an aldose or ketose, or of the oxygen atom of the carbonyl group of the acyclic form of an aldose or ketose, by sulfur is indicated by placing the prefix ‘thio’, preceded by the appropriate locant, before the systematic or trivial name of the aldose or ketose. Replacement of the ring oxygen atom of the cyclic form of an aldose or ketose by sulfur is indicated in the same way, the number of the non-anomeric adjacent carbon atom of the ring being used as locant. Selenium and tellurium compounds are named likewise, by use of the prefix ‘seleno’ or ‘telluro’. Sulfoxides (or selenoxides or telluroxides) and sulfones (or selenones or tellurones) may be named by functional class nomenclature [ 131. Note. The appropriate prefix is thio, not thia; the latter is used in systematic organic chemical nomenclature to indicate replacement of CH2 by S.
Examples: CH~OACO SH
OAc
2,3,4,6-Tetra-Oacetyl- 1-thio-P-~-glucopyranose 5-Thio-P-D-glucopyranose
AcOCH HCO I
CH20Tr
Methyl 2,3,4-tri-Oacetyl-l-thio-6-Qtrityl-a-~-g1ucopyranoside
CHPOH H
OH
HOYH HCSe
HO “&&OH
OH
CH,OH
Methyl 4-seleno-a-o-xylofuranoside
4-Thio-P-o-galactopyranose
NOMENCLATURE OF CARBOHYDRATES
*+-
87
Ph
a-D-Glucopyranosyl phenyl (4-selenoxide
n
-$OMe YOMe
HOCH2
HO
HYOH HCSe
H
CHZOH
Methyl 5-seleno-a-D-fructofuranoside
kSEt
Ace, AcO
HqSEt
CH20Ac
A"O7H H F
I
OAc
d
HCS H+C CHZOAC
Ethyl 3,4,6,7-tetra-Oacetyl-Z-deoxy-l,5-dithio-a-~-g/uco-heptopyranoside Note. It is common practice in carbohydrate names to regard 'thio' as detachable. and therefore alphabetized with any other prefixes.
2-Carb-16. Other substituted monosaccharides 2-Carb-16.1. Replacement of hydrogen at a non-terminal carbon atom. The compound is named as a C-substituted monosaccharide. The group having priority according to the Sequence Rule ([13], Section E) is regarded as equivalent to OH for assignment of configuration. Any potential ambiguity (particularly when substitution is at the carbon atom where ring formation occurs) should be avoided by use of the R,S system to specify the modified stereocentre. Examples:
OH
2-GPhenyl-a-D-glucopyranose
NOMENCLATURE OF CARBOHYDRATES
88
AcNH
I
F
2- GAcetamido-2,3,4,6-tetra-Oacetyl-a-~-mannopyranosyl fluoride
OAc
(5R)-1,2,3,4-Tetra-Oacetyl-5-bromo-ol-~-~/cbhexopyranuronic acid or 1,2,3,4-tetra- Oacetyl-5-bromo-P-~-idopyranuronic acid
2-Carb-16.2. Replacement of OH at a non-terminal, non-anomericcarbon atom The compound is named as a substituted derivative of a deoxy sugar. The group replacing OH determines the configurational description. Any potential ambiguity should be dealt with by the alternative use of the R,S system to specify the modified stereocentre. Examples:
2-Deoxy-2-phenyl-a-~-glucopyranoseor 2-deoxy-2-Cphenyl-a-D-glucopyranose or (2R)-2-deoxy-2-phenyI-a-o-arabincbhexopyranose CH2Br
0
"'"T ON02
2,3-Diazido-4-Obenzoyl-6-bromo-2,3,6-trideoxy-a-~-mannopyranosyl nitrate Note. Use of the symbol C- is essential only in cases of potential ambiguity, to make clear that substitution is at carbon rather than at a heteroatom (cf. 2-Carb-18.2);however, it may also be used for emphasis.
2-Carb-16.3. Unequal substitution at a non-terminalcarbon atom The compound is named as a disubstituted deoxy sugar. Configuration is determined by regarding the substituent having priority according to the Sequence Rule ([13], Section E), as equivalent to OH. Any potential ambiguity should be dealt with by the alternative use of the R,S system to specify the modified stereocentre.
89
NOMENCLATURE OF CARBOHYDRATES
Example: CHpOH 0
HoxqL) OH
(2R)-2-BromoQ-chloro-2-deoxy-a-~-arabino-hexose of 2-bromo-2-chloro-2-deoxy-a-~-glucopyranose (Br has priority over CI)
2-Carb-16.4. Terminal substitution If substitution at the terminal carbon atom of the carbohydrate chain creates achiral centre, the stereochemistry is indicated by the R,S system. Example: YHO
HYOH HOFH
OH!;:: (54-5GCyclohexyl-5-Gphenyl-D-xylose
Note. A monosaccharide with a terminal methyl group is named as a deoxy sugar, not as a C-methyl derivative.
Substitution of aldehydic H by a ring or ring system is indicated simply with a C-substituent prefix. Examples: Ph I
5;=0
HCOH HO~H
HYOH
HoQoH
OH Ph
HCOH I
CHPOH
1-CPhenyl-D-glucose
1GPhenyl-0-D-glucopyranose
not 1Gphenyl-D-gluco-hex-1-ulose 2-Carb-16.5. Replacement of carbonyl oxygen by nitrogen (imines, oximes, hydrazones, osazones etc.)
The imino analogue of a monosaccharide may be named as an imino-substituted deoxy alditol.
NOMENCLATURE OF CARBOHYDRATES
90
Example: CH =NMe HYOH H T H HYOH CHpOH
1-Deoxy-1-(methylimino)-D-xylitol
Oximes, hydrazones and analogues are named directly as oxime or hydrazone derivatives etc. Example: CH=N-NHPh I
HYOH HOFH HCOH HYOH CHPOH
D-Glucose phenylhydrazone
The vicinal dihydrazones formed from monosaccharides with arylhydrazines have been called arylosazones, but are preferably named as ketoaldose bis(pheny1hydrazone)s Example:
CH =N-NHPh I
CH=N-NHPh I
HTH HYOH HYOH CHpOH
~-afabino-Hexos-2-ulosebis(pheny1hydrazone) or ~-afabino-hex-2-ulosephenylosazone
The triazoles formed on oxidising arylosazones (commonly called osotriazoles) may also be named as triazolylalditols.
HYOH HYOH CH20H
~-afabino-Hexos-Pulosephenylosotriazole or (1R)-l-(2-phenyl-2H-l,2,3-triazol-4-yl))-~-erythritol or 2-phenyl-4-(D-afabino-l,2,3,4-tetrahydroxybutyl)-2H-l,2,3-triazole
NOMENCLATURE OF CARBOHYDRATES
91
2-Carb-16.6. Isotopic substitution and isotopic labelling Rules for designating isotopic substitution and labelling are given in [ 131 (Section H). Parentheses indicate substitution; square brackets indicate labelling. The locant U indicates uniform labelling. Examples: ~ - (-'3C)Glucose 1 (substitution)
~-(2-*H)Mannose(substitution) ~-[U-'~C]Arabinose (labelling) 0-[l -3H]Galactose(labelling)
When isotopic substitution creates a centre of chirality, configuration is defined as for other types of substitution (see 2-Carb- 16.1 to 2-Carb-16.4). Example: YHO
H ~ H
HYH HYOH CH,OH
2-Deoxy-~-(2-*H)lyxose(substituted) of (2S)-2-deoxy-~-three(2-*H)pentose
2-Deoxy-2-['8F]fluoro-~-glucose (labelled) or (2R)-2-de0xy-2-['~F]fluoro-~-arabinc-hexose 2-Carb-I 7. Unsaturated monosaccharides*
2-Carb-17.1. General principles This section relates to the introduction of a double or triple bond between two contiguous carbon atoms of the backbone chain of a monosaccharide derivative. A double bond between a carbon atom of the backbone chain and an atom outside that chain, or a double or triple bond between two carbon atoms outside the backbone chain, will be treated according to the normal rules of organic nomenclature [ 13,141.
* This is based on the 1980 recommendations [S].Some examples have been omitted.
92
NOMENCLATURE OF CARBOHYDRATES
2-Carb-17.2. Double bonds Monosaccharide derivatives having a double bond between two contiguous carbon atoms of the backbone chain are named by inserting, into the name for the corresponding fully saturated derivative, the infix ‘x-en’. The infix is placed directly after the stem name that designates the chain length of the sugar. The locant x is the lower-numbered carbon atom involved in the double bond. Steric relations at a double bond are designated, if necessary, by the standard stereosymbols ‘(2)’ and preceding the whole name ([13], Section E). For multiple double bonds, infixes such as ‘x,y-dien’ are used (preceded by an inserted ‘a’ for euphony). I(&’
Note 1. The term ‘glycal’ is a non-preferred, trivial name for cyclic enol ether derivatives of sugars having a double bond between carbon atoms 1 and 2 of the ring. It should not be used or modified as a class name for monosaccharide derivatives having a double bond in any other position. Note 2. Following the principle of first naming the saturated derivative, compounds having a C=CR-0- group as part of a ring system are named as unsaturated derivatives of anhydro alditols if R is hydrogen or carbon; if R is a halogen, chalcogen, or nitrogen-family element, the resulting name is that of a glycenose or glycenosyl derivative. Note 3. The symbols (2)-and (0-may be omitted when the double bond is located within a ring system of six atoms or less, as steric constraints in such systems normally permit only one form. Examples: HO H Q H
H
H
1,5-Anhydro-2-deoxy-~-arabino-hex-l-enitol (non-preferred trivial name D-glUCal)
UO”
HOCH? 0 H
Methyl 2-deoxy-D-three pent-1-enofuranoside
1-(2-Deoxy-D-thre~pent-1-enofuranosyl)uracil
NOMENCLATURE OF CARBOHYDRATES
AcO
AcO
3,4-Di-OacetylQ-deoxy-D-erythropent-l-enopyranosylchloride
OH
H
2,6-Anhydro-1-deoxy-D-alfrehept-1-enitol (alphabetic preference over 2,6-anhydro-7-deoxy-~-fa/o-hept-6-enitol) fiH2
YH
HTH HYOH HYOH CH2OH
1,2-Dideoxy-~-arabinohex-l-enitol
H~OAC HYOAc CH~OAC
(Z)-1,2,3,4,5-Penta-Oacetyl-o-erytbrupent-l -enitol
7 AcO’C’Y’oAC HCOAc I
HCOAc CH~OAC
(E)-l,2,3,4,5-Penta- Oacetyl-D-erytbro-pent-1-enitol
93
94
NOMENCLATURE OF CARBOHYDRATES
MeO,
2
,OMe
FH
HOYH
HCOH CHzOH
2-Deoxy-D-threepent-1-enose dimethyl acetal VHpOH
Q "O H HO H
H
2,3-Dideoxy-a-~-erythrehex-2-enopyranose tH2
FH
HTH
2"
FH
HYOH HTOH CHpOH
1,2,4,5-Tetradeoxy-~-arabineocta1,4-dienitol CH2OH
HO
OH
1,5-Anhydr0-4-deoxy-~-erythrehex-4-enitol (enantiomeric precedence over 2,6-anhydr0-3-deoxy-~-efythrehexB-enitol)
Oe
HOH
HCHpOH
Methyl 3,4-dideoxy-~-~-glycerehex-3-en-2-ulopyranoside
o
H G
o
HH
2,3-Dideoxy-a-~-glycerc~hex-2-enopyranos-4-ulose
NOMENCLATURE OF CARBOHYDRATES
H
95
H
Methyl 3,4-dideoxy-~-~-glycefehept-3-en-2-ulopyranosid-5-ulose
H
O-CMe2
5,6-Dideoxy-l,2-Oisopropylidene-a-~-xy/o-hex-5-enof uranose 2-Carb-17.3. Triple bonds and cumulative double bonds Monosaccharide derivatives having a triple bond or cumulative double bonds in the backbone chain are named by the methods of 2-Carb-17.2, with the infix ‘n-yn’ for a triple bond and infixes such as ‘iJ-dien’ for cumulative double bonds. Note. This approach was not included in [S].
Alternatively they can be named on the basis of the corresponding fully saturated sugar by using the appropriate number of dehydro and deoxy prefixes (deoxy operations are regarded as formally preceding dehydro operations). The prefixes are placed in alphabetical order before the stem name. Examples:
CHZOH
H OH
(Z)-1,7-Anhydro-Z,5,6-trideoxy-D-%y/eoct-5-en-1 -ynitol or (z)-1,7-anhydro-lI 1,2,2-tetradehydro-2,5,6-trideoxy-~-xy/~oct-5-enitol
96
NOMENCLATURE OF CARBOHYDRATES OMe
A
111
C I
HO~H HYOH CH2OH
2-Deoxy-1-Omethyl-D-threepent-1 -ynitol or 1,1,2,2-tetradehydro-2-deoxy-1 t omethyl-D-threepentitot
6,7,8-Trideoxy-l,2:3,4-di-Qisopropylidene-a-~-galacteocta-6,7-dienopyranose or 6,7,7,8-tetradehydro-6,7,8-trideoxy-l,2:3,4-di-Oisopropylidenea-D-gaiacboctopyranose
c
111
C
O
H
H QOH H
OH
6-OAcetyl-5-deoxy-a-~-xylehex-5-ynofuranose or 6-Oacetyl-5,5,6,6-tetradehydro-5-deoxy-cr-~-xylehexofuranose y
3
$=O
c
111
C
O
H
Qo, H H
O-CMe2
5,6,8-Trideoxy-I ,2-Oisopropylidene-a-~-xyleoct-5-ynofuranos-7-ulose or 5,5,6,6-tetradehydro-5,6,8-trideoxy-l,2-Oisopropylidenea-~-xyieoctofuranos-7-ulose
NOMENCLATURE OF CARBOHYDRATES
97
2-Curb-18. Branched-chain sugars* 2-Carb-18.1. Trivial names Several branched monosaccharides have trivial names, some established by long usage. Examples are given below, together with systematic names for the (cyclic or acyclic) forms illustrated. (See also the alphabetical listing of trivial names in the Appendix.) Enantiomers of the sugars listed should be named systematically. Examples:
H
OH
OH
Hamamelose 2- C(Hydroxymethy1)-o-ribopyranose
Cladinose 2,6-Dideoxy-3-Gmethyl-3-O-methyl-~rib@hexopyranose
OH
OH
Streptose 5-Deoxy -3-Gf ormyl-~4yxofuranose
6-Deoxy-3-Cmethyl-D-mannopyranose (Evalose)
*
This is a modified form of the 1980recommendations [4]. Priority is now given to naming cyclic forms, since in most cases branched-chain monosaccharides will form cyclic hemiacetals or hemiketals.
98
NOMENCLATURE OF CARBOHYDRATES
2,3,6-Trideoxy-3- Cmethyl-4-Omethyl-3-nitro-~-arabino-hexopyranose (Evemitrose) MeNH Me% OH
3-Deoxy-4-Cmethyl-3-methylamino-~-arabinopyranose (Garosamine) YHO HCOH
I
HOCHZ-C-CH~OH I OH
D-Apiose (Api) 3-C(Hydroxymethy1)-D-glycero-tetrose Note. For the cyclic forms of apiose, systematic names are preferred, e.g.
HO
OH
3- C(Hydroxymethy1)-a-D-etythrofuranose [The name a-D-erythrczapiofuranose is ambiguous; Chemical Abstracts Service (CAS) uses the trivial name o-apio-a-D-furanose; Beilstein gives (34-a-o-apiofuranose]
2-Carb-18.2. Systematic names
A branched-chain monosaccharide is named as a substituted parent unbranched monosaccharide, as outlined in 2-Carb-16.1 to 2-Carb-16.4. Note. C-Locants are essential only where there is potential ambiguity,to make clear whether substitution is at carbon or at a heteroatom (cf. 2-Carb-16); however, they may also be used for emphasis. 2-Carb-18.3. Choice of parent
If the branched monosaccharide forms a cyclic hemiacetal or hemiketal, the chain which includes the ring atoms rather than any alternative open chain must be the basis of the name. Otherwise the parent is chosen according to the principles given in 2-Carb-2.1.
NOMENCLATURE OF CARBOHYDRATES
99
Examples (see also Chart V): YHO
YHO
HFOH
HCOH
HC , - CH
HOY-CHS HYOH
H+
HYOH
HYOH
CH20H
CHzOH
3-CMethyl-~-glucose (configuration determined by OH)
3-Deoxy-3-methyl-~-glucose (configurationdetermined by CH3)
I
CH3
2,3,6-T~deoxy-3-Gmethyl-4-Omethyl-3-nitro-~-lyxo-hexopyranose (nitrogen has priority over carbon for determiningconfiguration) CHO HCOH HYOH
(--J-;,y CH2OH
4-Cyclohexyl-4-deoxy-C(hydroxymethyl)-~-allose [oxygen (in CH20H) has priority over carbon (in cyclohexyl) at C-41 or (4R)-4-cyclohexyl-4-deoxy-4-(hydroxymethyl)-~-ribo-hexose
If the two substituents at the branch point are identical, so that this centre has become achiral, the stereochemistry is specified as described in 2-Carb-8.4. Examples:
tHO HCOH I
CH3CCH3 HYOH
HYOH CH2OH
3-Deoxy-3,3-dirnethyl-D-ribo-hexose
YHO HTOH HYOH HOCH2-C-CH20H
OH
4-C(Hydroxymethyl)-~-etythro-pentose
Note. Cyclizationof the second example between C- 1 and aCH2OH group would necessitate a three-centre configurational prefix for the ring form.
100
NOMENCLATURE OF CARBOHYDRATES
4
5
6
1 3-Deoxy-3-[(1R,2S)-1,2-dihydroxy-3-oxopropyl]-~-g~ycero-D-a~tro-heptopyranose or 3-deoxy-3-(D-threo- 1,2-dihydroxy-3-oxopropyl)-~-glycero-D-altroheptopyranose (not the alternative open-chain six-carbon dialdose or eight-carbon aldose, cf. 2) 2 4-Deoxy-4-(~-ribo-1,2,3,4-tetrahydroxybuty1)-D-afrro-hexodialdose
3 4-Deoxy-4-[ (1R,2R)- 1,2-dihydroxy-3-oxopropyl]-~-a~fo-heptulo-2,S-fur~ose or 4-deoxy-4-(D-erylhro- 1,2-dihydroxy-3-oxopropyl)-~-aZ~o-heptulo-2,S-furanose
(not the alternative ketoaldose, cf. 4) 4 4-Deoxy-4-[(1R,2S)-1,2,3-trihydroxypropyl]-~-talo-heptos-6-ulose or 4-deoxy-4-(~-erythro-I ,2,3-trihydroxypropyI)-~-talo-heptos-6-ulose 5 4,6-Dideoxy-3-C-(~-g~yceycero-1-hydroxyethyl)-~-ribo-hexose (not the alternative pentose) 6 3,4-Dideoxy-3-[3-hydroxy-2-(hydroxymethyl)propyI]-4-C-methyl-~-mannose (not the alternative threo-hexose)
Chart V. Choice of parent in branched-chain monosaccharides. In the first names given for examples 1,3and 4, side-chain configuration is specified by use of R and S. This approach is generally preferred in all but the simplest cases, as less open to misinterpretation.
NOMENCLATURE OF CARBOHYDRATES
101
Note. These recommendations may give rise to very different names for cyclic and acyclic forms of the same basic structures, resulting from different priorities. Thus, in Chart V, structures 1 and 2 are virtually identical, differing only by cyclization. The same holds for structures 3 and 4.
2-Carb-18.4. Naming the branches Each branch will be named as an alkyl or substituted alkyl group replacing a hydrogen atom at the branch point of the parent chain. Within the branches, configurations around asymmetric centres can either be indicated using the R,Ssystem or, if they are carbohydrate-like and assignment is straightforward, by the use of the configurational prefix. For this purpose, and in the absence of a carbonyl group (or a terminal COOH or its equivalent) in the branch, the point of attachment of the branch (on the main chain) is regarded as equivalent to an aldehyde group.
Example:
I
HTH HYOH HTH HOCH CH,OH
L-glucel,2,3,4,5-Pentahydroxypentyl If there is a carbonyl group in the branch (or a terminal COOH or its equivalent), its position (assigned lowest number when stereochemistry is being considered) is used to define the configurational prefix (see examples 1 and 3 in Chart V). Use of the R,S system is generally preferred, as less open to misinterpretation.
For an alternative approach to naming carbohydrate residues as substituents see for the 2-Carb-31.2 [which would give the name (1R)- or (1s)-L-arabinitol-l-C-yl above example, depending on the ligands at the branch point]. 2-Carb-18.5. Numbering The carbon atoms of the parent chain are numbered according to 2-Carb-2.2.1. If a unique numbering is required for the branch(es) (e.g. for X-ray or Nh4R work), the carbon atoms may be given the locant of the appropriate branch point, with the internal branch locant as superscript, e.g. 42 for position 2 of the branch at position 4 of the main chain. This style of branch numbering is not to be used for naming purposes: e.g. the side-chain-methylated derivative of compound 5 is named 4,6-dideoxy-3-C-[(R)- 1-methoxyethyl]-D-ribo-hexose, and not as a 3 1-@methyl derivative.
2-Carb-18.6. Terminal substitution See 2-Carb- 16.4.
NOMENCLATURE OF CARBOHYDRATES
102
2-Carb-19. Alditols
2-Carb-19.1. Naming Alditols are named by changing the suffix ‘-0se’ in the name of the corresponding aldose into ‘401’. If the same alditol can be derived from either of two different aldoses, or from an aldose or a ketose, preference is ruled by 2-Carb-2.1 or 2.2.2 as appropriate. Examples: CHZOH HOYH
YHpOH
HFOH
HYOH
HCOH
HOYH
I
HOFH
HOYH HYOH
HYOH
HCOH
HYOH
I
CH20H
CH2OH
D-erythfol-galacto~ctitol
D-glyceroQ-ga/acfu-Heptitot not L-glycef~D-manno-heptitol
not o-fhrec~-guboctitoI
CH20H I
HCOH
CHpOH
I
I
H
HTH
~
HFOH
HYOH
HYOH
HYOH
H
CHZOH
CHpOH
D-Arabinitol (Ara-ol) not D-lyxitol
D-Glucitol (Glc-01) not L-gulitol (the trivial name sorbitol is not recommended)
The trivial names fucitol and rhamnitol are allowed for the alditols corresponding to the 6-deoxy sugars fucose and rhamnose. YHpOH HOYH HYOH HYOH HOYH CH3
L-Fucitol (L-FUC-01)or 1-deoxy-o-galactitol not 6-deoxy-~-galactitol(cf. 2-Carb-2.2.3.1)
NOMENCLATURE OF CARBOHYDRATES
I03
CH2OH HYOH HYOH HOqH HOYH CH3
L-Rhamnitol (L-Rha-ol) or 1-deoxy-L-mannitol
2-Carb-19.2. meso Forms Alditols that are symmetric and therefore optically inactive - the meso forms - can be designated by the prefix meso-. Examples: meseErythritol meso-Ribitol meseGalactitol
The prefix D or L must be given when a derivative of a meso form has become asymmetric by substitution. It is also necessary to define the configurational prefixes as D or L in the case where there are more than four contiguous asymmetric carbon atoms. Examples: CHzOH
I
H+OH
YHzOH
HTH
HYOH
HYOH
HTH
HTH
HOYH HCOMe
HYOH CHzOH
7
meseo-glyceral-ideHeptitoI not L-glycereo-ideheptitol; cf. 2-Garb-2.2.3
CHzOH
5-0-Methyl-o-galactitol not 2-O-methyl-~-galactitol
2-Curb-20.Aldonic acids 2-Carb-20.1. Naming Aldonic acids are divided into aldotrionic acid, aldotetronic acids, aldopentonic acids, aldohexonic acids, etc., according to the number of carbon atoms in the chain. The names of individual compounds of this type are formed by replacing the ending ‘-ose’ of the systematic or trivial name of the aldose by ‘-onic acid’.
NOMENCLATURE OF CARBOHYDRATES
104
Examples: YOOH
YOOH
700-
HYOH
HCNHp
HYOH
HTH
H T H
HYH
HYOH
HYOH
HYOH
HYOH
HYOH
HFOH
CHpOH
CHpOH
CH20H
D-Gluconic acid
D-Gluconate
2-Amino-2-deoxy-~-gluconic acid
2-Carb-20.2. Derivatives Salts are named by changing the ending ‘-onic acid’ to ‘-onate’, denoting the anion. If the counter ion is known, it is given before the aldonate name. Example: Sodium D-gluconate Esters derived from the acid function are also named using the ending ‘-onate’. The name of the alkyl (aryl, etc.) group is given before the aldonate name. Alternative periphrase names like ‘aldonic acid alkyl (aryl, etc.) ester’ may be suitable for an index.
Amides are designated by the ending ‘-onamide’, and nitriles by the ending ‘-ononitrile’. Examples: /
YOOMe HYOH HOYH
Me
?OOC\H HCOH Me HY-OMe
HYOH HYOH
MeO-CH HOYH
CHPOH
CHpOH
Methyl o-gluconate
lsopropyl3,4-di-Omethyl-~-mannonate
CONME* HOYH HYOH HOYH CHpOH
N,N-Dimethyl-L-xylonarnide
YOOMe HOYH ( 7 2
HYOH CHzOH
Methyl 3-deoxy-D-threepentonate
NOMENCLATURE OF CARBOHYDRATES
105
COOMe HYOAc AcOCH AcOCH CH~OAC
Methyl tetra-Oacetyl-L-arabinonate
Lactones are named with the ending ‘-onolactone’. The locants must be given (in the form ‘-ono-i,j-lactone): that of the carbonyl group (i) is cited first, and that of the oxygen (j]second (see examples below). Penphrase names (see alternatives in parentheses) appear widely in the literature but are not recommended. Lactam are named similarly by use of the ending ‘-onolactam’. Examples: CH20H
o&?&&H
H H
OH
D-Glucono-l,44actone (D-Gluconic acid y-lactone)
3-Deoxy-~-ribcbhexono-1 ,&lactone
D-GlUCOnO-1,&lactone (0-Gluconic acid &lactone)
5-Amino-5-deoxy-~-mannono-l,5-lactam
Acyl halides are named by changing the ending ‘-onic acid’ to ‘-onoyl halide’ Example: YOCl HfOAc AdYH HCOAc HCOAc CH,OAc
Penta-Oacetyl-o-gluconoyl chloride
NOMENCLATURE OF CARBOHYDRATES
106
More complicated examples of general principles for naming acid derivatives can be found elsewhere [ 13,141.
2-Carb-21.Ketoaldonic acids
2-Carb-21.1. Naming Names of individual ketoaldonic acids are formed by replacing the ending ‘-dose’ of the corresponding ketose by ‘-ulosonic acid’, preceded by the locant of the ketonic carbonyl group. The anion takes the ending ‘-ulosonate’. The numbering starts at the carboxy group. In glycosides derived from ketoaldonic acids, the ending is ‘-ulosidonic acid’, with appropriate ring-size infix, e.g. ‘-ulopyranosidonic acid’. Examples: YOOH HTH HCOH HCOH
7OOH
c=o I HYOH HYOH CHpOH
I
c=o CH20H
~-erythrePent-2-ulosonicacid
D-afabineHex-5-ulosonicacid
n
H
HYOH
HO
HO
H
a-o-afabineHex-2-ulopyranosonicacid CHzOH I HOCH
H H
H
3-Deoxy-a-D-manneoct-2-ulopyranosonicacid
Note. The last of the above examples is one of the possible forms of the compound referred to by the three-letter symbol Kdo (formerly the abbreviation KDO, from the previously allowed trivial name ketodeoxyoctonic acid). Similarly the symbol Kdn for the C9 sugar 3-deoxy-D-g~ycero-D-galacio-non-~-u~opyranosonic acid is widely used.
NOMENCLATURE OF CARBOHYDRATES
107
2-Carb-21.2. Derivatives Esters, lactones, lactams, acyl halides etc. are named by modifying the ending '-ic acid' as described for aldonic acids (2-Carb-20.2). Examples:
0
HO
r-
EtOOC-COMe I
t40Cjt-i
-
HCOH I
HCOH
OMe
HO
I
H
CHPO-
Ethyl (methyl a-~-arabino-hex-2-ulopyranosid)onate
Note. The parentheses are inserted to distinguish between the ester alkyl group (cited first) and the glycosidic 0-alkyl group.
H
&-&+
OH
E
HCO-
c=o
0
H
Hceo Indol-3-yl D-xy/ehex-5-ulofuranosonate; trivial name isatan B
-
CHzOH
I
-
CH,OH HI I
H
D
o
-
-
CH20H H1 I
2 0
_ .
H
o
HO
~-xy/eHexP-ulosono-l,4-lactone
OH
OH
L-/yxeHex-2-ulosono-l,6lactone
L-tbrec-Hex-2-enono-1,.l-lactone (L-Ascorbic acid is the equilibrium mixture of all three isomers)
NOMENCLATURE OF CARBOHYDRATES
108
2-Carb-22.(Ironic acids 2-Carb-22.1. Naming and numbering The names of the individual compounds of this type are formed by replacing (a) the ‘-ose’ of the systematic or trivial name of the aldose by ‘-uronic acid’, (b) the ‘-oside’ of the name of the glycoside by ’-osiduronic acid’ or (c) the ‘-osyl’ of the name of the glycosyl group by ‘-osyluronicacid’. The carbon atom of the (potential) aldehydic carbonyl group (not that of the carboxy group as in normal systematic nomenclature [ 13,141)is numbered 1 (see 2-Carb-2.1, note 1). 2-Carb-22.2. Derivatives Derivatives of these acids formed by change in the carboxy group (salts, esters, lactones, acyl halides, amides, nitriles, etc.) are named according to 2-Carb-20.2. The anion takes the ending ‘wonate’. Esters are also named using the ending ‘-uronate’. Examples: YHO HYOH HOYH
Ho=4
HYOH
HTOH
COOH
D-Glucuronic acid
Phenyl P-D-glucopyranosiduronic acid not phenyl P-D-glucuronosideor phenyl glucuronide H
H
OH
Methyl a-L-idopyranosiduronicacid
Br
Methyl 2,3,4-tri-Oacetyl-a-D-glucopyranosyluronatebromide
Hm
109
NOMENCLATURE OF CARBOHYDRATES
HOCH
I
OH
H
CN
Methyl a-L-glucofuranosidurononitrile
COONa
Sodium (methyl a-L-g1ucofuranosid)uronate COOEt
YHO HFOH
H
H
HYOBz
COOEI
Ethyl 2,3,5-~ri-~benzoyl-a-~-rnannofuranuronate ~-Glucurono-6,3-lactone
o=c
o=c
H
OH
H
OH
~-GIucofuranurono-6,3-lactone Methyl a-~-glucofuranosidurono-6,3-lactone COOH
H
OH
4-Deoxy-~-threo-hex-4-enopyranuronic acid C?OMe
H
OH
Methyl 4-deoxy-~-thre@hex-4-enopyranuronate
NOMENCLATURE OF CARBOHYDRATES
110
COOH
H
OH
0
Methyl 4-deoxy-a-~-threehex-4-enopyranosiduronic acid COOMe
OH
H OPh
H
OH
Methyl (phenyl4-deoxy-~-~-threehex-4-enopyranosid)uronate HO
CONH2
HO-0Me OH
Methyl P-D-galactopyranosiduronarnide
2-Carb-23. Alduric acids
2-Carb-23.1. Naming Names of individual aldaric acids are formed by replacing the ending ‘-ose’ of the systematic or trivial name of the parent aldose by ‘-ark acid’. Choice between possible names is based on 2-Carb-2.2.2. Examples: YOOH fOOH HCOH HTH
YOOH HYOH HTH HYOH
HTH HOYH COOH
L-Altraric acid not L-talaric acid
HYOH COOH
o-Glucaricacid not L-gularic acid
YOOH
HYOH H T H H T H HYOH HOCH I
COOH
HfOH
-
H T H HfOH HCOH HOYH COOH
L-glycereD-galacto-Heptaricacid not L-glycereD-gluco-heptaricacid
2-Carb-23.2. meso Forms To the names of aldaric acids that are symmetrical, which therefore have no D- or L- prefix, the prefix ‘meso-’ may be added for the sake of clarity. Examples: meso-erythraric acid, meso-ribaric acid, meso-xylaric acid, meso-allaric acid, mesogalactaric acid.
NOMENCLATURE OF CARBOHYDRATES
111
The D or L prefix must however be used when a meso-aldaric acid has become asymmetric as a result of substitution. Examples: COOH
COOH I
I
YOOH
HYOH
HYOH
HYOH HTH HYOH
HOYH
HOCH
HOYH
M~O-CH HYOH
HCOH I
COOH
COOH
COOH
meso-Xylaric acid
meso-Galactaric acid 4-OMethyl-~-galactaricacid not 3-Crrnethyl-~-galactaricacid
2-Carb-23.3. Trivial names
For the tetraric acids, the trivial name tartaric acid remains in use, with the stereochemistry given using the R,S system. Esters are referred to as ‘tartrates’ (the second ‘a’ is elided). Examples: YOOH
YOOH
HYOH
H T H
HYOH
HOYH COOH
COOH
(2R,3R)- or (+)-Tartaric acid or L-threaric acid
(2S,3S)-or (-)-Tartaric acid or o-threaric acid
YOOH HYOH HYOH COOH
(2R,3S)- or meso-Tartaric acid
or erythraric acid Note. In the older literature, there is confusion about the use of D and L in the case of tartaric acids. It is therefore recommended to use the R,S system in this case.
2-Carb-23.4. Derivatives Derivatives formed by modifying the carboxy group (salts, esters, lactones, lactams, acyl halides, amides, nitriles etc.) are named by the methods of 2-Carb-20.2. Dilactones, half-esters, amic acids etc. are named by the methods of [13, 141. In cases of ambiguity, locants should be specified.
NOMENCLATURE OF CARBOHYDRATES
112
Examples: YOOMe
YOOH
HCOH
HYOH
I
HO7H
HTH
HTH
HYH
HYOH
HCOH I
COOH
COOMe
1-Methyl hydrogen D-galactarate YONH?
6-Methyl hydrogen o-galactarate FOOMe
HYOH
HYOH
HYH
HO$H
HYOH
HYOH
HYOH
HYOH
COOH
HO : $H
CONH,
D-Glucar-1-amic acid
0
Methyl D-glucar-6-amate L-Mannaro-l,4:6,3-dilactone
2-Carb-24. O-Substitution 2-Carb-24.1. Acyl (alkyl) names Substituents replacing the hydrogen atom of an alcoholic hydroxy group of a saccharide or saccharide derivative are denoted as O-substituents. The '0-' locant is not repeated for multiple replacements by the same atom or group. Number locants are used as necessary to specify the positions of substituents; they are not required for compounds fully substituted by identical groups. Alternative periphrase names for esters, ethers, etc. may be useful for indexing purposes. For cyclic acetals see 2-Carb-28. Examples: HC-0 I
H$OAc AcO$H HFOAc HYOAc
OH
CH20Ac
Penta-Oacetyl-aldehydcm-glucose 2,4-Di-Oacetyl-6-Otrityl-~-glucopyranose or aldehydeo-glucose pentaacetate
Ho
CH20Ms
HO%OH
6- OMethanesulfonyl-o-galactopyranose or o-galactopyranose 6-methanesulfonate
113
NOMENCLATURE OF CARBOHYDRATES
Tetra-Obenzoyl-a-D-glucopyranosylbromide
HO OH
4,6-Di-CTmethyl-a-o-galactopyranose
Note. Acyl substituents on anomeric OH are designated (as above) by 0-acyl prefixes. However, anomeric 0-alkyl derivatives are named as glycosides (see 2-Carb-33).
2-Carb-24.2. Phosphorus oxoacid esters 24.2.1. Phosphates Of special biochemical importance are the esters of monosaccharides with phosphoric acid. They are generally termed phosphates (e.g. glucose 6-phosphate). In biochemical use, the term ‘phosphate’ indicates the phosphate residue regardless of the state of ionization or the counter ions. The prefix terms used for phosphate esters in organic nomenclature ([ 141, p.65) are ‘0-phosphono-’ and ‘0-phosphonato-’ for the groups (HOhP(0)- and (032P(O)respectively, bonded to oxygen. The term ‘phospho-’ is used for (H0)2P(O)- or ionized forms in a biochemical context (see recommendations for the nomenclature of phosphorus-containing compounds [241).
If a sugar is esterified with two or more phosphate groups, the compound is termed bisphosphate, trisphosphate etc. (e.g. fructofuranose 1,6-bisphosphate). The term diphosphate denotes an ester with diphosphoric acid, e.g. adenosine 5‘-diphosphate. Note. In abbreviations, a capital P is used to indicate a terminal -P03H2 group or a non-terminal -POzH- group (or dehydronated forms).
Examples: CH20P03H*
HO
Ho* OH OH D-GlUcOpyranOSe 6-(dihydrogen phosphate) or 6-Ophosphono-o-glucopyranose
CHZOH
Ho% HO OH0po:-
a-D-Glucopyranosylphosphate (biochemical usage: glucose 1phosphate) (Glcl P)
114
NOMENCLATURE OF CARBOHYDRATES CH20P0:-
H H o * HO o-Glucopyranose 6-phosphate (often shortened to glucose 6-phosphate) or 6-Ophosphonato-~-glucopyranose or 6-phospho-o-glucose (GlcGP) (in a biochemical context) 0po:-
OH
H
o-Fructofuranose 1,Sbisphosphate (often shortened to fructose 1,&bisphosphate) or 1,6-di-Ophosphonato-o-fructofuranose or 1,&bisphospho-o-fructofuranose O+yop0,2HCOH H,&OPO:-
3-OPhosphonato-D-glyceroylphosphate or 3-phospho-o-glyceroylphosphate or 1,3-bisphospho-o-gIycerate(for biochemical usage) COOH "OH%
OP03H,
a-o-Glucopyranuronic acid 1-(dihydrogen phosphate) (biochemical usage: glucuronate 1-phosphate) (GlcA1 P)
HO
bH
Adenosine 5'-diphosphate (ADP) or 5'-diphosphoadenosine
NOMENCLATURE OF CARBOHYDRATES 6
115
0 II
CH,OH
HO OH Uridine 5’-(a-D-gluCOpyranosyldiphosphate) (trivial name uridinediphosphoglucose) (UDP-Glc)
0
COOH
HO
Cytidine 5’-(5-acetamido-3,5-dideoxy-~-glycer~~-~-ga/acfonon-2-ulopyranosylonicacid monophosphate) (CMP-P-Neu5Ac)
24.2.2. Phosphonates The following examples illustrate the use of phosphonate terminology for esters of phosphonic acid, HP(O)(OH)z. For formation of the alternative (substitutive) names, see 2-Carb-31.2. 0
Examples:
H oII - T - m w H M e H
H HO
OH
Methyl P-o-ribofuranoside5-(hydrogen phosphonate) or methyl 5-deoxy-P-~-ribofuranosid-5-yl hydrogen phosphonate U
HOCHp
OH
H
il N3
H
3’-Azido-3’-deoxythymidine 5’-[(methyl 5-acetamido-3,5-dideoxyphosphonate] ~-g/ycerc~a-~-ga/acto-non-2-ulopyranosylonate)
116
NOMENCLATURE OF CARBOHYDRATES
Derivatives substituted on phosphorus are named by standard procedures [ 13, 141; e.g. P-methyl derivatives are named as methylphosphonates. Compounds with a phosphonate group linked by a P-C bond to a carbohydrate residue may be named as glycos-n-ylphosphonates(cf. 2-Carb-3 1.2) or as C-substituted carbohydrates (cf. amino sugars, 2-Carb-14). Example:
CH20H
H oH -o OP(0Me)Z
2-Deoxy-2-dimethoxyphosphoryl-~-glucopyranose (this usage of ‘phosphoryl’ is given in [13],Section D, Rule 5.68, and [14], p. 65) or dimethyl 2-deoxy-~-glucopyranos-2-ylphosphonate
24.2.3. Phosphinutes Esters of phosphinic acid, HzP(O)(OH), are named by the same methods as used for phosphonates. For examples with two P-C bonds see 2-Cub-3 1.3.
2-Carb-24.3. Sulfates The prefix terms used for sulfuric esters are ‘0-sulfo-’ and ‘0-sulfonato-’, for the groups (HO)S(0)2- and (O-)S(O)z- respectively, bonded to oxygen. Sulfates may also be named by citing the word ‘sulfate’,preceded by the appropriate locant, after the carbohydrate name.
Example: HO
HO
I
OH
so, a-D-Galactopyranose 2-sulfate
or 2-Osulfonato-a-~-galactopyranose The mixed sulfuric phosphoric anhydride (PAdoPS or PAPS) of 3’-phospho-5’adenylic acid is named as an acyl sulfate:
NOMENCLATURE OF CARBOHYDRATES
I17
I
0-
3'-Phospho-5'-adenylyl sulfate (PAPS)
2-Carb-25. N-Substitution Substitution, e.g. acylation, at the NH2 group of an amino sugar can be dealt with in two different ways: (a) The whole substituted amino group can be designated as a prefix, e.g. 2-acetamido- (or 2- butylamino-) 2-deoxy-D-glucose. For the purpose of the configurational prefix, the group is considered to take the place of the former OH group.
(b) If the amino sugar has a trivial name, the substitution is indicated by a prefix preceded by an italic capital N. Note. In carbohydrate nomenclature, substitution at a heteroatom is normally indicated by
citing the locant of the attached carbon atom, followed by a hyphen, and then the italicized heteroatom element symbol, e.g. 2-@methyl, 5-N-acetyl. Substituentson the same kind of heteroatom are grouped (e.g. 2,3,4-tri-O-methyl),and substituentsof the same kind are cited in alphabetical order of heteroatoms (e.g. 5-N-acetyl-4.8.9-tri-O-acetyl).The alternative format with superscript numerical locanrs (e.g. N 5 ,O4,O8,O9-tetraacetyl),used in some other areas of natural product chemistry, is unusual in carbohydrate names. Examples: CHzOAC I
HCN(Me)Ac I
AcTH HCOAc HYOAc CH,OAc
1,3,4,5,6-Penta-OacetyI-2-deoxy-2-( Krnethy1acetarnido)-o-glucitol OH CHzOH
H
o
b
o
"
2-Acetarnido-2-deoxy-~-galactopyranose or Kacetyl-o-galactosamine
NOMENCLATURE OF CARBOHYDRATES
118
KGlycoloyl-a-neuraminic acid (a-Neu5Gc) (D is implied in the trivial name)
5-N-Acetyl-4,8,9-tri-O-acetyl-a-neuraminic acid (a-Neu4,5,8,9Ac4)
2-Carb-26. Intramolecular anhydrides An intramolecular ether (commonly called an intramolecular anhydride), formally arising by elimination of water from two hydroxy groups of a single molecule of a monosaccharide (aldose or ketose) or monosaccharide derivative, is named by attaching the (detachable) prefix ‘anhydro-’ preceded by a pair of locants identifying the two hydroxy groups involved. Note. Detachable prefixes are cited in alphabetical order along with any substituent prefixes.
Examples:
NOMENCLATURE OF CARBOHYDRATES
H
119
OMe
Methyl 3,6-anhydro-2,5-di-Omethyl-~-~-glucofuranoside
)
“!$$ CH20H
C02H
OH
5-Acetamido-2,6-anhydro-3,5-dideoxy-o-glycerc~~-galacto-non-2-enonic acid (Neu2enSAc)
The compounds usually known as monosaccharide anhydrides or glycose anhydrides (earlier ‘glycosans’), formation of which involves the anomeric hydroxy group, are named by the same procedure. In these cases the order of preference of ring size designators is pyranose > furanose > septanose. However, three- or four-membered rings should normally be cited as ‘anhydro’ if there is a choice. Trivial names for anhydro monosaccharides,though established by usage, are not recommended because of possible confusion with polysaccharide names based on the use of the termination ‘-an’.
p
Examples:
7
0
CH2OH
OH OH
OH
1,6-Anhydro-~-o-glucopyranose 2,7-Anhydro-~-o-altrc~heptQ-ulopyranose not 1,5-anhydro-a-~-gIucoseptanose (older trivial name: sedoheptuiosan) (older trivial name: levoglucosan) CHzOAC
3,4,6-Tri-Oacetyl-l,2-anhydro-a-o-glucopyranose not 3,4,6-tri-Oacetyl-l,5-anhydro-~-~-glucooxirose
120
NOMENCLATURE OF CARBOHYDRATES
OH
qo 0
1,6-Anhydro-3,4-dideoxy-~-~-glycero-hex-3-enopyranos-2-ulose (trivial name: levoglucosenone)
2-Carb-27. Intermolecularanhydrides The cyclic product of condensation of two monosaccharide molecules with the elimination of two molecules of water (commonly called an intermolecular anhydride), is named by placing the word ‘dianhydride’after the names of the two parent monosaccharides. When the two parent monosaccharides are different, the one preferred according to the order of preference given in 2-Carb-2.1 is cited first. The position of each anhydride link is indicated by a pair of locants showing the positions of the two hydroxy groups involved; the locants relating to one monosaccharide (in a mixed dianhydride, the second monosaccharide named) are primed. Both pairs of locants immediately precede the word ‘dianhydride’. Examples: OH
OH
H
H
a-D-Fructopyranose P-D-fructopyranose 1 , 2 l’,Bdianhydride H
HO
H
H
h
OH
a-D-Fructopyranose a-D-sorbopyranose 1,2’:1 ‘,Pdianhydride
NOMENCLATURE OF CARBOHYDRATES
121
(a-D-Galactopyranuronic acid) P-L-rhamnopyranose 1,2': 1',Bdianhydride
2-Carb-28. Cyclic metals Cyclic acetals formed by the reaction of saccharides or saccharidederivatives with aldehydes or ketones are named in accordance with 2-Carb-24.1, bivalent substituent names (formed by general organic nomenclature principles) being used as prefixes. In indicating more than one cyclic acetal grouping of the same kind, the appropriatepairs of locants are separated typographically when the exact placement of the acetal groups is known. Examples:
Me&,
.OCH*
I
OqH HO$H
HYOH
HCO.
I ,CMe2 H2CO
Methyl (R)-4,6-~benzylidene-a-o-glucopyranoside
NOMENCLATURE OF CARBOHYDRATES
122
Methyl (S)-2,3:(R)-4,6-di-Obenzylidene-a-o-allopyranoside
3,4,6-Tri-Obenzoyl-[( S)-1,2-Ochloro(methoxy)methylene]-~-o-mannopyranose
\C /
phT%
OMe
I
Ph
3,4,6-Tri- 0-acetyl-a-o-glucopyranose(R)-l,2-(methyl orthoacetate) or 3,4,6-tri-Oacetyl-[(R)-l,2-0( 1-rnethoxyethylidene)]-a-D-glucopyranose Note 1. The last two examples contain cyclic ortho ester structures. These compounds are
conveniently named as cyclic acetals. Note 2. In the last four examples, new asymmetric centres have been introduced at the carbonyl carbon atom of the aldehyde or ketone that has reacted with the saccharide. When known, the stereochemistry at such a new centre is indicated by use of the appropriate R or S symbol ([13], Section E) placed in parentheses, immediately before the locants of the relevant prefix.
2-Carb-29. Hemiucetals, hemiketak and their thio analogues The compounds obtained by transforming the carbonyl group of the acyclic form of a saccharide, or saccharide derivative, into the grouping:
’
‘OH
,
’
‘SH
SR
,
Or
’
‘SH
(R = alkyl or at-yl) are named as indicated in 2-Carb-30, by using the terms ‘hemiacetal’, ‘monothiohemiacetal’, or ‘dithiohemiacetal’(or the corresponding ‘hemiketal’ terms for ketone derivatives), as appropriate. The two isomers of a monothiohemiacetal are differentiated by use of 0 and S prefixes.
NOMENCLATURE OF CARBOHYDRATES
123
Examples: ?Et
HCOH
HCOBz BzOCH I
HCOBz HFOBz CH~OBZ
(1S)-2,3,4,5,6-Penta-0benzoyl-~-glucoseethyl hemiacetal SEt HYSH HCOBz
BzTH HCOBz
HCOBZ CH~OBZ
(1 5)-2,3,4,5,6-Penta-Obenzoyl-o-glucose ethyl dithiohemiacetal ?Et
H$SH HCOBz I
BzOCH HCOBz HCOBz CH~OBZ
(1R)-2,3,4,5,6-Penta-ObenzoyI-o-gtucose O-ethyl monothiohemiacetal SEt
HtOH HCOBz I
BzO$H HCOBz HCOBz CH208z
(1 S)-2,3,4,5,6-Penta-Obenzoyl-o-glucoseS-ethyl monothiohemiacetal
Note. In these compounds carbon atom number 1 has become chiral. When known, the stereochemistryat this new chiral centre is indicated using the R,S system ([ 131, Section E).
2-Carb-30. Acetals, ketals and their thio analogues The compounds obtained by transforming the carbonyl group of a saccharide or saccharide derivative into the grouping:
NOMENCLATURE OF CARBOHYDRATES
124
are named by placing after the name of the saccharide or saccharide derivative the term ‘acetal’, ‘monothioacetal’or ‘dithioacetal’(or the corresponding ‘ketal’ terms for ketone derivatives) as appropriate, preceded by the names of the groups R’ and R2. With monothioacetals, the mode of bonding of two different groups R’ and R2 is indicated by the use of the prefixes 0 and S. Examples: HC(OE1)z
YHzOH
Y(OE02
HCOH I
HOYH
HOYH
HYOH
HYOH
HYOH
HYOH
CHZOH
CHZOH
D-Glucose diethyl acetal
D-Fructose diethyl ketal
\
SEt HyOMe
S-CHz HCOH
HYOH
I
H T H
HOYH HYOH
HYOH
HYOH
HYOH CHPOH
CHZOH
D-Glucose propane-1,&diyl dithioacetal
(1S)-D-Glucose S-ethyl Omethyl monothioacetal
OMe HCSMe HYOAc AcOCH HYOAc HCOAc I
CH~OAC
(1R)-2,3,4,5,6-Penta-O-acetyl-o-glucose dirnethyl rnonothioacetal
Note. In the last two examples, carbon atom 1 has become chiral. When known, the stereochemistry at this new chiral centre is indicated by the R,S system, as specified in 2-Carb-29.
NOMENCLATURE OF CARBOHYDRATES
125
2-Carb-31. Names for monosaccharide residues 2-Carb-31.1. Glycosyl residues The residue formed by detaching the anomeric hydroxy group from a monosaccharide is named by replacing the terminal ‘-e’ of the monosaccharide name by ‘-yl’. The general name is ‘glycosyl’ residue. Terms of this type are widely used in naming glycosides and oligosaccharides. For examples (including glycosyl residues from uronic acids), see 2-Carb-33.2. The term ‘glycosyl’ is also used in radicofunctional names, e.g. for halides such as the glucopyranosyl bromide in 2-Carb-24.1 and the mannopyranosyl fluoride in 2-Carb-16.1, and esters such as the glucopyranosyl phosphate in 2-Carb-24.2.1 and the mannopyranosyl nitrate in 2-Carb- 16.2.
2-Carb-31.2 Monosaccharides as substituent groups In order to produce names for structures in which it may be desirable for a non-carbohydrate portion to be cited as parent, prefix terms are required for carbohydrate residues linked through carbon or oxygen at any position on the main chain. These prefixes can be formed by replacing the final ‘e’ of the systematic or trivial name of a monosaccharide by ‘-n-C-yl’, ‘-n-O-yl’or ‘-n-yl’ (if there is no ambiguity). In each case the term ‘-yl’ signifies loss of H from position n. At a secondary position (e.g. in 2-deoxy-D-glucos-2-y1, below) the free valency is regarded as equivalent to OH for assignment of configuration. Examples: YHZ-
YHO
c=o
-CNH:!
HOYH
HOYH
HYOH
HYOH
HYOH
HYOH
CH,OH
CHZOH
1-Deoxy-D-fructos-1-yl
2-Amino-2-deoxy-~-glucos-2-yl
HoROM OH
(Methyl P-~-ribopyranosid-2-Oyl) FHO -?OH HOYH
YHO HCHTH
HYOH
HYOH
HYOH
HYOH
CH2OH
D-Glucos-2-Gyl
CHZOH
2-DeOxy-D-glUCOS-2-yl
NOMENCLATURE OF CARBOHYDRATES
126
The same endings can be used to form substituent prefixes for alditol residues. Examples: YHpOH
I
$HOH
HTH
H$OH
-7H HYOH
H T H
HYOH
HOCH I
CHZOH
CHpOH
L-Arabinitol-1-Cyl (cf. 2-Carb-18.4) (RIS to be specified at C-I)
3-Deoxy-D-mannitol-3-yl
The ending ‘-yl’ without locants signifies loss of OH from the anomeric position (see 2-Carb-31.1). Loss of H from the anomeric OH is indicated by the ending ‘-yloxy’, without locant. For examples see 2-Carb-33. The situation in which the anomeric OH is retained but H is lost from the anomeric carbon atom is indicated by use of the ending ‘-yl’ without locants in conjunction with the prefix ‘1-hydroxy-’ (not by the ending ‘-1-C-yl’). N.B. In this case, the anomeric prefix a or p refers to the free valency, not the OH group. Example:
1-Hydroxy-a-D-allopyranosyl
Examples of the use of substituent prefixes for carbohydrate residues:
I
COCl
4-( 1-Acetoxy-2,3,4,6-tetra-Oacetyl-a-D-allopyranosyl)benzoylchloride
+
“”%
F H 3
CH2--NH2-C~~t~~ OH
’coo-
K (1-Deoxy-D-fructopyranos-1-yl)-L-alanine
NOMENCLATURE OF CARBOHYDRATES
N,N-Bis-( 1-deoxy-o-fructopyranos-1-yl)-ptoluidine
HO OH S-(!Y-Deoxyadenosin-!Y-yl)-L-methionine (AdoMet) S-[(1-Adenin-9-yl)-l,5-dideoxy-~-~-ribofuranosd-yl]-~-methionine [trivial name Sadenosylmethionine(SAM)] CH,--S-S-H,C
H
&H
OH
OH
OH
OH
Bis(5-deoxy-~-~-ribofuranos-5-yl) disulfide or bis(5-deoxy-~-~-ribofuranosd-yl)disulfane CHzOH O "H O -H ONCH~COOH
(P-~-Glucopyranos-2-Oyl)aceticacid (more commonly named 2- Ocarboxymethyl-P-D-glucopyranose; see 2-Carb-2.1, note 2)
HOOC-CO
-CHZ -0 OMe
(Methyl a-~-glucopyranosid-4-Oyl)pyruvicacid [or methyl 4- O(oxalomethyl)-a-o-glucopyranoside]
127
NOMENCLATURE OF CARBOHYDRATES
128
H
3-(~-~-Glucopyranosyloxy)~ndole (or indol-3-yl 0-D-glucopyranoside); trivial name indican
HOCH, +c :H -20H HO
OMe
OMe
x=o Methyl 2-O(methyl 2-deoxy-a-~-glucopyranosid-2-yl)-a-D-glucopyranoside or bis(methyl2-deoxy-u-~-glucopyranosid-2-yl)ether
X=NH Bis(methy1 2-deoxy-a-~-glucopyranosid-2-yI)amine
2-Carb-31.3. Bivalent and tervdent groups The group formed by detaching one hydrogen atom from each of two (or three) carbon atoms of a monosaccharide is named by replacing the terminal ‘-e’ of the monosaccharide name by ‘-diyl’ (or ‘-triyl’), preceded by the appropriate locants. Examples:
Methyl P-~-talopyranose-2-C,4-Cdiylphosphinite or 2-C,4-C-(methoxyphosphanediyl)-~-~-glucopyranose or (2R,4S)-2-C,4-C-(methoxyphosphanediyl)-~-~-thre~hexopyranose
/
Me0
Methyl (ethyl 2,4-dideoxy-~-~-glucopyranoside-2,4-diyl)phosphinite or ethyl 2,4-dideoxy-2,4-(methoxyphosphanediyl)-~-~-glucopyranoside
Residues formed by detaching two (or three) hydrogen atoms from the same carbon atom may be named similarly.
NOMENCLATURE OF CARBOHYDRATES
129
Example: HC=PPh,
H
OH
(Methyl 6-deoxy-~-~-glucopyranosid-6-ylidene)triphenyl-~~-phosphane or methyl 6-deoxy-6-triphenyl-h5-phosphanylidene-~-~-glucopyranoside
Note. Names based on phosphane, rather than phosphine or phosphorane, are used in this document, as recommended in [14].
2-Carb-32.Radicals, cations and anions Naming procedures described in this section follow the recommendations given in
WI. 2-Carb-32.1. Radicals Names for radicals are formed in the same way as those for the corresponding substituent groups (see 2-Carb-31.2) Examples: CH,OMe I
c=o I
CH20Bn
MeOCH H+ En0
HqOMe CH20Me
1,3,5,6-Tetra-OmethyI-~-fructos-4-Oyl Tetra-O-benzyl-D-glucopyranosyl CHzOBn
BnO
OMe
2,3,4,6-Tetra- O-benzyl-1methoxy-D-glucopyranosyl
Carbenes are named analogously by use of the suffix '-ylidene'. Example:
HuMe
HO
OH
"
Methyl 2-deoxy-~-~-elythrcbpentopyranosid-2-ylidene
NOMENCLATURE OF CARBOHYDRATES
130
2-Carb-32.2. Cations
Cations produced by formal loss of H‘ from a carbon atom are denoted by replacing terminal ‘e’ with the suffix ‘-ylium’, in conjunction with appropriate locants and a ‘deoxy-’ prefix if necessary (cf. 2-Cab-31.2). Examples: /CHO
HO,
H,
/CHO
9+
?+
HO$H
HO$H
HFOH
HFOH
HYOH
HYOH
CH20H
CH20H
D-arabiffdiexos-2- Gylium
2-Deoxy-~-afabiffehexos-2-ylium
D-Glucopyranosylium
C+
3,4,6-Tri-Oacetyl- 1,2-Oethyliurndiyl-a-o-allopyranose
Cations formed by hydronation of an OH group or at the hemiacetal ring oxygen are denoted by the suffix ‘-0-ium’, with numerical locant. Examples: M
e
o
R
O
M
e
OMe
Methyl 3,4-di-0methyl-P-~-ribopyranosid-2-O-ium Meo*oMe OMe
Methyl 2,3,4-tri-Omethyl-~-~-ribopyranosid-5-Oium
NOMENCLATURE OF CARBOHYDRATES
131
2-Carb-32.3. Anions Anions produced by formal loss of H+ from an OH group are denoted by the suffix ‘ G a t e ’ , with numerical locant. Example: M
e
o
m
O
M
e
OMe
Methyl 3,4-di-Ornethyl-P-~-ribopyranosid-2-Oate
Anions produced by formal loss of H+ from a carbon atom are denoted by the suffix ‘-ide’, with appropriatelocants and a ‘deoxy-’prefix if necessary (cf. 2-Carb-31.2). Examples: HO
,CHO
H,
‘q-
,CHO
c-
HO$H
HO$H
HCOH
HYOH
HYOH
HYOH
CH2OH
CH20H
A
OMe
1,5-Anhydro-2,3,4,8tetra-Omethyl-o-glucitol-1-ide
2-Carb-32.4. Radical ions Radical ions can be named by adding the suffix ‘yl’ to ion names. Alternatively, the words ‘radical cation’ or ‘radical anion’ may be added after the name of the parent with the same molecular formula, especially when the location of the radical ion centre is not to be specified. Examples:
H
OH
D-Glucopyranosiurnyl,or o-glucopyranose radical cation
I32
NOMENCLATURE OF CARBOHYDRATES
‘(---I H,OH
HO
H
._
2-Deoxy-~-arabinehexos-2-id-2-yl
or 2-deoxy-D-arabinehexopyranos-2-ylideneradical anion
2-Carb-33. Glycosides and glycosyl compounds 2-Carb-33.1. Definitions Glycosides were originally defined as mixed acetals (ketals) derived from cyclic forms of monosaccharides. Example:
Methyl a-D-glucopyranoside
However, the term ‘glycoside’ was later extended to cover not only compounds in which, as above, the anomeric hydroxy group is replaced by a group -OR, but also those in which the replacing group is -SR (thio lycosides), -SeR (selenoglycosides), -NR’R2 (N-glycosides), or even -CR’R R3 (C-glycosides). ‘Thioglycoside’ and ‘selenoglycoside’ are legitimate generic terms; however the use of ‘N-glycoside’, although widespread in biochemical literature, is improper and not recommended here (‘glycosylamine’ is a perfectly acceptable term). ‘C-Glycoside’ is even less acceptable (see Note to 2-Cub-33.7). A glossary of terms based on ‘glycose’ is given in the Appendix.
!
Particularly in naturally occurring glycosides, the compound ROH from which the carbohydrate residue has been removed is often termed the aglycone, and the carbohydrate residue itself is sometimes referred to as the ‘glycone’. Note. The spelling ‘aglycon’ is often encountered. 2-Carb-33.2. Glycosides Glycosides can be named in three different ways: (a) By replacing the terminal ‘-e’ of the name of the corresponding cyclic form of the monosaccharide by ‘-ide’ and preceding this, as a separate word (the intervening space is significant), the name of the group R (see examples below).
133
NOMENCLATURE OF CARBOHYDRATES
Examples:
OOMe
H
C . HO ,H
HYOHOH
OH
HOCHZ
HO
Methyl a-o-gulofuranoside not methyl-a-D-gulofuranoside
Ethyl P-o-fructopyranoside
Meo@iHo HO HO
Methyl (6R)-o-gluc~hexodialdo-6,2-pyranoside
Note. This is the ‘classical’ way of naming glycosides. It is used mainly when the group R is relatively simple (e.g. methyl, ethyl, phenyl).
(b) By using the term ‘glycosyloxy-’, in the appropriate form for the monosaccharide, as prefix, for the name of the compound. Note. This prefix includes the oxygen of the glycosidic bond. An example is given in 2-Carb-3 1.2; more are given below. (c) By using the term ‘0-glycosyl-’ as prefix to the name of the hydroxy compound.
Note.This prefix does not include the oxygen of the glycosidic group. This is the appropriate method for naming natural products if the trivial name includes the OH group. The system is also used to name oligosaccharides (see 2-Carb-37). Examples: H-C-OH
COOH HoHo -s. OH
(20S)-20-Hydroxy-5p-pregnan-3a-yl p-D-glucopyranosiduronicacid or (20S)-3a-(~-~-glucopyranosyloxyuronicacid)-5P-pregnan-20-01; for biochemical usage, pregnanediol 3-glucuronide Note. A common biochemical practice would give the name (20S)-3a-(P-~-glucopyranuronosyloxy)-5~-pregnan-20-ol. This practice of naming glycosyl residues from uronic acids as ‘glycuronosyl’ is unsatisfactory because it implies the acceptance of the parent name ‘glycuronose’. However the use of a two-word substituent prefix (glycosyl-
134
NOMENCLATURE OF CARBOHYDRATES
oxyuronic acid), ending with a functional class name, remains inherently problematic, since it contravenes general organic nomenclature principles [13,14]. The latter practice has the advantage of retaining homomorphic relationships between glycoses and glycuronic acids. CHPOH
H
OH
4-Acetylphenyl P-D-glucopyranoside or 4'-(P-D-glucopyranosyloxy)acetophenone; trivial name picein
(S)-0-P-D-Glucopyranosylmandelonitrile
or (S)-(P-D-glucopyranosyloxy)(phenyl)acetonitrile; trivial name sambunigrin
7-(~-~-Glucopyranosyloxy)-8-hydroxycoumarin; trivial name daphnin
H
OH
8-P-o-Xylopyranosyl-L-serine [(xy~-)ser] Glycosides can be named as substituents by the methods of 2-Carb-31.
/cw \'
NOMENCLATURE OF CARBOHYDRATES
Example:
H
135
OH
OH H
OH
(Methyl 5-deoxy-~-o-xylofuranosid-5-yl) 2-(4-hydroxy-3-methoxyphenyl)-7methoxy-5-[2-(methyl ~-o-xylofuranosid-5-Oylcarbonyl)vinyl]-2,3-dihydrobenzofuran-3-carboxylate
2-Carb-33.3. Thioglycosides Names for individual compounds can be formed, like those for glycosides, in three ways, as follows. (a) By using the term thioglycoside, preceded by the name of the group R.
(b) With the prefix 'glycosylthio-', followed by the name of the compound RH; this prefix includes the sulfur atom. (c) With the prefix 'S-glycosyl-' (not including the S atom), followed by the name of the thio compound. Sulfoxides and sulfones can also be named by functional class nomenclature [ 13, 141. Examples:
CH20H
H o H i X & LOH S E f
OH
OH
Ethyl 1-thio-P-D-glucopyranoside 4-(cw-~-RibofuranosyIthio)benzoic acid or 4-carboxyphenyl 1-thio-a-D-ribofuranoside
136
NOMENCLATURE OF CARBOHYDRATES OSOaK
I
CHiOH H C $ - C ?
C H d H =CH2
HO H
OH
S~-D-Glucopyranosyl(2')-O(potassium sulfonato)but-3-enehydroximothioate (trivial name sinigrin)
ph/% 0
Phenyl tetra-Oacetyl-a-D-glucopyranosyl sulfoxide or phenyl 2,3,4,6-tetra-Oacetyl-l -thio-a-D-glucopyranosideSoxide
2-Carb-33.4. Selenoglycosides Names are formed analogously to those for thioglycosides (2-Carb-33.3). Examples:
2-Carboxyethyl 1-seleno-9-D-xylopyranoside or 3-(~-~-xylopyranosylseleno)propanoicacid
OH
OH
Sep-o-Ribopyranosyl-D-selenocysteine or (S)-2-amino-2-carboxyethyl1-seleno-9-o-ribopyranoside or 3-(~-D-ribopyranosylseleno)-D-alanine
2-Carb-33.5. Glycosyl halides Compounds in which the anomeric hydroxy group is replaced by a halogen atom are named as glycosyl halides. Pseudohalides(azides, thiocyanates etc.) are named similarly.
NOMENCLATURE OF CARBOHYDRATES
137
Examples: CH~OAC0
Aco-=9 br
Tetra-Oacetyl-a-D-mannopyranosylbromide
Br
Methyl (2,3,4-tri-Oacetyl-a-~-glucopyranosyl)uronate bromide not methyl 2,3,4-tri-Oacetyl-l -bromo-1-deoxy-a-D-glucopyranuronate
3,4,6-Tri-Obenzyl-a-~-arabino-hexopyranosyl-2-ulose bromide CHO
I
(CfBr OBn
BnO
3,4,5-Tri-Obenzyl-a-~-arabino-hexos-2-ulo-2,6-pyranosyl bromide or 3,4,5-tri-Obenzyl-a/dehydoa-~-arabino-hexosQ-ulopyranosyl bromide COOMe
AcNH OAc
Methyl (5-acetamido-4,7,8,9-tetra-Oacetyl-3,5-dideoxy-~-glycer~a-~-ga/actonon-2-ulopyranosyl)onatechloride
2-Carb-33.6. N-Glycosyl compounds (glycosylamines) N-Glycosyl derivatives are conveniently named as glycosylamines. In the case of complex heterocyclic mines, such as nucleosides, the same approach is used.
138
NOMENCLATURE OF CARBOHYDRATES
Examples: 0
KPhenyl-a-D-fructopyranosylamine not aniline a-D-fructopyranoside
1-P-D-Ribofuranosyluracil (trivial name uridine)
N1-(2-Acetamido-2-deoxy-~-o-glucopyranosyl)-~-lysinamide (Lys-NH-GlcNAc) [trivial name N'-(N-acetylglucosaminyl)-~-lysinamide]
HO OH 9-(5-S-Methyl-5-thio-p-~-ribofuranosyl)adenine
GOOH
H,N-G-H
hP-(2-Acetamido-2-deoxy-~-~-glucopyranosyl)-~-asparagine [(GlcNAc-)Asn] or 2-acetamido-N' -~-~-aspartyl-2-deoxy-~-~-glucopyranosylamine (trivial name p-N-acetylglucosaminyl-L-asparagine)
NOMENCLATURE OF CARBOHYDRATES
139
CON& "OH% NH
HO&NH2
OH HO
Bis(a-D-glucopyranosylur0namide)arnine
2-Carb-33.7. C-Glycosyl compounds Compounds arising formally fiom the elimination of water from the glycosidic hydroxy group and an H atom bound to a carbon atom (thus creating a C-C bond) are named using the appropriate 'glycosyl-' prefixes (or other methods as appropriate, avoiding 'C-glycoside' terminology). Note. The term C-glycoside, introduced for naming pseudouridine (a nucleoside from transfer RNA), is a misnomer. A11 other glycosides are hydrolysable; the C-C bond of 'C-glycosides' is usually not. The use and propagation of names based on 'C-glycoside'
terminology is therefore strongly discouraged. Example:
4-~-~-Glucopyranosylbenzoic acid not 4-carboxyphenyl CP-D-glucopyranoside
H
O
C
W
"
"
H
HO
A
8-(2-Deoxy-~-D-erythrc-pentofuranosyl)adenine not adenine 8-(2-deoxyriboside) 0
HO
OH
5-P-~-Ribofuranosyluracil;trivial name pseudouridine
140
NOMENCLATURE OF CARBOHYDRATES CHZOH cH2cN OH
3,7-Anhydro-2-deoxy-o-glycero-~-gulo-octononitrile or 2-C(p-o-glucopyranosyl)acetonitrile not cyanomethyl Cp-o-glucopyranoside
HO
OH
2-~-~-Glucopyranosyl-1,3,6,7-tetrahydroxyxanthen8-one; trivial name rnangiferin
CHzOH
(1 09-10-p-D-Glucopyranosyl-i,8-dihydroxy-3-(hydroxyrnethyl)anthracen9(1OH)-one; trivial names aloin A, (109-barbaloin
HO HO OH
0
6-p-o-Glucopyranosyl-4',5,7-tri hydroxy-8-a-~-rhamnopyranosylf lavone; trivial name violanthin
2-Carb-34. Replacement of ring oxygen by other elements 2-Carb-34.1. Replacement by nitrogen or phosphorus Names should be based on those of the amino sugars (see 2-Carb-14) (or the analogous phosphanyl sugars) with the amino or phosphanyl group at the nonanomeric position. Ring-size designators (furano, pyrano etc.) are the same as for the oxygen analogues.
NOMENCLATURE OF CARBOHYDRATES
141
Examples:
5-Arnino-&deoxy-~-glucopyranose; trivial name nojirimycin
1-Amino-I ,5-anhydro-1-deoxy-D-mannitolor 1,5-dideoxy-l,5-imino-o-mannitol; trivial name deoxymannojirimycin
Note the extension of the use of ‘anhydro’ in the above example to include the elimination of water between -NH2 and -OH(cf. 2-Cub-26). Et CH,OH H
o
H
q
OHOH
5-Deoxyd-ethylamino-a-~-glucopyranose H
5-Deoxy-5-phosphanyl-~-xylopyranose
Note. Use of the terms ‘aza sugar’, ‘phospha sugar’ etc. should be restricted to structures where carbon, not oxygen, is replaced by a heteroatom. Thus the structure below is a true aza sugar. The term ‘imino sugar’ may be used as a class name for cyclic sugar derivatives in which the ring oxygen atom has been replaced by nitrogen.
OMe
Methyl 3-deoxy-3-aza-cx-o-ribo-hexopyranoside
2-Carb-34.2. Replacement by carbon The (non-detachable) prefix ‘carba-’ signifies replacement of a heteroatom by carbon in general natural product nomenclature [26], and may be applied to replacement of the hemiacetal ring oxygen in carbohydrates if there is a desire to stress homomorphic relationships. If the original heteroatom is unnumbered, the new carbon atom is assigned the locant of the non-anomeric adjacent skeletal atom, with suffix ‘a’.
142
NOMENCLATURE OF CARBOHYDRATES
Note. The draft natural product rules [26] recommend that the new carbon atom takes the locant of the lower-numbered proximal atom. However, carbohydrate chemists regard the ring oxygen as formally originating from the non-anomeric (usually higher-numbered) position.
Additional stereochemistry (if any) at the new carbon centre is specified by use of the RIS system ([13], Section E). Structures of this type can also be named as cyclitols [ 8 ] . Examples: CH2OH O H -" HO OH
0
HO
H
1-(2-Deoxy-4a-carba-~-~-erythr~pentofuranosyl)thymine
or 4'a-carbathymidine
HOC 5 Qo2
H
CHzOH
HO
H
NOMENCLATURE OF CARBOHYDRATES
143
VcH3 0
HN
YOAN 4'
H HO
1-[(4aS)-2-Deoxy-4a-fluoro-4a-ca~a-~-~-erythro-pentof uran0syl)thymine or (4'aS)-4'a-fluoro4'a-carbathymidine
2-Curb-35. Carbohydrates containing additional rings Internal bridging of carbohydrate structures by bivalent substituent groups creates additional rings, which can be named either by use of a substituent prefix representing the bridging group, or by fusion nomenclature. The following recommendations for the use of these two approaches are not thoroughly developed; they simply represent an attempt to rationalize and codify current literature practice in the use of systems not in general well suited to carbohydrate applications. Bridging substituent prefix nomenclature (2-Carb-35.1) is based on the system well established €orsimple cyclic acetals (2-Carb-28), and fusion nomenclature (2-Carb-35.2) on current literature usage and requirements for general natural product nomenclature [26].
2-Carb-35.1. Use of bivalent substituent prefixes Where the new bridge is attached to oxygen (or a replacement heteroatom, e.g. nitrogen in an amino sugar) already indicated in the name of the unbridged carbohydrate, the bivalent substituent prefix denotes substitution at two heteroatoms as outlined in 2-Cab-24.1 and 2-Carb-25 [method (b)]. Heteroatoms not directly bonded to the carbohydrate chain are regarded as part of the bridge. Where the new bridge is attached through C-C bonds to the carbohydrate chain, the bridge prefix denotes a double C-substitution. Procedures are as outlined in 2-Carb16.
Examples: CHzOH
I
Me&, o,$,8*ltQ o.
0
I
O/CMe2
2,3:4,5-Di-Oisopropylidene-P-~-fructopyranose
Note 1.The alternative fusion name (see2-Carb-35.2) is 2.2,2',2'-tetramethy1-4,4',5,5'-tetrahydro-(2,3,4,5-tetradeoxy-~-D-f~ctopyranoso)[2,3-d:4,5-d]b~s[ 1,3]dioxole; this is clearly less desirable on grounds of complexity.
144
NOMENCLATURE OF CARBOHYDRATES
Note 2. The use of prefixes ending in ‘-ylidene’ for gem-bivalent substituent groups is traditional in the carbohydrate field, although no longer recommended in general organic nomenclature [ 141. COOMe
Methyl [(5)-4,6-0(1 -methoxycarbonylethylidene)]-P-~-mannopyranoside
Methyl 2,3-(butane-l,4-diyl)-2,3-dideoxy-P-~-glucopyranoside
Note. The alternative fusion name (see 2-Carb-35.2) is hexahydro(methy12,bdideoxy-P-Dglucopyranosido)[2,3]benzene CH2OH
Methyl 2,3-(buta-1,3-diene-l,4-diyl)-2,3-dideoxy-P-~-erythro. hex-2-enopyranoside
Note. The alternative fusion name (see 2-Carb-35.2) is (methyl 2,3-dideoxy-P~-erythrohexopyranosido)[2,3]benzene
1,6-Anhydro-2,3-dideoxy-2,3-(9,1O-dihydroanthracene-9,1O-diyl)-P-D-ribohexopyranos-4-ulose
NOMENCLATURE OF CARBOHYDRATES
145
(1S)-l,5-Anhydro-3,4,6-tri-Dbenzyl-l -C,2-0(ephenylenemethy1ene)-D-mannitol
Note. The isomeric chromene would be named as a 2-0,l-C-substituted system.
The prefix ‘cyclo-’ may be used for a single-bond bridge [ 141.
Examples:
- YH
A ~ N
OAc OMe
Methyl 4-Kacetyl-2,3-di-Oacetyl-4,6-diamino-4,6-Kcyclo-4,6-dideoxy-a~galactopyranoside
AcO P O bAc M
e
Methyl 2,3-di-Oacetyl-4,6-cyclo-4,6-dideoxy-~-~-galactopyranoside 2-Carb-35.2. Ring fusion methods Fusion methods are employed as in general natural product nomenclature [26], except that the original carbohydrate ring is cited first, in parentheses (with terminal ‘-e’, if present, replaced by ‘-0’). For designating stereochemistry, bonds in the new ring are considered as equivalent to OH, unless OH (or its equivalent) is still present at the ring junction. Substituents on the carbohydrate portion are included within the parentheses enclosing the fusion prefix. Substituents on the new ring (including ‘hydro-’ prefixes) precede the carbohydrate term(s). If there is a choice, the new ring is numbered in the direction used to define the fusion locants. Note. General natural product fusion nomenclature [26] would require the carbohydrate portion to be cited last (e.g. oxazologlucopyranose),whereas it is cited first here and in the literature.
Examples:
Ph
Po
146
NOMENCLATURE OF CARBOHYDRATES
Note 1.The alternative name using a substituent prefix (see 2-Carb-35. I) is 2-amino-1-0.2N-(benzylylidene)-2-deoxy-a-~-glucopyranose. Note 2. Literature fusion names for this type of compound use ‘glucopyrano[2,1-d]oxazoline’ terminology. However, names for partially hydrogenated heterocycles ending in ‘oline’ were abandoned by IUPAC in 1983 [27], in favour of ‘dihydro......ole’. Use of ‘pyranoso’ rather than ‘pyrano’ is recommended to avoid confusion with the normal fusion prefix from ‘pyran’ and to simplify rules for naming derivatives (e.g. glycosides).
*%q CH~OAC
MeNH
Yo
2-Methylamino-4,5-dihydro-(3,4,6-tri-O-acetyl-l,2-dideoxy-a-oglucopyranoso)[2,1-d]-1,Soxazole Note. The alternative name using a substituent prefix (see 2-Carb-35.1) is 3,4,6-tri-0acetyl-2-amino-2-deoxy- 1-0,2-N-[ (methylamino)methylylidene]-a-~-glucopyranose, CHpOH 0 “OH<*
Ir““
0
3-Phenyltetrahydro-(1,2-dideoxy-a-D-glucopyranoso)[1,2-d]imidazol-2-one Note. The alternative name using a substituent prefix (see 2-Carb-35.1) is 2-amino-1.2-Ncarbonyl- 1,2-dideoxy- 1-~-phenyl-a-~-glucopyranosylamine
zo
AcO CH& CH3
2-Methyl-5,6-dihydro-(4-Oacetyl- 1,2,3,6-tetradeoxy-3-methyl-a-~-ribe hexopyranoso)[3,2,1-de]-4Kl,3-oxazine Note 1. The alternative name using a substituent prefix (see 2-Carb-35.1) is 4-0-acetyl-3amino-2,3,6-trideoxy- 1-0,3-N-(ethan- 1-yl- 1-ylidene)-3-C-methyl-a-~-ribo-hexopyranose Note 2. This example would not normally be regarded as a fused system for nomenclature purposes, since it is not orfho-or ortho- and peri-fused [ 131.
2-Carb-35.3. Spiro systems Spiro systems can be named by normal procedures [ 131. For clarity, any anhydro or deoxy prefixes or chalcogen replacement prefixes (e.g. thio) refemng to the spiro
NOMENCLATURE OF CARBOHYDRATES
147
junction should appear next to the carbohydrate stem. The carbohydratecomponent is cited first. Configuration at the spiro junction is assigned by the R,S system. Examples:
Ph
(1 R)-2,3,4,6-Tetra-Oacetyl-3'-phenylspiro[l,5-anhydro-D-glucitol-l,!5'[1,4,2]oxathiazole]
(3S)-5-OBenzoyl-l ',2'-dihydro-l,2-Qisopropylidenespiro[3-deoxy-cl-~-erythm
pentofuranose-3,3'-naphtho[l,2-e][l,3]oxazin]-T-ol The following spiro disaccharide example is best named by use of a gem-bivalent substituent prefix: CH2OH
HOCH2U
O
H
OH
Methyl 2,3-OD-glucopyranosylidene-~-~-rnannopyranoside
Stereochemistry at C-1 of the glucose residue could be indicated as R or S, e.g. [(1 R)-2,3-O-D-glucopyranosylidene] .....
NOMENCLATURE OF CARBOHYDRATES
148
2-Carb-36. Disaccharides
2-Carb-36.1. Definition A disaccharide is a compound in which two monosaccharide units are joined by a glycosidic linkage.
2-Carb-36.2.Disaccharides without a free hemiacetal group Disaccharides which can be regarded as formed by reaction of the two glycosidic (anomeric) hydroxy groups with one another are named, systematically, as glycosyl glycosides. The parent (cited as the 'glycoside' component) is chosen according to 2-Carb-2.1. Both anomeric descriptors must be included in the name. Examples:
HOH O -& . CHzOH
a-D-Glucopyranosyl a-D-glucopyranoside [a-D-Glcp(1~l )-a-D-Glcp] (trivial name a,a-trehalose)
OH
P-D-Fructofuranosyl a-o-glucopyranoside [P-~-Fruf-(2~1 )-a-~-Glcp] not a+-glucopyranosyl P-D-fructofuranoside (trivial names sucrose, saccharose) Note. Such disaccharides are also known as non-reducing disaccharides. If derivatives are named on the basis of the trivial name, the component cited first in the systematic name receives primed locants.
NOMENCLATURE OF CARBOHYDRATES
I49
Example:
c H ’ c CHzOH o o HO
4,6,6‘-Trichloro-4,6,6‘-trideoxygalactosucrose or 6-chioro-6-deoxy-j3-~-fructofuranosyl4,6-dichloro-4,6-dideoxy-a-Dgalactopyranoside (‘galactosucrose’ is a trivial name for the 4-epimer of sucrose)
2-Carb-36.3. Disaccharide with a free hemiacetal group A disaccharide in which one glycosyl unit has replaced the hydrogen atom of an alcoholic hydroxy group of the other is named as a glycosylglycose. The locants of the glycosidic linkage and the anomeric descriptor(s) must be given in the full name.
There are two established methods in use for citing locants: either in parentheses between the glycosyl and glycose terms, or in front of the glycosyl prefix, as in the names of glycosides. The former (preferred) method is derived from that used to designate residues in oligosaccharides (see 2-Carb-37 and -38). Note. The latter method is that used by Chemical Abstracts Service for disaccharides.
The 0-locants used for the former method in the previous recommendations [ 11 are omitted here. Examples:
a-D-Glucopyranosyl-(1+4)-P-o-glucopyranose [a-o-Glcp( 1+4)-P-o-Glcp] or 4-Oa-~-glucopyranosyl-~-~-glucopyranose (trivial name 0-maltose, not 8-o-maltose)
NOMENCLATURE OF CARBOHYDRATES
150 HO
HO
OH OH
P-D-Galactopyranosyl-(1-)4)-a-~-glucopyranose[P-D-Galp(1-+4)-a-D-Glcp] or 4-O~-~-galactopyranosyl-a-o-glucopyranose (trivial name a-lactose, not a-D-lactose) HO
HO HO
P-D-GalaCtOpyranosyl-(1+4)-N-acetyl-o-glucosamine (trivial name Kacetyllactosamine; LacNAc) Note. Disaccharides with a free hemiacetal group are also known as reducing disaccharides.
2-Carb-36.4Trivial names Many of the naturally occurring disaccharides have well established trivial names. Some of these are listed below, together with the systematic names in both versions (see above). Cellobiose
~-D-Glucopyranosyl-(1-+4)-~-glucose 4-OP-D-GlUCOpyranOSyI-D-glUCOSe
Gentiobiose
P-D-Glucopyranosyl-(1-+6)-D-glUCOSe
6-~~-~-Glucopyranosyl-~-g~ucose lsomaltose
a-D-Glucopyranosyi-(1-+6)-D-glUCOSe
6-Oa-~-Glucopyranosyl-D-g~ucose Melibiose
a-D-Galactopyranosyl-(1+6)-~-glucose 6-Oa-D-GalaCtOpyranOSyl-D-glUCOSe
Primeverose
P-D-Xylopyranosyl-(1+6)-D-glUCoSe
6-O~-~-Xylopyranosyl-~-glucose Rutinose
a-L-Rhamnopyranosyl-(1+6)-D-glUCOSe
6-Oa-L-Rhamnopyranosyl-D-glucose The systematic names of trehalose, sucrose, maltose and lactose have been given already (with the formulae).
NOMENCLATURE OF CARBOHYDRATES
151
If derivatives are named on the basis of the trivial name, the component cited first in the systematic name receives primed locants. Example:
AcO
AcO OAc
1,2,2',3,3',4',6-Hepta-Oacetyl-~-Otosyl-a-cellobiose or 2,3,4-tri-Oacetyl-6-Qtosyl-~-D-glucopyranosyl-(1+4)-1,2,3,6-tetra-Oacetyl-aD-glucopyranose
If the reducing terminal is a uronic ester glycoside, the ester alkyl group is cited at the beginning of the name, and the aglyconic alkyl group is cited with the name of the glycosidic residue. Example:
1+4)Methyl (3-~acetyl-6-deoxy-2,4-di-~methyl-a-~-galactopyranosyl)-( (ally1 2,3-di-Obenzoyl-~-~-glucopyranosid)uronate
2-Carb-37. Higher oligosaccharides 2-Carb-37.1. Oligosaccharides without a free hemiacetal group Trisaccharides (for example) are named as glycosylglycosylglycosides or glycosyl glycosylglycosides as appropriate. A choice between the two residues linked through their anomeric positions for citation as the 'glycoside' portion can be made on the basis of 2-Carb-2.1. Alternatively, a sequential (end-to-end) naming approach may be used, regardless of 2-Carb-2.1. The names are formed by the preferred method of naming disaccharides (see 2-Cab-36.3): the locant of the anomeric carbon atom, an arrow, and the locant of the connecting oxygen of the next monosaccharide unit are set in parentheses between the names of the residues concerned.
152
NOMENCLATURE OF CARBOHYDRATES
bH
PD- Fructofuranosyl a-D-galactopyranosyl-(1+6)a-~-glucopyranoside (glucose preferred to fructose for citation as ‘glycoside’) or a-D-galactopyranosyl-(1-16)-a-D-glUCOpyranOSyl p-D-f ructofuranoside (sequential method) [a-D-Galp( 1+6)-a-D-Glcp( 1-2)P-o-FrufJ (trivial name raffinose)
0
HO
HOcGsI CH20H
H
HO
H
P-D-Fructofuranosyl-(2-+1)-P-~-fructofuranosyl-(2+1)-P-D-fructofuranosyl a-D-glucopyranoside [P-D-Fruf-(2-11)-P-D-Fruf-(2+1 )-P-D-FrUf-(2(+1) a - ~ - G k]p (trivial name nystose)
NOMENCLATURE OF CARBOHYDRATES
153
If derivatives are to be named on the basis of the trivial name, the component cited last in the systematic name receives locants with no primes, the preceding component singly-primed locants, etc. However, naming of trisaccharide and higher oligosaccharide derivatives systematically is preferred, to avoid ambiguity.
2-Carb-37.2. Oligosaccharides with a free hemiacetal group An oligosaccharide of this class is named as a glycosyl[glycosyl]nglycose, i.e. the reducing sugar is the parent. Anomeric descriptors and locants are given as described in 2-Carb-37.1. The conventional depiction has the reducing sugar (glycose residue) on the right and the non-reducing end (glycosyl group) on the left. Internal sugar units are called glycosyl residues (the term ‘anhydrosugar unit’ is misleading and its use is discouraged). As the reducing end is often converted into the corresponding alditol, aldonic acid or glycoside derivative, the more general term ‘downstream end’ has been proposed for this end of the molecule. Examples:
a-D-Glucopyranosyl-(1+6)-a-D-glucopyranosyl-( 1+4)-~-glucopyranose (trivial name panose)
P-D-Glucopyranosyl-(1+4)-P-D-glucopyranosyl-( 1-+4)-D-glucopyranose (trivial name cellotriose)
154
NOMENCLATURE OF CARBOHYDRATES
HO
HO
Methyl (sodium a-L-idopyranosy1uronate)-(1+4)-(2-acetamidoQ-deoxya-D-glucopyranosy1)-(1+4)-(sodium P-o-glucopyranosy1uronate)-(1+3)P-D-galactopyranoside {Nan[a-~-ldopA-(1+4)-a-~-GlcpNAc-(1+4)-P-~-GlcpA-( 1+3)-P-~-GalpOMe])
Higher oligosaccharides are named systematically in the same way. However, it is often preferable to give their structures by use of the symbolic approach outlined in 2-Carb-38). Trivial names for linear oligosaccharides consisting only of 1+4 linked a-D-glucopyranosyl residues are maltotriose, maltotetraose etc. Similar names, based on the component sugar, are convenient for refemng to other homo-oligosaccharides (e.g. xylobiose, galactotetraose), but such names should be used sparingly. Locants for naming substituted derivatives may be obtained by assigning roman numerals to the residues in ascending order starting from the reducing end. Example:
111 CH20H
6'V-OTritylmaltotetraose
Arabic numerals have also been used in this context, but confusion may result when component sugar residues have structural modifications (e.g. chain branches) requiring superscript locant numbers. The present recommendation follows longestablished usage in glycolipids [21].
NOMENCLATURE OF CARBOHYDRATES
155
2-Carb-37.3.Branched oligosaccharides Terms designating branches should be enclosed in square brackets. In a branched chain, the longest chain is regarded as the parent. If two chains are of equal length the one with lower locants at the branch point is preferred, although some oligosaccharides are traditionally depicted otherwise, such as the blood group A trisaccharide exemplified below. Examples:
a-D-Glucopyranosyl-(1+4)-[a-~-glucopyranosyl-(1 +6)]-D-glUCOpYranOS€? [or 4,6-di- O(a-D-gluc0pyranosyl)-D-glucopyranose] (trivial name isopanose) OH
COOH
HO
I
HO
(5-Acetamido-3,5-dideoxy-~-glycer~a-~-galact~non-2-ulopyranosylonic acid)(2+3)-P-~-galactopyranosyI-(1+3)-[a-~-fucopyranosyl-(1+4)]2-acetamido-2-deoxy-o-glucopyranose or 5-Kacetyl-a-neuraminyl-(2+3)-~-~-galactopyranosyl-( 1 +3)[a-L-fucopyranosyl-(1+4)]-2-acetamido-2-deoxy-~-glucopyranose {a-Neup5Ac-(2-+3)-P-D-Galp(1+3)-[a-~-Fucp(1 +4)]-~-GlcpNAc) (sialyl-Leatrisaccharide)
NOMENCLATURE OF CARBOHYDRATES
156 HO
““@H HO HO
2-Acetamido-2-deoxy-acr-D-galactopyranosyl-( 1+3)-[a-~-fucopyranosyl-(1+2)]D-galactopyranose (a-D-GalpNAc-(1+3)-[a-~-Fucp(1+2)]-~-Galp)(blood group A trisaccharide)
2-Carb-37.4. Cyclic oligosaccharides 37.4.1. Semisystemtic names Cyclic oligosaccharides composed of a single type of oligosaccharide unit may be named semisystematically by citing the prefix ‘cyclo’, followed by terms indicating the type of linkage [e.g. ‘malto’ for a-(l+4)-linked glucose units], the number of units (e.g. ‘hexa’ for six) and the termination ‘-ose’. The trivial names a-cyclodextrin (a-CD) for cyclomaltohexaose, p-cyclodextrin (p-CD) for cyclomaltoheptaose and y-cyclodextrin (y-CD) for cyclomaltooctaose are well established. Example:
Cyclomaltohexaose (a-cyclodextrin, a-CD)
Structures with linkages other than (1+4) should be named systematically (see 2-Cab-37.4.2).
NOMENCLATURE OF CARBOHYDRATES
I57
Note. The cyclic oligosaccharides arising from enzymic transglycosylation of starch have been referred to as Schardinger dextrins. These names (and those of the cyclohexaamylose type) are not recommended, but the abbreviation CD is tolerated.
Derivatives with the same substitution pattern on each residue can be named semisystematically by assigning a single multiplicative prefix (e.g. hexakis, heptakis etc.) to the substituent prefixes as a group. Example:
OMe
Heptakis(6-deoxy-6-iodo-2,3-di-Omethyl)cyclomaltoheptaose
Derivatives with different substitution patterns on the various residues can be named by the method of 2-Carb-37.2, assigning a roman numeral to each residue. Example: CHpNH2
HOHpC
CHzOH
6'-Amino-6'-deoxycyclornalto hexaose 37.4.2. Systematic names Cyclic oligosaccharides composed of a single type of residue can be named by giving the systematic name of the glycosyl residue, preceded by the linkage type in parentheses, preceded in turn by 'cyclo-' with a multiplicative suffix (i.e. 'cyclohexakis-' etc.)
NOMENCLATURE OF CARBOHYDRATES
158
Examples:
[Ggl CHZCN
OH
m 1
Cycloheptakis-( 1~4)-(6-deoxy-a-~-gluceheptopyranosylurononitrile) CH2CH2NHz
OH OH
-
Cycloheptakis-( 1~4)-(7-aminoB,7-dideoxy-a-~-gluceheptopyranosyI) The 1 4 6 isomer of cyclomaltohexaose should be named cyclohexakis-(l+6)-aD-glucosyl, rather than cycloisomaltohexaose.
2-Carb-37.5. Oligosaccharide analogues
Structures in which the linking glycosidic oxygen is replaced by -CH2- may be named by use of the replacement prefix 'carba-' (cf. 2-Cab-34.2) for emphasis of homomorphic relationships. The oxygen replaced is given the locant of the carbon atom to which it is attached in the residue with the lower roman numeral (cited as superscript) ( c ! 2-Carb-37.2), with suffix 'a'. Example:
II
0
HO
I
I
OH
If the glycosidic oxygen link is replaced by -0-NH-, normal amino sugar nomenclature can be employed.
NOMENCLATURE OF CARBOHYDRATES
159
Example:
OH
4- (2,6-Dideoxy-4-thioa-o-arabin~hexopyranosyloxyam~no)-4,6-dideoxy-
a-D-glucopyranose
2-Carb-38. Use of symbols for defining oligosaccharide structures* 2-Carb-38.1. General considerations Oligosaccharide and polysaccharide structures occur not only in free form but often as parts of glycopeptides or glycoproteins [ l l ] or of glycolipids [21]. It can be cumbersome to designate their structures by using the recommendations of 2-Carb37. The use of three-letter symbols for monosaccharide residues is therefore recommended. With appropriate locants and anomeric descriptors, long sequences can thus be adequately described in abbreviated form. Symbols for the common monosaccharide residues and derivatives are listed in Table 2. They are generally derived from the corresponding trivial names. Abbreviations for substituents (see 2-Carb- 1.16.2), preceded by locants, follow the monosaccharide abbreviations directly.
2-Carb-38.2. Representations of sugar chains For writing the structure of an oligo- or poly-saccharide chain, the glycose residue [the ‘reducinggroup’, i.e. the residue with the free hemiacetal group or modification thereof (e.g. alditol, aldonic acid, glycoside)] should be at the right-hand end. Also, when there is a glycosyl linkage to a non-carbohydrate moiety (e.g. protein, peptide or lipid) the glycosyl residue involved should appear at the right. Numbering of monosaccharide units, if desired, should proceed from right to left.
* The recommendations presented here are a modified version of the published recommendations [ 6 ] .
1980
160
NOMENCLATURE OF CARBOHYDRATES
Table 2. Symbols for monosaccharide residues and derivatives in oligosaccharide chains
Abequose
Abe
lduronic acid
IdoA
Allose
All
Lyxose
Altrose
Alt
Mannose
LYX Man
Apiose
Api
Muramic acid
Mur
Arabinose
Ara
Neuraminic acid
Neu
Arabinitol
Ara-ol
KAcetylneuraminic acid
NeuSAc
2-Deoxyribose
dRib
NAcetyl-2-deoxyneur-Benaminic acid
Neu2en5Ac
Fructose
Fru
KGlycoloylneuraminicacid Neu5Gc
Fucose
Fuc
3-Deoxy-~-manne oct-2-ulosonic acid
Kdo
Fucitol
FUC-01
Rhamnose
Rha
Galactose
Gal
3,4-Di-Omethylrhamnose
Rha3,4Me2
Galactosamine
GalN
Psicose
Psi
KAcetylgalactosamine
GalNAc
Quinovose
Qui
P-D-Galactopyranose 4-sulfate
P-D-Galp4S Ribose
Rib
Glucose
Glc
Ribose 5-phosphate
Rib5P
Glucosamine
GlcN
Ribulose
Ribulo (or Rul)
2,3-Diamino-2,3-dideoxy- GlcN3N o-glucose
Sorbose
Sor
Glucitol
Glc-01
KAcetylglucosamine
GlcNAc
Tagatose Talose
Tag Tat
Glucuronic acid
GlcA
Ethyl glucopyranuronate GlcpAGEt
Xylose Xylulose
XYl Xylulo (or Xul)
Gulose
Gul
2-CMethylxylose
Xyl2CMe
ldose
Ido
NOMENCLATURE OF CARBOHYDRATES
161
2-Carb-38.3. The extended form This is the form employed by the carbohydratedatabank CarbBank, and is preferred for most purposes. Each symbol for a monosaccharide unit is preceded by the anomeric descriptor and the configuration symbol. The ring size is indicated by an italic f for furanose or p for pyranose, etc. The locants of the linkage are given in parentheses between the symbols; a double-headed m o w indicates a linkage between two anomeric positions. In CarbBank, omission of a l p , D/L,orflp means that this structural detail is not known. Examples: a-D-Galp(l+6)-a-D-Glcp( 1 ++2)-P-D-Fruf for raffinose (see 2-Carb-37.1) P-~-Glcp( 1+4)-P-~-Glcp(1 +4)-~-Glcfor cellotriose (see 2-Garb-37.2)
Branches are written on a second line, or in brackets on the same line. Example: a-D-Glcp 1
J. 6 a-0-Glcp( 1+4)-~-Glc
or a-0-Glcp( 1-+4)[a-~-Glcp( 1 +6)]-~-Glc not
a-D-Glcp 1
1 4 1+6)-D-Glc a-~-Glcp( (see [lI], 2-Carb-37.3)
for 4,6-Di-Oa-~-glucopyranosyl-o-glucose
The hyphens may be omitted, except that separatingthe configurational symbol and the three-letter symbol for the monosaccharide.
2-Carb-38.4. The condensed form In the condensed form, the configurational symbol and the letter denoting ring size are omitted. It is understood that the configurationis D (with the exception of fucose and iduronic acid which are usually L) and that the rings are in pyranose form unless otherwise specified. The anomeric descriptor is written in the parentheses with the locants.
NOMENCLATURE OF CARBOHYDRATES
162
Example: Gal(a1-6)Glc(ai-2P)Fruffor raffinose For most purposes, the short form (2-Carb-38.5)is preferred when abbreviation of the extended form is desirable.
2-Carb-38.5. The short form
For longer sequences, it is desirable to shorten the notation even further by omitting (i) locants of anomeric carbon atoms, (ii) the parentheses around the locants of the linkage and (iii) hyphens (if desired). Branches can be indicated on the same line by using appropriateenclosing marks (parentheses,square brackets etc.). Whenever necessary, configuration symbols and ring size designators etc. may be included, to make the notation more specific. Example: Gala-6Glca-PFrufor GalaGGlcapFruffor raffinose The following examples show all three representations of the same structure:
(a)extended form P-D-Galp(1+4)-P-~-GlcpNAc-(1+2)-a-~-Manp(1+ 3
t
1
c~-L-Fuc~ (b) condensed form in two lines
Gal(PI-4)GlcNAc(~I -2)Man(al-
I
Fuc(a1-3) or in one line Gal(~1-4)[Fuc(crl-3)]GlcNAc(P1-2)Man(crl-
(c) short form GalP-4(Fuca-3)GlcNAcp-2Manaor Galp4(Fuca3)GlcNAcp2Manaor Galp4GlcNAcp2Mana-
I
Fuca3
NOMENCLATURE OF CARBOHYDRATES
I63
This last version is recommended as the most explicit representation of branching using the short form.
Note. These representations do not follow the recommendations for choice of main chain given in 2-Carb-37.3. Such deviations are common in depicting series of naturally occurring oligosaccharides where it is desirable to show homomorphic relationships.
2-Carb-39.Polysaccharides * 2-Carb-39.1. Names for homopolysaccharides A general term for a polysaccharide (glycan) composed of a single type of monosaccharide residue is obtained by replacing the ending ‘-ose’ of the sugar name by ‘-an’.
Note. Examples of established usage of the ‘-an’ending are: xylan for polymers of xylose, mannan for polymers of mannose, and galactan for polymers of galactose. Cellulose and starch are both glucans, as they are composed of glucose residues. 2-Carb-39.2. Designation of configuration of residues When the configurational series of the monomer residues is known, D- or L- may be included as a prefix to the name. Examples:
A D-glucan (nigeran) [5)-a-~-Araf-(l+5)-a-~-Araf-( 1 +5)-a-~-Araf-(1+5)-a-~-Araf-(l+In 3 3
t
1 a-L-Araf
7 1 a-L-Araf
An L-arabinan (more specifically an a-L-arabinan)
*
This is a modified version of the 1980recommendations on polysaccharide nomenclature [71.
NOMENCLATURE OF CARBOHYDRATES
164
2-Carb-39.3. Designation of linkage When the major linkage in a hornopolysaccharide is known, it may be indicated in the name. The linkage designation shows the carbon atoms involved in the glycosidic bonds. When specificsugars are designated, notation for glycosidic linkages should precede the symbols designating the configuration of the sugar; thus, (1+4)-&-D-glucan. Examples: HO -
*oH2cp7 1
HO
0-
-H
(2+1 )-P-D-Fructofuranan (inulin has this structure, with a terminal a-D-glucopyranosyl group) [4)-a-D-Glcp(l +In (1-)4)-a-D-Glucopyranan (arnylose)
Note. When the linkage between monosaccharideunits is non-glycosidic(as in the phosphate derivative shown below), use of the glycan terminology is inappropriate; other methods of polymer nomenclature should be employed [20]. -
Hi
0 1
Poly[(P-o-ribofuranosyl-5-Oyl)(1-deoxy-D-ribitol-1- C,5-Odiyl)(oxidophosphoryl)]
[5)-P-o-Ribf-(l-l )-~-Rib-ol-5-P-(O+]~
Such structures do not conform to the original strict definition of ‘polysaccharide’ but are generally classified as polysaccharides in current practice.
2-Carb-39.4. Naming of newly discovered polysaccharides Names assigned to newly discovered polysaccharides should end in ‘-an’.
NOMENCLATURE OF CARBOHYDRATES
165
Examples:
Pustulan (a glucan from the lichen Umbilicariapustulata)
L [3)-~-D-Glcp-(l+4)-P-D-GlcpA-(l+4)-~-D-Glcp-(l+4)-a-~-Rhap(1 -+In Gellan (a bacterial polysaccharide originally designated S-60)
Note.The name ending in '-an' refers to the unsubstituted polysaccharide. Thus xylan occurs in nature in unacetylated and partially acetylated forms. Xylan designates the unacetylated material, and xylan acetate an acetylated derivative. Well established names such as cellulose, starch, inulin, chitin, amylose and amylopectin are retained. 'Carrageenan' and 'laminaran' are now often used rather than the older names ending in '-in'.
2-Carb-39.5. Uronic acid derivatives. A polysaccharide (glycan) composed entirely of glycuronic acid residues is named by replacing '-ic acid' by '-an'. The generic name for this group of polysaccharides is 'glycuronan'. Example:
(1+4)-a-~-gaIacturonan (pectin component)
Note. The term glycuronan is used instead of 'polyuronide'; the latter term is incorrect.
NOMENCLATURE OF CARBOHYDRATES
166
2-Carb-39.6.Amino sugar derivatives A polysaccharide composed entirely of amino sugar residues is named by appropriate modification of the systematic amino sugar name. Example: 1 +In [.Q)-P-D-GlCpNAc(
(1 +4)-2-acetarnido-2-deoxy-~-~-glucan(chitin)
2-Carb-39.7. Polysaccharides composed of more than one kind of residue A heteropolysaccharide(heteroglycan) is a polymer containing two or more kinds of sugar (glycose) or modified sugar (e.g. aminodeoxyglycose or glycuronic acid) residue. When the polysaccharide has a principal chain (‘backbone’) composed of only one type of sugar residue, this residue should be cited last (as a ‘glycan’ term), and the other types of residue cited as ‘glyco-’ prefixes in alphabetical order. However, when no single type of sugar residue constitutes the principal chain, all sugar residues should be cited alphabetically as ‘glyco-’ prefixes, and the name should terminate with the suffix ‘-glycan’. Examples: a-D-Galp 1
5 6
[4)-P-D-Manp(1+4)-P-~-Manp(l+]n A o-galacto-D-rnannan (guaran) Note. A less branched D-galacto-o-mannancould be shown in the short form as: Gala-6
I
Gala-6
I
[4ManP-]rPManP-[4Manp-]r~~an~-.
167
NOMENCLATURE OF CARBOHYDRATES
[4)-P-D-GICp(1+4)-P-D-Glcp( 1+In 3
7 1
P-D-Manp( 1-+4)-P-~-GlcpA-( 1+e)-a-D-ManpGAc 6 4
\/
CH3CC02-
Xanthan 2-Carb-39.8. Substituted residues When substitution occurs in a polysaccharide (glycan), each type of substitutent is cited in the name at an appropriate position (in alphabetical order). Examples:
1
H
OH 0 HO
OMe
OH
2,3-Di-0acetyl-6-Otritylamylose [4)-P-D-GlCpA-( 1+3)-P-D-GlcpNAc-(1+In (2-Acetarnido-2-deoxy-~-gluco)-~-glucuronoglycan (hyaluronicacid or hyaluronan) 2-Carb-39.9. Glycoproteins, glycopeptides and peptidoglycans Polymers containing covalently bound monosaccharide and amino-acid residues are termed glycoproteins, glycopeptides or peptidoglycans. It is not possible to give
NOMENCLATURE OF CARBOHYDRATES
168
precise distinctions between these terms. In general, glycoproteins are conjugated proteins containing either oligosaccharide groups or polysaccharide groups having a fairly low relative molecular mass. Proteoglycans are proteins linked to polysaccharides of high molecular mass. Peptidoglycans consist of polysaccharide chains covalently linked to peptide chains. The nomenclature of these compounds is discussed in [ 111. Synthetically produced or modified carbohydrate-proteinconjugates are sometimes referred to as neoglycoproteins. The nomenclature for the carbohydrate-containing substituents in such structures is analogous to sequential oligosaccharide nomenclature (2-Carb-37.2) Examples:
Poly-[(3,6-Di-3methyl-P-o-glucopyranosyl)-( 1+4)-(2,3-di- Omethyla-L-rhamnopyranosy1)-(1+2)-(3-Omethyl-a-~-rhamnopyranosyloxy)(1-0+9)-nonanoyl-( 1+N]-protein
([~-~-Glcp3,6Men-(l-+4)cr-~-Rhap2,3Mez-(l+2)-a-~-Rhap3Me-(l-0+9)nonanoyl-(1+NIrprotein}
r
I
*03wo HO
HO Me0
OH
OMe
OMe
Poly-[(3,6-Di-Omethyl-~-~-glucopyranosyl)-( 1+4)-(2,3-di-Omethyla-L-rhamnopyranosy1)-(1+2)-(3-Omethyl-a-~-rhamnopyranosyloxy)-(1-&4')(3-phenylpropanoyl)-(1+NLYS]-protein
NOMENCLATURE OF CARBOHYDRATES
169
References 1. IUPAC Commission on the Nomenclature of Organic Chemistry (CNOC) and IUPACIUB Commission on Biochemical Nomenclature (CBN), Tentative rules for carbohydrate nomenclature, Part I. 1969, Biochem J., 125,673-695 (1971); Biochemistry, 10,3983-4004 (1971); Biochim. Biophys. Acra, 244,223-302 (1971); Eur. J. Biochem., 21,455-477 (1971) and 25,4 (1972); J. Biof. Chem., 247,613-635 (1972);ref.2, pp.127-148.
2. InternationalUnion of Biochemistry and Molecular Biology, ‘Biochemical Nomenclature and Related Documents’, Portland Press, London (1992). 3. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Conformational nomenclature for five- and six-membered ring forms of monosaccharides and their derivatives (Recommendations 1980), Eur.J.Biochem. 111, 295-298 (1980); Arch. Biochem. Biophys., 207,469-472 (198 1);Pure Appl. Chem.,53,1901-1905 (198 1); ref. 2, pp. 158-161. 4. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Nomenclature of branched-chain monosaccharides (Recornmendations 1980), Eur. J. Biochem., 119, 5-8 (1981); corrections: Eur. J. Biochem., 125,1(1982);PureAppf. Chem.,54,211-215 (1982); ref.2, pp. 165-168. 5. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Nomenclature of unsaturated monosaccharides(Recommendations 1980). Eur. J. Biochem., 119,l-3 (1981); corrections: Eur. J. Biochem., 125,l (1982); Pure Appl. Chem., 54,207-210 (1982); ref.2, pp. 162-164. 6. IUPAC-IUB Joint Commission on Biochemical lrjomenclature (JCBN), Abbreviated terminology of oligosaccharide chains (Recommendations 1980), J. Biof. Chem., 257, 3347-3351 (1982); Eur. J. Biochem., 126,433-437 (1982);PureAppl.Chem.,54,1517-1522 (1982); Arch. Biochem. Biophys., 220,325-329 (1983); ref. 2, pp. 169-173. 7. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Polysaccharide nomenclature(Recommendations1980),Eur. J. Biochem., 126,439-441 (1982); Pure Appl. Chem., 54, 1523-1526 (1982); J. Biol. Chem., 257, 3352-3354 (1982); Arch. Biochem. Biophys., 220,330-332 (1983); ref. 2, pp. 174-176.
8. IUPAC-IUB Commission on Biochemical Nomenclature (CBN), Nomenclatureof cyclitols (Recommendations 1973), Biochem. J., 153, 23-31 (1976); Eur. J. Biochem., 57, 1-7 (1975); Pure Appf. Chem, 37,283-297 (1974); ref. 2, pp.149-155. 9. Nomenclature Committee of IUB (NC-IUB), Numbering of atoms in myo-inositol (Recommendations 1988). Biochem. J., 258, 1-2 (1989); Eur. J. Biochem., 180,485-486 (1989); ref.2, pp. 156-157. 10. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Symbols for specifying the conformation of polysaccharide chains (Recommendations 198l), Eur. J. Biochem, 131,5-7, (1983); PureAppl. Chem., 55, 1269-1272 (1983); ref. 2, pp. 177-179. 1 1. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Nomenclature of glycoproteins, glycopeptides and peptidoglycans, Eur. J. Biochem., 159, 1-6 (1986); GlycoconjugateJ., 3,123-124(1986); J. Biol. Chem., 262,13-18 (1987); PureAppl. Chem., 60, 1389-1394 (1988); Royal Society of Chemistry Specialist Periodical Report, ‘Amino Acids and Peptides’, vol. 21, p. 329 (1990); ref. 2, pp. 84-89.
170
NOMENCLATURE OF CARBOHYDRATES
12. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), Nomenclature of glycolipids, in preparation. 13. IUPAC Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F and H, 1979 Edition, Pergamon Press, Oxford, U.K. Sections E and Fare reprinted in ref. 2, pp. 1-18 and 19-26,respectively. 14. Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993, Blackwell Scientific Publications, Oxford (1993).
15. This text is largely based on an essay entitled ‘Development of Carbohydrate Nomenclature’ by D. Horton, included in ‘The Terminology of Biotechnology: A Multidisciplinary Problem’ (ed. K.L. Loening, Springer-Verlag, Berlin and Heidelberg, 1990). 16. E. Fischer, Ber., 23,2114 (1890). 17. Rules of carbohydrate nomenclature (1948), Chem. Eng. News, 26, 1623 (1948). 18. Rules of carbohydrate nomenclature (1952), J. Chem. Soc., 5108 (1952); Chem. Eng. News,31, 1776 (1956).
19. Rules of carbohydrate nomenclature (1963). J. Org. Chem., 28,281 (1963). 20. IUPAC Commission on Macromolecular Nomenclature, Nomenclature of regular single-strand organic polymers (Recommendations 1975), Pure Appl. Chem., 48, 373-385 (1 976); ‘Compendium of Macromolecular Nomenclature’, Blackwell Scientific Publications, Oxford, p.91 (1991).
21. IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), The nomenclature of lipids (Recommendations 1976),Eur. J. Biochem., 79,11-21 (1977);Hoppe-Seyler’s Z. Physiol. Chem., 358, 617-631 (1977);Lipids, 12,455-468(1977);Mol. Cell. Biochem., 17,157-171 (1977); Chem. fhys. Lipids, 21, 159-173 (1978);J. LipidRes., 19, 114-40728 (1978); Biochem. J., 171.21-35 (1978); ref. 2, pp. 180-191. 22. D. Cremer and J.A. Pople, J. Am. Chem. Soc., 97, 1354-1358 (1975): J.C.A. Boeyens, J. Cryst. Mol. Struct, 8, 317-320 (1978); P. KOII, H.-G. John, and J. Kopf, Liebigs Ann. Chem., 626-638 (1982). 23. IUB Nomenclature Committee, ‘Enzyme Nomenclature’, Academic Press, Orlando, Florida (1992). 24. IUPAC-IUB Commission on Biochemical Nomenclature (CBN), Nomenclature of phosphorus-containing compounds of biochemical importance (Recommendations 1976), Hoppe-Seylers Z. Physiol. Chem., 358,599-616 (1977); Eur. J. Biochem., 79, 1-9 (1977); Proc. Natl. Acad. Sci. USA, 74,2222-2230 (1977); Biochem. J., 171,l-19 (1978); ref. 2. pp. 256-265. 25. IUPAC Commission on Nomenclature of Organic Chemistry, Revised nomenclature for radicals, ions, radical ions and related species (Recommendations 1993),Pure Appl. Chem., 65,1357-1455(1993). 26. IUPAC Nomenclature of Organic Chemistry, Section F, revised version in preparation.
NOMENCLATURE OF CARBOHYDRATES
171
27. IUPAC Commission on Nomenclatureof Organic Chemistry, Revision of the extended Hantzsch-Widman system of nomenclature for heteromonocycles, Pure Appf. Chem., 55, 409-416 (1983).
NOMENCLATURE OF CARBOHYDRATES
112
APPENDIX Trivial Names for Carbohydratesand Derivatives with their Systematic Equivalents and Symbols (non-limiting list) (a) parent monosaccharides Allose (All)
allo-Hexose
Altrose (Ah)
altro-Hexose
Arabinose (Ara)
arabino-Pentose
Erythrose
erythro-Tetrose
Erythrulose
glycereTetrulose
Fructose (Fru)
arabinsHex-2-ulose
D-Fucitol (D-FUC-01)
6-Deoxy~-galactitol
L-Fucitol (L-FUC-01)
1-Deoxy-D-galactitol
Fucosamine (FucN)
2-Amino-2,6-dideoxygalactose
Fucose (Fuc)
6-Deoxygalactose
Galactosamine (GalN)
2-Amino-2-deoxygalactose
D-Galactosaminitol (GalN-ol)
2-Amino-2-deoxy~-galactitol
Galactose (Gal)
galacto-Hexose
Glucosamine (GlcN)
2-Amino-2-deoxyglucose
Glucosaminitol (GlcN-01)
2-Amino-2-deoxyglucitol
Glucose (Glc)
gluco-Hexose
Glyceraldehyde
2,3-Dihydroxypropanal
Glycerol (Gro)
Propane-l,2,3-triol
Glycerone (1,3-dihydroxyacetone)
1,3-Dihydroxypropanone
Gulose (Gul)
gulo-Hexose
ldose (Ido)
ido-Hexose
Lyxose (Lyx)
lyxePentose
Mannosamine (ManN)
2-Amino-2-deoxymannose
Mannose (Man)
manneHexose
Psicose (Psi)
ribo-Hex-2-ulose
NOMENCLATURE OF CARBOHYDRATES
Quinovose (Qui)
6-Deoxyglucose
Quinovosamine
2-Amino-2,6-dideoxyglucose
Rhamnitol (Rha-ol)
1-Deoxymannitol
Rhamnosamine(RhaN)
2-Amino-2,6-dideoxymannose
Rhamnose (Rha)
6-Deoxymannose
Ribose (Rib)
ribePentose
Ribulose (Rul)
erythro-Pent-2-ulose
Sorbose (Sor)
xybHex-2-ulose
Tagatose (Tag)
lyxeHex-2-ulose
Talose (Tal)
tale Hexose
Tartaric acid
Erythraricnhrearic acid
Threose
threeTetrose
Xylose (Xyl)
xylePentose
Xylulose (Xul)
three pent-Pulose
(b) common trivial names Abequose (Abe)
3,6-Dideoxy-~-xylehexose
Amicetose
2,3,6-Trideoxy-~-etythro-hexose
Amylose
(1+4)-a-~-Glucopyranan
Apiose (Api)
3-C(Hydroxymethy1)-glycero-tetrose
Arcanose
2,6-Dideoxy-3-Gmethyl-3-Omethylx y b hexose
Ascarylose
3,6-Dideoxy-~-arabinehexose
Ascorbic acid
~-threo-Hex-2-enono-l ,Cladone
Boivinose
2,6-D ideoxy-D-gulose
Cellobiose
p-D-Glucopyranosyl-(1+4)-~-glucose
Cellotriose
P-D-Glucopyranosyl-(1+4)-P-oglucopyranosyl-(1+4)-~-glucose
Chacotriose
a-L-Rhamnopyranosyl-(1+2)[a-L-rhamnopyranosyl-(1-+4)1-~-glucose
Chalcose
4,6-Dideoxy-3-0methyl-~-xylehexose
Cladinose
2,6-Dideoxy-3-Grnethyl-3-Qmethyl~-ribibo-hexose
173
174
NOMENCLATURE OF CARBOHYDRATES
Colitose
3,6-Dideoxy-~-xyle hexose
Cymarose
6-Deoxy-3-Qmethyl-ribehexose
2-Deoxyribose (dRib)
2-Deoxy-eryfbrepentose
2-Deoxyglucose (2dGlc)
2-Deoxy-arabinehexose
Diginose
2,6-Dideoxy-3-0methyl-/yxehexose
Digitalose
6-Deoxy-3-Qmethyl-D-galactose
Digitoxose
2,6-Dideoxy-~-ribehexose
Evalose
6-Deoxy-3-Cmethyl-D-mannose
Evernitrose
2,3,6-Trideoxy-3-Gmethyl-COrnethyl3-nitro-L-arabinehexose
Gentianose
P-D- Fruc t of u ranosyl
Gentiobiose
P-D-Glucopyranosyl-(1+6)-D-glUCOSe
Hamamelose
2-C(Hydroxymethyl)-~-ribose
lnulin
(2+1)-P-D-Fructofuranan
lsolevoglucosenone
P-D-glucopyranosyl(1+6)-a-~-glucopyranoside
1,8Anhydro-2,3-dideoxy-f3-D-g/ycer5 hex-2-enopyranos-4-ulose
lsomaltose
a-D-Glucopyranosyl-(1+6)-~-glucose
lsomaltotriose
a-D-Glucopyranosyl-(1+6)a-o-glucopyranosyl-(1+6)-o-glucose
lsopanose
a-o-Glucopyranosyl-(1+4)[a-o-glucopyranosyl-(1+6)]-D-glUCOSe
Kojibiose
a-o-Glucopyranosyl-( 1+2)-D-glucose
Lactose (Lac)
P-D-Galactopyranosyl-(1+4)-~-glucose
Lactosamine (LacN)
P-D-Galactopyranosyl-(1 +4)-o-glucosamine
Lactosediamine(LacdiN)
2-Amino-2-deoxy-~-~-galactopyranosyl(1+4)-~-glucosarnine
Laminarabiose
P-o-Glucopyranosyl-(1+3)-~-glucose
Levoglucosan
1,6-Anhydro-P-~-glucopyranose
Levoglucosenone
1,6-Anhydro-3,4-dideoxy-P-~-g/ycere hex-3-enopyranos-2-ulose
Maltose
a-D-Glucopyranosyl-(1-+4)-~-glucose
Manninotriose
a-D-Galactopyranosyl-(1+6)a-D-galactopyranosyl-(1+6)-D-glUCOSe
175
NOMENCLATURE OF CARBOHYDRATES
Melezitose
a-D-Glucopyranosyl-(I+3)0-D-fructofuranosyl a-D-glucopyranoside
Melibiose
a-D-Galactopyranosyl-(1+6)-D-glUCOSe
Muramic acid (Mur)
2-Amino-3-O[(R)- 1-carboxyethyl]-2-deoxyD-glucose
Mycarose
2,6-Dideoxy-3- Cmethy1-L-ribehexose
Mycinose
6-Deoxy-2,3-di-Omethyl-~-allose
Neuraminic acid (Neu)
5-Amino-3,5-dideoxy-~-glycef@~-galactc+ non-2-ulosonicacid
Nigerose
a-D-Glucopyranosyl-(1-+3)-~-glucose
Nojirimycin
5-Amino-5-deoxy-~-glucopyranose
Noviose
6-Deoxy-5-Gmethyl-4-OmethylL- lyxehexose
Oleandrose
2,6-Dideoxy-3-Omethyl-~-arabinehexose
Panose
a-D-Glucopyranosyl-(1+6)a-o-glucopyranosyl-(1+4)-~-glucose
Paratose
3,6-Dideoxy-D-ribehexose
Planteose
a-D-Galactopyranosyl-(1+6)P-o-fructofuranosyl a-D-glucopyranoside
Prirneverose
P-o-Xylopyranosyl-(1+6)-~-glucose
Raffinose
p-D-F r uc t of u ran05 y 1
a-o-galactopyranosyl-
(1+6)-a-~-glucopyranoside
Rhodinose
2,3,6-Trideoxy-~-threehexose
Rutinose
a-L-Rhamnopyranosyl-(1+6)-D-glUCOSe
Sarmentose
2,6-Dideoxy9-Omethyl-~-xy/@hexose
Sedoheptulose
~-altf@Hept-2-ulose
Sedoheptulosan
2,7-Anhydro-P-~-alfrehept-2-ulopyranose
Solatriose
a-L-Rhamnopyranosyl-(1+2)[p-o-glucopyranosyl-(1+3)]-~-galactose
Sophorose
P-D-Glucopyranosyl-(1+2)-o-glucose
Stachyose
p-D- F ruct of u ranos yl
Streptose
5-Deoxy-3- Cformyl-L-lyxose
a-o-galactopyranosyl(1+6)-a-D-galaCtOpyranOSyl(1+6)-a-~-glucopyranoside
176
NOMENCLATURE OF CARBOHYDRATES
Sucrose (saccharose)
0-D-Fructofuranosyla-o-glucopyranoside
a,a-Trehalose
ff-D-Glucopyranosyla-o-glucopyranoside
Trehalosamine
2-Amino-2-deoxy-a-~-glucopyranosyl a-D-glucopyranoside
Turanose
a-D-Glucopyranosyl-(1 +3)-D-f ructose
Tyvelose (Tyv)
3,6-Dideoxy-~-arabinehexose
Umbelliferose
p-D-Fructof uran0 s yI
a-D-galactopyranosyl(1 +2)-a-~-gaIactopyranoside
(c) trivial names formed by modification of non-standardmonosaccharide parent names Acosamine
3-Amino-2,3,6-trideoxy-~-xy/ehexose
Bacillosamine
2,4-Diamino-2,4,6-trideoxy-~-glucose
Daunosamine
3-Amino-2,3,6-trideoxy-~-/yx~hexose
Desosamine
3,4,6-Trideoxy-3-dimethylaminoD-xylehexose
Forosamine
2,3,4,6-Tetradeoxy-4-dimethylaminoo-erythrehexose
Garosamine
3-Deoxy-4-Cmethyl-3-methylaminoL-arabinose
Kanosamine
3-Amino-3-deoxy-~-glucose
Kansosamine
4,6-Dideoxy-3-Gmethyl-2-OmethylL-mannose
Mycaminose
3,6-Dideoxy-3-dimethylamino-~-glucose
M ycosamine
3-Amino-3,6-dideoxy-~-mannose
Perosamine
4-Amino-4,6-dideoxy-~-mannose
Pneumosamine
2-Amino-2,6-dideoxy-o-talose
Purpurosamine C
2,6-Diamino-2,3,4,6-tetradeoxyD-erythrehexose
Rhodosamine
2,3,6-Trideoxy-3-dimethylamino-/yxehexose
Glossary of Glycose-based Terms Standard forms [Common biochemical usage] Class
Amino sugaf (usually as acetamido (N-acetyl) derivative)
Uronic acidb (Ironate
Ulosonic acid u10s0nare
The sialic acid familyb
Glycose
Aminodeoxyglycose
Glycuronic acid
Glyculosonic acid
Neuraminic acid
Glycuronate
Glyculosonate
Sialic acid
[Glycosamine] Glycosyl
GIycoside
Aminodeoxyglycosyl
Glyculosylonare
Aminodeoxyglycoside
Glycosiduronicacid
Glyculosidonicacid
[Neuraminoside]
Glycosiduronate
Glyculosidonare
[Sialoside]
GIyculosidonase
[Neuraminidase]
[Glycosaminidase] Glycosyltransferase
Glyculosylonicacid
Glycosyluronate [GIycuronosyl]
GIycosidase Aminodeoxyglycosidase (Glycoside hydrolase)
QNOP
Glycosyluronic acid
[Glycosaminyl]
[Glycosaminide]
0
[Ketoglyconicacid]
[Glycuronide] Glycosiduronase [Glycuronidase]
[Sialidase]
Aminodeoxyglycosyltferase Glycosyluronatetransferase Glyculosylonatetransferase [Neuraminosyltransferase] [Glycosaminyltransferase]
[Glycuronosyltransferase]
[Sialosyltransferase]
f h e biochemical usage is widely established in the literature. ?he biochemical usage implies the parents ‘glycuronose’, ‘sialose’, and ‘neuraminose’. “Neuraminyl’ and ‘sialyl’ have been used, but are likely to be interpreted as referring to acyl groups; the t e r n given are more consistent with the terms used for glycosides
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ADVANCES IN CARBOHYDRATE CHEMISTRY AND BIOCHEMISTRY. VOL. 52
THIOCLYCOSIDES AS GLYCOSYL DONORS IN OLIGOSACCHARIDE SYNTHESIS
BY PER J. GAREGG Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden I. General Introduction: Glycosidation Methods for Oligosaccharide Synthesis . . . . . . . . . . 178 . . . . . . . . . . . . . . . . .. . . , . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . 181 1. From Acylated Aldoses by Reaction with a Thiol in the Presence of Lewis Acid , . . . . 181 2. From Acylated Glycosyl Halides by Reaction with Thiolate Anion . . . . . . . . . . . . . . . . . 181 181 3. From Glycosyl Halides Via Thiourea Intermediates . . . . . . . . 4. From Dithioacetals by Partial Hydrolysis . .. . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . 181 5. From 1-Thioaldose Derivatives by Reaction with Aryldiazonium Salts . . . . . . . . . . . . . 183 183 6 . From Glycosyl Xanthates by Decomposition . . . . . . . . 7. From Glycosyl Thiocyanates by Reaction with 183 183 8. From I-Thiols by Radical Addition to Alkenes 9. Acetylated Glycosyl Piperidine Carbodithioates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 111. Conversion of Thioglycosides Into Other Glycosyl Donors . . . . . . . . . . . . . . . . . . . . , . . . . . 183 184 IV. In situ Generation of Glycos 185 V. Direct Use of Thioglyosides 185 2. Stereoselectivity . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189 3. Transfer of the “Armed-Disarmed’ Concept to Thioglycoside Glycosylation Reactions . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . , . . . . . . . . . . . . . . . . . . , . . . . , , . . . 189 VI. Thioglycosides in Block Synthesis of Oligosaccharides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 VII. Thioglycosides as Glycosyl Acceptors in Oligosaccharide Synthesis . . .. . . . . . . . . . . 197 VIII. Glycosyl Sulfoxides, Sulfones, and Selenoglycosides as Glycosyl Donors . . . . . . . . . 198 IX. Conclusions . . . . . . . . . . ... . .. ...... ... 199 References . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . , . , , . . . . . . . . . . . . . . , . . . . . . . . , , . . . . 199 11. Preparation of Thioglycosides
.
I
.
.
I. GENERAL INTRODUCTION: GLYC~SIDATION METHODS FOR OLIGOSACCHARIDE SYNTHESIS The presence and biological importance of oligosaccharide structures, usually as components of glycolipids and glycoproteins, in bacterial capsular and cellwall polysaccharides, in mammalian cell membranes, in cytoplasm, and in extracellular fluids, are now well documented. They are important constituents in 0096-5332197 $25.00
179
Copyright D 1997 by Academic Press. All rights of reproduction in any form reserved.
180
PER J. GAREGG
such biological macromolecules as immunoglobulins, enzymes, and transport proteins. To mention just some of their many vital biological functions, they participate in cell recognition and adhesion, in regulatory processes, in inflammatory processes, in blood coagulation, and in immunological protection, and they can serve as lubricants. The need for access to oligosaccharides and conjugates for biomedical research has posed a formidable challenge in organic synthesis. Great strides have been made in this area, parallel to the progress made by biologists. From a modest beginning of synthesis of disaccharides, usually in low yields, organic chemists are now able to make large oligosaccharides by block synthesis. The largest one thus far made by unambiguous chemical synthesis is, to the author's knowledge, that described by Ogawa et al.' of a pentacosasaccharide corresponding to the glycan part of a glycosyl ceramide from rabbit erythrocyte membrane. Oligosaccharide synthesis has been covered in Advances in Carbohydrate Chemistry and Biochemistry' and in many review article^.^-'^ This chapter treats specifically the development of the use of thioglycosides in oligosaccharide synthesis. Of the many methods described for glycoside synthesis, those predominantly used in current oligosaccharide synthesis, in which the glycosyl donor has 0- or N - functionality at C-2 (that is, excluding 2-deoxyglycosides), are the following: In the Koenigs-Knorr method and in the Helferich or Zemple'n modifications thereof, a glycosyl halide (bromide or chloride; iodides can be produced in siru by the addition of tetraalkylammonium iodide) is allowed to react with a hydroxylic compound in the presence of a heavy-metal promoter such as silver oxide, carbonate, perchlorate, or mercuric bromide and/or oxide,l9-'' or by silver trifluoromethanesulfonate2' (AgOTf). Related to this is the use of glycosyl fluoride donors,23which normally are prepared from thioglyc~sides.~~ In the trichloroacetimidute method,18 which is a modification of the earlier imidate m e t h ~ d , ~an. ' otherwise-protected ~ pyranose derivative with a free 1-OH is treated with trichloroacetamide under basic conditions to give first, under kinetic control, a p-trichloroacetimidate (in the D series), which then anomenzes to produce the thermodynamically more stable (Y anomer. Each of these, under promotion by a Lewis acid, such as boron trifluoride etherate, gives, in the presence of a nonparticipating group in the 2-position of the glycosyl donor and in the presence of a hydroxylic glycosyl acceptor, glycosides with anomeric configuration opposite to that of the glycosyl donor." In the presence of a participating 2-substituent (acyl), a 1,2-trans glycoside is formed.Is In the halide-assisted method,2s a glycosyl halide (normally bromide) with a nonparticipating 2-substituent and with the thermodynamically more stable axial orientation at C-1 is treated with an excess of the corresponding halide anion by the addition of a soluble tetraalkylammonium salt. This sets up an equilibrium between the axial and the (much less stable) equatorial glycosyl halide. The lat-
THIOGLYCOSIDES AS GLYCOSYL DONORS
181
ter reacts faster than its axial counterpart. Provided that this reaction and the equilibration one are faster than the reaction of the axial halide, the predominant product will have the axial configuration at C-1. This reaction generally is limited to reactive hydroxylic acceptors. In the 4-pentenyl glycosidation a 4-pentenyl glycoside is treated with a halonium ion. This produces a 2-halomethyltetrahydrofuran and an intermediate glycosyl cation, which, in the presence of a hydroxylic glycosyl acceptor produces a glycosidic bond. In a modification of this method, a 4-pentenoic as a leaving group at C- 1. ester group is An emerging method is the use of glycals in oligosaccharide ~ynthesis.'~ These methods are summarized in Scheme 1. Methods based on the use of thioglycosides are covered later in this chapter. 11. PREPARATION OF THIOGLYCOSIDES
A great variety of methods for the preparation of alkyl and aryl l-thioglycosides of aldoses have been d e ~ c r i b e d ~ ~ . ~ ' : 1. From Acylated Aldoses by Reaction with a Thiol in the Presence of Lewis A ~ i d ~ ~ - ~ ~ Fully acetylated hexopyranoses react with thiols in the presence of Lewis acids, such as BF,.Et20.32,33The reaction is faster with 1,2-truns acetates than with the corresponding 1,2-cis ones and 1,2-truns products predominate. Alkyl, alkenyl, and aryl thioglycosides are produced by this method. Variations on this method include the use of trimethyl~ilyl~~ or stannyl derivative^^^ of the thiols.
2. From Acylated Glycosyl Halides by Reaction with Thiolate
In this classic4' and general method, an acylated glycosyl halide reacts with a thiolate anion to produce a 1-thioglycoside, usually with 1,2-trans configuration. With alkyl thiolates, re-acylation is normally required following this treatment. 3. From Glycosyl Halides via Thiourea Intermediatesa An acylated glycosyl halide, such as a 2,3,4,6-tetra-O-acetyl derivative, is treated with thiourea. The resulting pseudothiouronium salt is hydrolyzed with aqueous potassium carbonate to give the 2,3,4,6-tetra-O-acetyl-l-thio-P-Dglucopyranose,48 which then is alkylated. 4. From Dithioacetals by Partial H y d r o l y ~ i s ~ ~ ~ ~ ~ Partial hydrolysis of dithioacetals has been found useful for the preparation of anomers not obtained by the foregoing methods and also for preparation of furanosidic 1-thioglycosides.
a
Ag+or Hg2+ *OR
BnO
ROH
*
BnO
X = Bror CI
AaCor
x*
HC
v
ROH
Rr
T
R
R = Me or Ph
Intermediatecation R = Me or Ph
KOENIGS-KNORRIHELFERICHIZEMPLEN GLYCOSYLATION
OR BnO
OR
TRICHLOROACETIMIDATE GLYCOSYLATION
1 *OR
* fast
RoH
1
RoH
OR
En0
HALIDE ASSISTED GLYCOSYLATION ROH
NIS NIS-TfOH NIS-Et3SiOTf 4-PENTENYL GLYCOSIDATION
SCHEME1
+
5
0
THIOGLYCOSIDES AS GLYCOSYL DONORS
183
5. From l-Thioaldose Derivatives by Reaction with Aryldiazonium Salt~~'9~' This preparation, specifically of acylated aryl thioglycosides, is carried out by reaction of, for instance, a 2,3,4,6-tetra-O-acetyI- 1-thio-P-D-glucopyranose with a diazonium salt, followed by thermal decomposition of the intermediate diazo product.
6. From Glycosyl Xanthates by Decomposition Acylated glycosyl xanthates are made by treating acylated glycopyranosyl halides with a potassium alkyl (or benzyl) xanthate",sl in solution or under phase-transfer conditions,s2 or from the reaction of benzylated 1-OH sugars by treatment with p-toluenesulfonyl chloride and potassium alkylxanthates, also under phase-transfer condition^.^^ The xanthates are readily decomposed to the corresponding l-thioglycosides by heating in solution or by thermal treatment in melt.
7. From Glycosyl Thiocyanates by Reaction with Grignard Reagents Acylated glycosyl thiocyanates are made by treatment of acylated glycopyranosy1 halides with potassium thi~cyanate.~'Reaction at -40" with a Grignard reagent affords alkyl or aryl l-thioglyc~sides.~~
8. From l-Thiols by Radical Addition to Alkenes Acetylated 1-thioaldoses react with alkenes in the presence of azobis(isobutyronitrile) (AIBN) to give acylated alkyl I -thioglyco~ides.~~
9. Acetylated Glycosyl Piperidine Carbodithioates These compounds are made by allowing the salt made from piperidine and sodium hydride to react with CS, and then with an acetylated glycosyl bromide.s6 111. CONVERSION OF THIOGLYCOSIDES INTO OTHER GLYCOSYL DONORS An attractive feature of thioglycosides as glycosyl donors in oligosaccharide synthesis is that they are readily converted into all of the other glycosyl donors outlined already in Section I. This is illustrated in Scheme 2. Thioglycosides are thus readily converted into glycosyl bromides. These can be used directly by reaction with a hydroxylic acceptor under p r o m ~ t i o n ' ~by - ~ Ag', ~ Hg2+, or tetraalkylammonium bromidez5 to give a glycosidic product. Alternatively, the bromide can be hydrolyzed to a 1-OH product, which is then converted into a trichloroacetimidate,I8 which is subsequently transformed into a glycosidic
PER J. GAREGG
184
C13CCN
f
Base
o-0-v"c~ci3 /
NBS
Thiophilic
O
X = Glycosyl donor. X = Br, F, SR, OC(NH)CC13, 0-4-pentenyl
HO-0 = ~ ~ y c o acceptor sy~
SCHEME 2
product under acid catalysis. The glycosyl bromide can also be converted into a 4-pentenyl glycoside, which becomes a glycosyl donor by promotion with an iodonium compound.26Finally, a thioglycoside can be converted into a glycosyl f l ~ o r i d e ? which ~ . ~ ~ under promotion24with SnCI,-AgCIO, or by' Cp,Hf(OTf),, reacts with a hydroxylic acceptor to give a glycosidic product. Because some of these alternative glycosyl donors can be used together with thioglycosidic ucceptors (Section VI), this gives considerable flexibility in oligosaccharide synthesis. The most direct route from a thioglycoside to an 0-glycoside is, however, by direct activation or by in situ conversion into an intermediate glycosyl bromide (Section IV).
Iv. I N SITU GENERATION OF GLYCOSYL HALIDES FROM THIOGLYCOSIDES Treatment of a thioglycoside with (Bu,N),CuBr, produces an intermediate glycosyl bromide, which, in the presence of a hydroxylic glycosyl acceptor and AgOTf,22ss0produces a glycosidic bond.57As shown in Scheme 3, the presence of a participating group in the 2-position of the thioglycoside gives a 1,2-truns glycoside, whereas a nonparticipating 2-substituent gives predominantly a 1,2cis g l y ~ o s i d e . ~ ~
THIOGLYCOSIDES AS GLYCOSYL DONORS
A AcO c
O
185
""a
aSMe
BnO
NPhth
OBn OBn
1, (Bu4N)&uBr4 2. AgOTf
Me+
A AcO c O a F + O B n
NPhth
=
3
0OBn B
n
OBn
OBn
BnO OBn 72%
84%
SCHEME 3
The thiophilic reagent dimethyl(methy1thio)sulfonium triflate59(DMTST) efficiently generates glycosyl cations from thioglycosides6' (Section V). In the presence of excess tetraalkylammonium bromide, the ol/P-equilibrium characteristic of the Lemieux halide-assisted reaction is set up (Section I). The equatorial halide will then react with a hydroxylic glycoside acceptor in a typically slow reaction leading, from a glycosyl donor with a nonparticipating 2-substituent, predominantly to a 1,2-cis glycoside as shown in Scheme 4.61
v. DIRECTUSE OF THIOGLYCOSIDES BY MEANS OF THIOPHILIC ACTIVATORS 1. Promoters
A report by Ferrier and co-workers sparked interest in the direct use of thioglycosides in glycosylation reactions.62Thus, phenyl 1 -thio-D-glucopyranosides were solvolyzed in the presence of Hg(OAc), in methanol to give the methyl glycosides having anomeric configuration opposite to that of the thioglycosides. More significantly, phenyl 2,3,4,6-tetra-O-benzyl-l-thio-~-~-glucopyranoside to give an areacted with 1,2:3,4-di-O-isopropylidene-a-~-galactopyrano~e (l-)-linked disaccharide in 54% yield. Following these observations, a range of different promoters was advocated and used in the construction of glycosidic bonds. They include: Cu(OTf), (ref. 63), Hg(OBe), (ref. 64), Hg(NO,), (ref. 65), Pd(ClO,), (refs. 66,67), NBS (Nbromosuccinimide) (ref. 68), PhHgOTf (ref. 69), and HgC1, (refs. 62,70). None of these, however, gave the consistently high yields sought for the block synthesis of oligosaccharides.
PER J. GAREGG
186
DMTST
BnO OBn
OBn
OMe Bu,N+W CH2Clp r.t. 1.5 weeks
BnBnO *'OMe OBn
83% In the absence of Eu,N'Er': r.t. 2 days, 50% a-linked and 30% 8-linked disaccharide
SCHEME4
Subsequently, Lonn demonstrated that methyl triflate is a most efficient thiophilic promoter for producing glycosyl cations, which readily react with hydroxylic glycoside acceptors to give glycosides and oligosaccharides.'-74 As expected, a participating group in the 2-position of the donor gave a 1,2-trans glycoside, whereas a nonparticipating group gave an a@ mixture as shown in Scheme 5. A higher proportion of 1,Z-cis glycosides was obtained in diethyl ether as solvent, probably caused by solvent participation at the anomeric center of the intermediate glycosyl cation.74 TABLE I Glycosyl Donors and Activators ~
Activator
SR'
Main Author(s)
Reference
MeOTf DMTST NOBF, MeSOTf, MeSBr TrCIO, (cat) PhSeOTf Me1 NIS-TfOH
SMe. SEt, SPh SMe, SEt, SPh SMe SMe, SEt, SPh SCN. (ROTr acceptor) SMe SPY SMe, SEt, SPh
IDCP
SEt
Lonn, 1984/85 Fiigedi, Garegg, 1986 Pozsgay, Jennings, 1987/88 Dasgupta, Garegg, 1988 Kochetkov ef al., 1989 Ogawa ef a/., 1988/89 Reddy ef a/., 1989 van Boom et al.. 1990 Konradsson et uf., 1990 Veeneman, van Boom ef al., 1990
71-74 60 76 71 78 79 80 81 82 83
Sinay et a/., 1990
84 85
Fiigedi et af.,1991
56
Ph
TBPA
SEt, SPh S
DMTST, AgOTf SnCl,, FeCI,
THIOGLYCOSIDES AS GLYCOSYL DONORS
d
187
d
R=Ac or Bz
SCHEME 5.-Direct
activation of thioglycosides
The concept for oligosaccharide synthesis arising from these observations was to synthesize an oligosaccharide acceptor block with one or several free OH groups. The other block would be a thioglycoside donor made by nonthioglycoside methodology. Condensation of the two would then produce a large oligosaccharide. This approach proved most useful in oligosaccharide synthesis. Early examples include the synthesis of part of the carbohydrate structural component of a glycoprotein isolated from fucosidosis patient^'^ and also of phytoelicitor oligosaccharides involved in the recognition and defense of the soybean plant against infections by Phytophthoi-a megasperma." The key steps of these syntheses are shown in Schemes 6 and 7. Methyl triflate has disadvantages. It is toxic, and in the presence of slowreacting glycosyl donors, it can give rise to methyl ethers in addition to glycosides. For these reasons, the subsequent investigations described an extensive search for alternatives. The major ones are outlined in Table I. Most of the new promoters used alkyl and aryl thioglycoside donors, but also glycosyl isothiocyanates (in conjunction with trityl ether acceptors), as well as S-pyridyl and 1-phenyl-1H-tetrazol5-yl thioglycosides and glycosyl 1-piperidinecarbodithioates.This is summarized in Table I. All of these promoters are electrophilic and activate the thioglycoside and the analogues just mentioned by producing intermediate sulfonium ions, which then give rise to glycosylating carbocationic intermediates. Of these various promoters, iodomethane should be used with extreme care because of its toxicity. Iodonium dicollidine perchlorate (IDCP) should be replaced by iodonium dicollidine triflate (IDCTf), which has similar reactivity and which does not require the use of AgClO, in its synthesis. MeOTf, DMTST, NIS-TfOH, and in particular PhSeOTf are all most efficient promoters that produce fast reactions. MeSOTf and MeSBr are slower reacting, but are easy and safe to make. Tris(4-bromophenyl)ammoniurnylhexachloroantimonate (TBPA) differs from the other promoters in that its cation is a radical, and as such produces radical cationic sulfonium ions as glycosylating species from thioglycosides.8sThe use of this promoter arose from earlier work on the electrochemical generation of S-glycosyl radical cations as glycosylating species.
188
PER J. GAREGG
AcO
0
1
OBn
NPhth
61Yo
AcO
P-D-Galp(l+ 4)
-
)3-D-GlcpNAc-(l-- 2)
\ a-D-Manp(1-
a-L-Fucp(1 ' ) 3 a-L-Fucp(1-3)
\ P-D-GlcpNAC-(+
2)
p-D-Galp(1-- 4) f SCHEME 6
f
a-D-Manp(1-
6
'
D-Man
3 y
THIOGLYCOSIDES AS GLYCOSYL DONORS
189
0
II
,OCCH,CI
, o* : zB 820
MeOTl
. OBZ
SCHEME 7
2. Stereoselectivity The presence of a participating group in the 2-position of the glycosyl donor, such as 0-acetyl, 0-benzoyl (in preference to O - a ~ e t y lor ~ ~N-phthaloyl , ensures the production of a 1,2-truns glycoside with excellent stereoselectivity.60In the presence of a nonparticipating group, such as 0-benzyl in the 2-position, the proportion of the 1,2-cis glycoside can be enhanced by the use of diethyl This is illustrated in the examples in Scheme 8. In acetonitrile as solvent, and with a nonparticipating 2-substituent in the glycosyl donor, 1,2-truns glycosides are formed as a result of solvent parti~ipation.~~ 3. Tkansfer of the “Armed-Disarmed” Concept to Thioglycoside Glycosylation Reactions
The “armed-disarmed’ concept was developed in connection with glycosylation reactions using 4-pentenyl glycosides as glycosyl donors.g0This means that hozh the donor and acceptor can be linked to activable 4-pentenyl groups. If the donor is activated (“armed”) by electron-donating groups, such as benzyl, and the acceptor is deactivated (“disarmed”) by electron-withdrawing groups, such as acetyl and benzoyl, selective activation of the donor is possible, producing a new oligosaccha-
190
PER J. GAREGG
&?O&SMe BzO
OBz Donor Acceptor denotes acceptor OH and yield of @-linked disaccharideobtained wiul linkage to that position Other hydroxyl groups were blocked 1,Z-cis
B
P
n En0
o
a
S
E
t
+
h
BnO
T
s SEt OpMEn
pHO h T? MeOTf
1 -3,
96% a p 6 7 1
Et20
OBn
OMe
L h n . 1987
DMTST
+
Me OMe
Et~01CH2C12
U-I
-3,0470
Garegg. Helland. 1993
SCHEME &-Stereoselectivity
ride, which subsequently can be activated under more vigorous conditions or longer reaction time to produce a new oligosaccharide with a second acceptor molecule. This concept can indeed be transferred to oligosaccharide syntheses using thioglycoside donors, as shown in Scheme 9.y’.92 A disadvantage of this concept is that it imposes restrictions on the protectinggroup strategy used in making the donor and acceptor and might lead to excessive protecting-group manipulating schemes to obtain the two components activated and deactivated, respectively. For this reason, serious attempts have been made to activate and deactivate at the anomeric center, so that this activation-deactivation would predominate over any activation or deactivation at other positions in the pyranoside (or furanoside) rings. Some attempts at this, using electronic activation-deactivation at the anomeric center, are s h o ~ nin~ ~ , ~ ~ Scheme 10. Thus, it seems that the concept of anomeric electronic activation-deactivation at the anomeric center taking precedence over “armed-disarmed” in the remainder of the pyranose ring might have reasonable validity, but, in many instances, the difference in reactivity of the p-nitrophenyl thioglycoside versus the p acetamidophenyl thioglycoside is not enough to make this work (Scheme 1 An alternative could be steric activation-deactivation at the anomeric centers of the donor and acceptor. An example using this concept is shown in Scheme 12. In the electronic activation-deactivation concept, deactivated p-nitrophenyl thioglycosides can, after functioning as glycosyl acceptors, be transformed into
THIOGLYCOSIDES AS GLYCOSYL DONORS
E
EnO* En0
OBn
OPent +A&
IDCP
AcO
OAc
OPent
n
"'
CH2CI2
0
191
6
OEnAc;%AcO
a:p = 1: 1, 62%
OPent OAc
Mootoo, Konradsson. Udodong, Fraser-Reid, 1988
En0
IDCP Eno*SEt En0 OEn
OEn
(CICHp)p-E1,0
Ezo*SEt EzO
OEz
OEz
Veenernan, van Boom 1990
a : p = 7 : 1, 84%
En0 deactivated Garegg, Hlllgren 1992
SCHEME 9.-"Armed"-"disarmed'
+ 18%
p-(1-3)
concept
activated p-acetamidophenyl thioglycosides and thus be carried on into further glycosylation reactions with a p-nitrophenyl thioglycosyl acceptor. This whole sequence can, in principle, be repeated several times over. Because this is not possible in the foregoing steric activation-deactivation concept, the latter is restricted to two glycosylations in sequence. Using steric anomeric deactivation, it is, however, possible to proceed with an oligosaccharide synthesis with a thioglycoside acceptor that is deactivated in the pyranose ring, as ~ h o w n ~ in ~.'~ Scheme 12.
VI. THIOGLYCOSIDES IN BLOCK SYNTHESIS OF OLIGOSACCHARIDES Thioglycosides have been used in a large number of oligosaccharide syntheses. A selection of reports in which thioglycoside glycosylation donors have played a pivotal role is shown in the reference l i ~ t . ' ~ - Three ~ * ~ of these are outlined as follows. The first two of these are typical of Hasegawa and co-workers' long series of papers detailing the synthesis of oligosaccharides terminated at the nonreducing end with sialic acid. In a
PER J. GAREGG
192
"'a 0 AcO
SX
OAc
+
-
H o ~ S - - OBn BnO Q " 2
&
S
~OAc
OBn o
~
~
B5%
Fugsdi. Garegg, Oscarson,RorBn, Silwanis 1990
50% Garegg. Silwanis Unpublishsd
-OGA
OCiiHz9
\ /
AcHN
NO?
H
O
~
C
AcO
NO REACTION
SCHEME
10. -Anomeric
-OcA
,
~
H
,
,
\ /
AcHN
70%GLYCOSIDE, u
I,
NHAc
1 I
activation/deactivation
synthesis9' of ganglioside GM,, the lactoside 1 (Scheme 13) carrying the versatile anomeric protecting (trimethylsily1)ethyl group at C- 1 was converted into the diol 2 by isopropylidenation at the 3',4'-positions, followed by benzylation of the remaining HO groups and subsequent hydrolytic removal of the isopropylidene group. The diol 2 was then glycosylated with the sialic acid glycosyl
'''
S
~
THIOGLYCOSIDES AS GLYCOSYL DONORS
B n O BnO
S
s
E
t
+
BZsZQNoz IDCP
' S BnO
S
BBzO z o
s
55% disacch. Slow reaction. a:p 4 1
OBz
OBn
"
193
E t OBn
s E OBZ
+
B & a-!!% ~a~~z 36% disacch. a:p 4 I
OBn
t
+
B
&
S
S a OBz
N
O
z
NIS 88% .H disacch. p only
Sliedregt. Zegelaajaarsveld, van der Marel, van Boom, 1993
SCHEME 11
donor 3 in the presence of NIS-TfOH in acetonitrile, which, through solvent participation at the anomeric center,89gave the trisaccharide 4 with the a-glycosidic bond and also regioselectively a (1-3) linked sialic acid residue in preference to the corresponding (1+=4)-linkedone. The 4'-OH group of 4 was then glycosylated with the thioglycosyl glucosamine donor 5 to produce the tetrasaccharide 6 with the required p-(1+4') linkage through participation at the glycosyl cationic intermediate by the phthaloyl group. The tetrasaccharide 6 was subsequently taken through a series of steps, including release of the silyl group, to produce a I-OH precursor, which was converted into its trichloroacetamido (7), used in the synthesis of the final ganglioside GM, (8). In the second example, the synthesis of an I-active ganglioside analogue9*is covered. The sialyl I antigen is shown in Scheme 14.
NISfTfOH (cat)
SEt
OBz SEt
OBz
Boons 8 el 1995
SCHEME 12
NIS-TfOH
3
C02Me
OAcoAc
OCH2CH2SiMe3
AcNH
5
59%
AcNH
A
OAcoAc C
AcNH AcO .- -
O C02Me Q
--
~
J
~
~
~
,
0 BnO OAc
N
I
OBZ
SCHEME 13
aNeuSAc(2+3)poGalp(
I-4)poClcpNAc(l-6)
\
p ~ G n l p1-4)poGlcpNAc( ( aNeuSAc(Z+3)p~Galp( I 4 ) p o C l c p N A c ( 1+3)
/
SCHEME 14
I+3)poGalp( 1+4)pDGlcp( 1+1 ICeramide
THIOGLYCOSIDES AS GLYCOSYL DONORS
195
In the analogue, the p-~-GlcpNAc-(1+3)-p-~-Galp-( 1+4)-p-D-Glcp trisaccharide moiety was replaced by a P-D-Glcp residue. The monomethoxybenzyl lactoside 9 (Scheme 1 3 , obtained by dibutyltin-mediated monoalkylation of 2-trimethylsilylethyl p-lactoside was converted into the 2,2',3,6-tetrabenzyl4',6'-O-benzylidene derivative, which was then deprotected at 0-3' by oxidation with 2,3-dichloro-5,6-dicyanobenzoquinoneto form 10. Sodium cyanoborohydride-hydrogen chloride-rnediated ring opening of 11, followed by acetylation, produced the glycosyl donor 12, condensation of which with the acceptor 10 gave the trisaccharide 13, which, in turn, was debenzylidenated to give the 4',6'diol 14. Condensation of 11 with 14 gave preferential glycosylation at the primary OH group, producing the branched tetrasaccharide 15, from which the single acetyl group was then removed. Another partial glycosylation reaction, between the diol 16 and the thioglycoside disaccharide glycosyl donor 17, produced the key monohydroxy compound 18. In the crucial step of the synthesis (Scheme 16), the disaccharide glycosyl donor 17 was used once again, in condensation with the acceptor 19 having two free OH groups, to produce the octasaccharide 20. This product was then converted in 7 steps via the 1-trichloroacetamido compound, analogous to the synthesis described in Scheme 15, into the final compound 21. The synthesis is an excellent example of the use of thioglycosides as glycosyl donors in the block synthesis of complex oligosaccharides as well as the use of partial glycosylation of diols to achieve short paths to the target. The third example99 is the synthesis of a linear decasaccharide containing alternate p-(1-3) and p-( 1+4)-linked D-glucopyranosyl residues (Scheme 17). The corresponding decasaccharide, fully C-deuterated except for the central cellobiosyl residue, was required for NMR and conformational analysis studies. The synthesis of the unlabeled decasaccharide is covered here. Ethyl 2-0benzoyl-4,6-O-benzylidene-I-thio-~-~-glucopyranoside (22) was chloroacetylated and the thioglycoside product was converted into the glycosyl bromide 25. Benzoylation of 22, followed by regioselective reductive ring opening of the benzylidene group, gave the 4-OH compound 26. Silver triflate-promoted condensation of 25 with 26 gave the key disaccharide building block 27 in excellent yield. Part of 27 was converted into the corresponding methyl glycoside 28, and this product was then dechloroacetylated with aqueous pyridine to give the 3'OH compound 29. Next followed 4 cycles of DMTST-promoted condensation of 3'-, 3"', 3""', and 3"""'-OH compounds with the thioglycoside 27, and a dechloroacetylation step after each condensation. After deprotection by debenzoylation followed by catalytic hydrogenolysis, the decasaccharide 30 was obtained in 8% total yield from 27 and 29. The synthesis thus was based on the use of thioglycoside glycosyl donors and the chloroacetyl group being removable in the presence of benzoyl groups.
PER J. GAREGG
196
PhT*sMe BnO
I
I-
NIS l1- TfOH
15
4 16
61%
OACOA~
Ph
AcO
17 BzoDMTST
OBn
Ph
SCHEME 15
"NPhth
THIOGLYCOSIDES AS GLYCOSYL DONORS
I
197
OH
OAc OAc
A c AcNH AcO
O
C02Me
U
620
e
2
OBI
n
& NHAc o
OHe
0 S BnO
OBn OSE
20
28%
AcO"' AcNH
SCHEME 16
VII. THIOGLYCOSIDES AS GLYCOSYL ACCEPTORS IN OLIGOSACCHARIDE SYNTHESIS Thioglycosides containing free OH groups readily tolerate silver triflate-promoted glycosylations with glycosyl bromides and chlorides, and also tin(I1) chloride-silver perchlorate-activated glycosylation, and several examples have
PER J. GAREGG
198
T R = H
)*
2 3 Y =‘OBZ BZ
NaCNBH4-THF
qz$ .+ l CIAUJ
SEI
020
082
28
R = SEt C24, 25, R = Br
3. Repeat cycle -
4 times with
cycle Deprotect
I on
on
‘on
30
I ClAcO = CICH2C(0)0 I SCHEME 17
been referred to throughout this ~hapter.’~,~~*’’ -75.99 They can also be subjected to silver triflate-promoted reactions with 1-piperidinecarbodithioate glycosyl donorsX6Syntheses of Moraxella catarrhalis serotype A oligasaccharides depended heavily on the use of glycosyl bromides and thioglycoside acceptors, and the subsequent use of the latter for joining larger fragments.Is4 Thioglycosides can also be used as acceptors in glycosylation with trichloroacetimidates.IX The “armed- disarmed” concept is tranferrable to having thioglycosides both as donors and acceptor^^^.^* (Scheme 9). Anomeric activation can, in favorable instances, also be used for this purposey3(Scheme 10). VIII. GLYCOSYL SULFOXIDES, SULFONES, AND SELENOGLYCOSIDES AS GLYCOSYL DONORS Although the aim of this chapter is specifically to survey the use of thioglycosides in glycosylation reactions, the presentation is incomplete without some information concerning glycosyl sulfoxides and selenoglycosides in gl ycosylation
THIOGLYCOSIDES AS GLYCOSYL DONORS
I99
-78 “C
-70 “C
15%
25%
SCHEME18
reactions. Glycosyl sulfoxides can be activated by catalytic amounts of triflic acid in the presence of a glycosyl acceptor to produce a glycosidic bond. Sulfoxides, readily obtained by oxidation of the corresponding thioglycosides are activated by triflic anhydride in the presence of alcohols to produce glycosides. Moreover, in a synthesis of the ciclamycin trisaccharide, an advantage was that a glycosyl p-methoxyphenyl sulfoxide is more reactive than a glycosyl phenyl sulfoxide, which in turn is more reactive than a phenyl thioglycoside. This difference made possible the one-step synthesis of the trisaccharide shownlX6in Scheme 18. The sulfoxide glycosylation reaction was subsequently used in the synthesis of the calchiceamine oligosaccharide, containing an N - 0 glycosidic 1inl~age.l~’ Glycosyl sulfones, normally of low reactivity, have been reported as glycosyl donors, activated by magnesium bromide etherate.lxX Selenoglycosides have also emerged as valuable intermediates in oligosaccharide synthesis. Thus, the following has been described for phenyl selenoglycosidesIx9: 1. “Disarmed” as well as “armed” (see Section V and Scheme 9) phenyl selenoglycosides are reported to be activated by silver triflate in the presence of potassium or silver carbonate in the presence of “armed” ethyl thioglycoside acceptors, to produce ethyl thiodisaccharides in excellent yields. 2. Glycosyl bromides can be used as donors in the presence of phenyl selenoglycoside acceptors, using silver triflate as a promoter in the presence of collidine.
200
PER J. GAREGG
3. Glycosyl trichloroacetimidate donors in the presence of selenoglycoside acceptors can be used with triethylsilyl triflate as promoter. This extension considerably enhances flexibility in choosing strategies for oligosaccharide synthesis (compare Scheme 2).
IX. CONCLUSIONS The use of thioglycosides in block synthesis of oligosaccharides is now well established. Together with the other glycosylation methods listed in Scheme 1 and newly emerging methods based on glycal ~hemistry?~ methodology that allows chemists to tackle the synthesis of large, complex oligosaccharides is now available. This is particularly significant for the further development of glycobiology. The flexibility of glycosylation strategies emanating from thioglycosides, as shown in Scheme 2, makes them particularly attractive for oligosaccharide synthesis. Further flexibility and possibilities arise from the use of glycosyl sulfoxides and selenoglycosides, as briefly covered in this chapter. There is yet no single, coherent strategy for oligosaccharide synthesis. Each particular problem must be analyzed as a separate event. Because many glycosylation reactions (particularly of 1,2-cis glycosides) are not stereospecific, carbohydrate chemists are still some distance from reliable solid-phase synthesis, such as those enjoyed by oligonucleotide and oligopeptide chemists.
ACKNOWLEDGMENTS I am deeply indebted to all of my present and past co-workers who have participated in the unfolding development and use of thioglycosidesin glycosylation reactions.
REFERENCES 1. 2. 3. 4. 5.
6. 7. 8. 9. 10. 11. 12. 13.
K. Matsuzaki,Y.Ito, Y.Nakahara, and T. Ogawa, Tetrahedron Left., 34 (1993) 1061- 1064. W. L. Evans, D. D. Reynolds, and E. A. Talky, Adv. Carbohydr. Chem., 6 (195 1) 27-81. G. Wulff and G. Rohle, Aizgew. Chem., 86 (1974) 173-208. R. U. Lemieux, Chem. Soc. Rev., 7 (1978) 423-452. P. Sinay, Pure Appl. Chem., 50 (1978) 1437-1452. A. F. Bochkov and G. E. Zaikov, Chemistry of the 0-Glycosidic Bond; Formation and Cleavage, Pergamon Press. Oxford, 1979. H. Paulsen,Angew. Chem., Int. Ed. Eng/., 21 (1982) 155-173. H. Paulsen, Chem. Soc. Rev.. 13 (1984) 15-45. R. R. Schmidt,Angew. Chem.. Int. Ed. Engl., 25 (1986) 212-235. H. Kunz, Angew. Chem., Int. Ed. Engl., 26 (1987) 294-308. P. J. Garegg and A. A. Lindberg, in J. F. Kennedy (Ed.), Carbohydrate Chemistry, pp. 500-559, Clarendon Press, Oxford, 1988. R. R. Schmidt, Pure Appl. Chem., 61 (1989) 1257-1271. H. Paulsen, Angew. Chem., Int. Ed. Engl., 29 (1990) 823-839.
THIOGLYCOSIDES AS GLYCOSYL DONORS
20 1
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ADVANCES IN CARBOHYDRATE CHEMISTRY AND
BIOCHEMISTRY. VOL.
52
DIHEXULOSE DIANHYDRIDES
BY MERILYNMANLEY-HARRIS Chemistry Department. University of Wuikato,Private Bag 3105, Hamilton, New Zealand AND
GEOFFREY N. RICHARDS The Shujizadeh Center for Wood und Carbohydrate Chemistry. University of Montana, Missoula, Montana 59812 USA 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . .................................... 11. Nomenclature
... ... ............ . ........... . . . . . . . . . . . . . . . . . . ............. . . . IV. Di-o-fructose Dianhydrides from Natural Sources ........... 1. Isolation of Di-o-fructose Dianhydrides from Hig s ....................... V.
VI.
207 208 210 213 213 2. Di-D-fructose Dianhydrides and Microorganisms . . . . 213 Dihexulose Dianhydrides by Protonic and Therma 216 I . Protonic Activation Using Anhydrous Hydrogen Fluoride . . . . . . . . . . . . . . . . . . . . . . . . . 216 2. Spirodioxanyl Pseudo-oligosaccharides . . . . . . . . . . . . . . . . . . . . . . ............. 220 3. Protonic Activation with Acids Other than HF . . . . . . 22 1 4. Thermal Activation in the Presence of Acids . . . . . . . 222 5. Thermal Activation without Acids . . . . . . . . . . , . . . . . . . . . . . . . . , . . . . . . . . . . . . . . , . . . . . 222 6. The Chemical Nature of Caramels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 Conformational Energies in Dihexulose Dianhydrides and the Control of Product Distributions . . . . . . . , . . . . . . . . . . . . . . , , . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . 224 1. Electronic Control of Conformation . . ... , . 224 2. Energetic Outcomes of Conformational Rigidity . . . . . . , . . . . . . . . . . . . . . . , . . . . . . . . . . 228 3. Thermodynamic Versus Kinetic Control of Product Distributions . . . . . . . . . . . . . , . . . . . 228 4. Acid Hydrolysis of Di-o-fructose Dianhydrides and Their Per-0-methyl Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . , . . . . . . . . . . . . . . . . . . . 232 Di-o-fructose Dianhydrides and Industry . . . . . . , . . . . . 232 . .. . .. . . Uses of Di-o-fructose Dianhydrides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 1. Di-D-fructose Dianhydrides and Nutrition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 2. Di-D-fructose Dianhydrides in Chemical Synthesis . . 234 References . , . . . . . . . . . . . . , . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . , . . . . 235 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 .
VII. VIII.
.
I
I. INTRODUCTION Di-D-fructose dianhydrides were first reviewed in 1946 as part of a chapter’ in this Series. That work described the outcome of a burst of activity in this field, 0096-5332/Y7 $25.00
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Copyright 0 1997 by Academic Press. All rights of reproduction in any form reserved.
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which occurred in the 1920s and 1930s. At that time, four di-D-fructose dianhydrides were known and the structure of three of these had been elucidated, although their anomeric configurations were not known. From that time until the early 1970s, activity in this area was sporadic, motivated by the interest of NMR spectroscopists and by the nuisance value of di-D-fructose dianhydrides in the sugar industry. The topic was reviewed again2 in 1963 and mentioned briefly3 in this Series in 1967. In 1972, the discovery of the formation of di-D-fructofuranose 1,2’ :2,3’-dianhydride by an extracellular inulase of Arthrobacter ureafaciens stimulated activity in Japan. This work has been directed mainly toward the production and metabolism of this class of compounds by microorganisms. During the past two decades, world-wide interest in these compounds has undergone a renaissance as part of an overall increase of interest in fructose and its polymers. The potential use of these compounds as sweeteners and as bifidogenic factors has also acted as a stimulus. This chapter describes 27 dihexulose dianhydrides and, by a liberal interpretation of the title, a further 6 mixed dianhydrides of glucose and fructose. The majority of these compounds have been characterized, although with varying degrees of rigor. Also mentioned are the socalled spirodioxanyl pseudo-oligosaccharides, which are composed of chains of glycose residues attached to di-D-fructose dianhydride moieties. These have been prepared synthetically, but also appear to be formed in almost infinite variety during thermal and protonic activation of fructose-containing saccharides. The literature in this field is confusing because of a somewhat haphazard method of nomenclature that has arisen historically. This is compounded by some mistakes in structure determination, reported in early papers, and which are occasionally quoted. The first part of this chapter deals with nomenclature and with a brief overview of early work. Subsequent sections deal with the formation and metabolism of di-D-fructose dianhydrides by micro-organisms, and the formation of dihexulose dianhydrides by protonic and thermal activation. In relation to the latter topic, recent conclusions regarding the nature of sucrose caramels are covered. Other sections deal with the effects of di-D-fructose dianhydrides upon the industrial production of sucrose and fructose, and the possible ways in which these compounds might be exploited. An overview of the topic of conformational energies and implications for product distributions is also presented. 11. NOMENCLATURE Dihexulose dianhydrides are intermolecular cyclic acetals formed by the condensation of two hexulose molecules with the elimination of two water molecules, and the formation of two linkages involving the 2- and one other position of each component. They are named4 by placing the word dianhydride after the names of the two parent monosaccharides. The order of precedence for these
DIHEXULOSE DIANHYDRIDES
209
two names is decided alphabetically; thus, fructose precedes sorbose, furanose precedes pyranose, the configurational prefix D precedes L, and the anomeric prefix a-precedes p-. The position of each anhydride linkage is given by a pair of locants, with the unprimed locant written first in each pair, indicating the positions of the two hydroxyl groups involved. The locants relating to the second monosaccharide named are primed. Both pairs of locants precede the word dianhydride. Thus, compound 1 is named as (Y-D-frUCtOfUTanOSeP-D-fructopyranose I ,2’ :2,1 ’-dianhydride,2 is called di-p-D-fructofuranose 1,2’ :2,3‘-dianhydride, and 3 is known as p-D-fructopyranose a-L-sorhopyranose 1,2’ :2,1‘-dianhydride. The formula illustrations here generally adopt the Haworth convention, with the first-mentioned monosaccharide depicted on the left in the “normal” orientation. Table I* contains a list of the dihexulose dianhydrides currently in the literature, together with some mixed fructose-glucose dianhydrides. Trivial and IUPAC names are included. Each entry has a proposed abbreviation. Because of the great similarity of structure between all the compounds in Table I, these abbreviations are used, rather than numbers, in the context of this chapter. Thus, 1 is named as a-D-Fruf- 1,2‘ :2,l’-p-~-Frup,2 as P-D-Fruf- 1,2’ :2,3’-p-~-Fruf, and 3 as P-D-Frup- 1,2’ : 2,l I-a-L-Sorp.
1
The practice of including the conformation after the name of the parent monosaccharide should be used only with caution because not all conformations are known with certainty. In the case of furanose rings especially, conformations might differ between the crystalline and solution states. *All tables are grouped at the end of this chapter.
210
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
Historically, the trivial names diheterolevuloson I , 11, 111, and IV have been used to describe the di-D-fructose dianhydrides, which contain one or two pyranose rings. Similarly, the names di-D-fructose dianhydride (or difructose anhydride) I , II,11I, I K and V have been used to describe those compounds in which two furanose rings occur. The names diheterosorbosan I and I1 have also been coined. Trivial names should not be used in other than a secondary manner; for example, they may be listed in parentheses after the IUPAC name. 111. HISTORICAL OVERVIEW
In 1926, Pictet and Chavad isolated a compound [a-~-Frup-l,2':2, 1'-p- ~ Frup (4)] from the mixture of products of the low-temperature treatment of fructose with concentrated hydrochloric acid. They called this compound di-he'te'role'vulosane (diheterolevulosan) and deduced that it was a dimeric dianhydride. The remainder of the product, which they termed he'te'ro-le'vulosane(heterolevulosan), was ascribed to a monomeric fructose anhydride.
bH
4
Schlubach and Behre6 hydrolyzed the per-0-methyl derivative of the same diheterolevulosan and showed that the only product was 3,4,5-tri-O-methylfructose. Subsequent studies718confirmed the structure of diheterolevulosan as a diD-fructopyranose 1,2' : 2,l '-dianhydride. Wolfrom and Blair8 also showed that the major constituent of he'te'ro-le'vulosanewas another dimeric dianhydride [aD-Fruf-1,2' :2,l '-p-~-Frup (l)],which they called diheterolevulosan 11 and which was subsequently shown9 to be a o-fructofuranose D-fructopyranose 1,2' :2,l '-dianhydride. These two diheterolevulosans were also obtained by heating concentrated aqueous solutions of fructose.' A third compound (p-D-Fruf-
DIHEXULOSE DIANHYDRIDES
21 1
I ,2' :2,l '-p-~-Frup),termed'' diheterolevulosan 111, was isolated from the product of treatment of fructose with cold, concentrated hydrochloric acid. This was tentatively assigned either as di-D-fructopyranose 1,2' :2,3'-dianhydride or as an anomer of diheterolevulosan 11, the latter structure being the more favored. Wickberg" subsequently obtained a fourth compound (P-D-Frup-I ,2' :2,l '-P-DFrup), which he termed diheterolevuiosan ZV and assigned the correct structure and the correct anomeric configurations, using Hudson's rules of isorotation.
The first di-D-fructofuranose dianhydride was isolated from hydrolyzed inulin by Jackson and GoergenI2 in 1929 and designated difructose anhydride I [a-oFruf-1,2' :2,1'-P-D-Fruf (S)]. The same compound was isolated by Irvine and StevensonI3 in the same year, by treating tri-0-acetylinulin with fuming nitric acid, but it was incorrectly assigned as a monomeric fructose anhydride. Haworth and c o - w o r k e r ~ ' subsequently ~~'~ showed that the structure of difructose anhydride I was a di-D-fructofuranose 1,2' :2,l '-dianhydride and that k i n e and Stevenson's product was identical with that of Jackson and Goergen. A further two difructose anhydrides I1 and I11 [respectively, P-D-Fruf-l,2' :2,3'-P-~-Fruf (2) and a-D-Fruf-l,2' :2,3'-p-D-Fruf (6)] were isolated from hydrolyzed inulin by Jackson and McDonald.I6 Some careful work elucidated the structure of difructose anhydride I11 as di-D-fructofuranose 1,2' :2,3'-dianhydride,17 but the idea that difructose anhydride I1 might be an anomer of difructose anhydride 111 was dismissed and difructose anhydride I1 was incorrectly assigned as di-ofructofuranose 2,l' :4,2'-dianhydride.'~'~
212
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
The correct structure of this compound, which was predicted by Wolfrom et a/.," was subsequently confirmed by X-ray cry~tallography.'~ Nevertheless, this
mistaken identification has been quoted in the literature as late2' as 1990. A crys:2,3'-P-~-Fruf(6) has also been published." tal structure of a-~-Fruf-1,2' In 1952, Wolfrom and Hilton demonstrated that L-sorbose was also capable of forming dimeric dianhydrides?' and they postulated sorbofuranosyl and pyranosy1 cationic intermediates. In 1955, Boggs and Smith23postulated a fructofuranosyl cationic intermediate in the formation of per-0-acetyl 01-~-Fmf1,2' :2,l '-P-D-Fruf [di-D-fructose anhydride I ( 5 ) ] from inulin triacetate. They indicated that three adjacent P-2,l '-linked fructofuranosyl units would be required for formation of the dianhydride. The advent of NMR spectroscopy permitted the assignment of anomeric configurations and conformations of the di-D-fructose dianhydrides. In 1963, Lemieux and NagarajanZ4assigned the configurations of di-D-fructose anhydride I [01-~-Fruf-1,2':2,l '-p-~-Fruf( 5 ) ] by 'H NMR spectroscopy of the peracetate. Using the Karplus relationshipz5together with evidence from periodate oxidation, they deduced conformational assignments of ' E and E, for the a and p rings, respectively. A subsequent26 crystal structure of the 3,4,3',4'-tetra-0acetyl-6,6'-di(O-triphenylmethyl)derivative of 5 confirmed the anomeric configurations, but found E, and 'T3 conformations, respectively, for the 01 and P rings. The conformations of CX-D-FIU~1,2' :2, I '-6-D-Frup (4,01-~-Fmf1,2' :2,1'-(3-~Frup (I), P-~-Fruf-1,2':2,1'-P-~Frup, and P-D-Frup-1,2' :2,1'-P-D-Frup (diheterolevulosans I-IV) have also been assigned2' using 'H NMR. The conformation of the di-P-D-fructopyranose dianhydride (diheterolevulosan IV) agrees with the crystal structure." The conformation assigned to the pyranose ring of 01-o-Fr~f-I ,2' :2,l '-p-~-Frup(diheterolevulosan 11) agrees with the crystal struct ~ r e ?but ~ the furanose ring was assigned the 3E conformation, as compared with the OE conformation observed in the crystal. "C NMR spectroscopy has been used to assign the configurations of the same four c~mpounds.~" The configuration of the di-P-D-fructopyranose dianhydride (diheterolevulosan IV) was correctly assigned, as confirmed by X-ray crystallography.2xP-~-Frufl,2' :2,l '-p~-Frup(diheterolevulosan 111) had been identified" as being one of two possible structures, as already indicated. However, the assumption was made in Refs. 27 and 30 that it was an anomer of 01-~-Fruf1,2':2,1'-P-~-Frup (l),and the P,p configuration was assigned. Defaye et al.3' concurred with this assumption and this is the structure used in the tables published at the end of this chapter. The fu1,2':2,1 '-P-~-Frup[diheterolevulosan 11, ranose and pyranose rings of OL-D-FIU~ (l)]were originally assigned the configurations j3 and a,respectively, in Ref. 30, but this assignment was reversed in Ref. 31 and was subsequently confirmed by the crystal structure.29 a-~-Frup-l ,2' :2,l' -P-~-Frup[diheterolevulosan 1, (4)] was initially assigned the a,aconfiguration in Ref. 30. Although reservations were expressed because
DIHEXULOSE DIANHYDRIDES
213
two anomeric signals were observed in the NMR spectrum, these were dismissed on the basis that the two fructose rings had previously been shown to have different conformation^.^' However, examination of models of di-a-D-fructopyranose 1,2‘ :2, I ‘-dianhydride indicate that, to conform with the anomeric and exo-anomeric effects, both pyranose rings must have the same ’C, conformation, that the central ring would be a boat, and that the molecule would have C, symmetry. Thus, only six signals should have been observed in the I3C NMR spectrum if the molecule had been the a,a anomer. In fact, in a later study, an Xray analysis cited in Ref. 31, but for which the details do not appear to be available, indicated the a,P configuration, which is in accord with the NMR data.
Iv. DI-D-FRUCTOSE DIANHYDRIDES FROM NATURAL SOURCES 1. Isolation of Di-D-fructose Dianhydrides from Higher Plants In 1933, Schlubach and Knoop3’ isolated a di-D-fructose dianhydride from Jerusalem artichoke and tentatively identified it as difructose anhydride I [a-DFruf- 1,2’ :2,1 ’-P-~-Fruf( 5 ) ] . Alliuminoside (?-D-fructofuranose-?-D-fructofuranose 2,6’ :6,2’-dianhydnde) was isolated from tubers of Allium sewertzowi by S t r e p k ~ vin~ 1958. ~ U ~ h i y a m ahas ~ ~demonstrated the enzymic formation of aD-Fruf-1,2’ :2,3’-P-~-Fruf[dh-fructose anhydride I11 (6)] from inulin by a homogenate of the roots of Lycoris radium Herbert.
2. Di-D-fructose Dianhydrides and Microorganisms The biosynthesis and degradation of fructans by microbial organisms has been reviewed in detail recently.” Additionally, a review of the production of di-Dfructose dianhydrides from inulin and levan by enzymes has been published in Japanese.’6 This account is therefore limited to a general overview. In 1972, Tanaka er uI.~’isolated an extracellular inulase from Arthrohacter ureufuciens, a soil bacterium, which degraded inulin to a-~-Fruf-l,2’ :2 , 3 ’ - p - ~ Fruf [di-D-fructose anhydride I11 (6)] and some residual oligosaccharides. This enzyme was an inulin D-fructotransferase [inulin D-fructosyl- 1,2-P-~-fructofuranosyltransferase (EC2.4.1.93)] and its mode of action differed from that of the common inulases. The enzyme was purified3*and its action against oligofructans and bacterial levans was studied.39 It was found to attack (2+l)-P-linked fructan molecules from the non-reducing fructose end and to require at least two adjacent (2-+1)-P-fructofuranosyl linkages; (2-+6)-P-fructans were not attacked. A further, intracellular enzyme of A . ureufuciens hydrolyzes a - ~ - F r ~ f,2‘ - l :2,3 ’-PD - F ~ (u6~) reversibly to inulobiose and thence to f r u ~ t o s e ~ *This - ~ ’ two-stage hydrolysis requires cleavage, first of the (2+3)-linkage, reversibly by an a-fructofuranosidase, then of the (2+1 )-linkage by a P-fructofuranosidase. The two
214
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
activities show markedly different sensitivities to heat4”;hence, it can be associated with more than one enzyme. Inulin fructotransferases have also been isolated42,43 from Arthrobacter gfobiformis Cl l-1, Arthrobacter ilicis OKU17B$4 and from Enterobacter sp. S45.45v46A strain, H65-7, of Arthrobacter of unknown species has been r e p ~ r t e d ~to ’.~ exhibit ~ a remarkably high level of inulin fructotransferase activity that is stimulated by the addition of yeast or, to a lesser extent, meat extracts to the culture medium. The precise stimulatory factor is unknown. A process for the manufacture of CL-D-FIU~1,2’ :2,3’-P-D-Fruf (6)using inulin fructotransferase from Pseudomonas fluorescens MZ No. 949 has been A procedure exists for the detection of inulin fructotransferase in described!’ crude preparations by activity ~taining.~’ N a k a ~ a m a ” -has ~ ~ studied induction and activity of inulin fructotransferase in Arthrobacter ureafaciens. C L - D - F 1,2‘ ~ ~ F:2,3‘-p-~-Fruf (6)induced the production of extracellular and cell-bound inulin fructotransferase during the transitional phase between lag and exponential growth phases. Because A. ureafaciens possesses an enzyme capable of hydrolyzing a-~-Fruf-1,2’ :2,3’-p-~-Fruf (6), the precise nature of the inducing agent is not known. A study of the effect of various substances upon the formation and activity of inulin fructotransferase indicated that the inducing agent played a part in the de n o w synthesis of the enzyme.51.52,53 An extracellular enzyme [levan fructotransferase, (EC 2.4.1. lo)] that carries out an intramolecular transfructosylation upon levan to produce p-~-Fruf 2,6’ :6,2’-P-~-Fruf[difructose anhydride IV (7)]has been identified in A . ureafa~iens.~~.~’
OH
I
-OH
DIHEXULOSE DIANHYDRIDES
215
This enzyme has been purified56and has been shown to exhibit three types of activity.57In addition to the aforementioned intramolecular transfructosylation, the enzyme is capable of catalyzing intermolecular fructosyl and levanbiosyl transfers to a levanbiosyl acceptor,57 and a reaction mechanism and active-site structure have been de~cribed.~' The enzyme is active against levans of both bacterial and plant although the latter are degraded to a greater extent. One or two P-(2+6)-linked fructosyl residues are thought to remain at branch points,"' and a trisaccharide, 1-O-P-D-fructofuranosyl-P-D-fructofuranose p-Dfructofuranose 2,6' :6,2'-dianhydride was claimed to be formed62by intramolecular transfructosylation activity upon a branch point. Levan fructotransferase activity is exhibited by Pseudomonas juorescens and processes for the manufacture of P-~-Fruf-2,6':6,2'-p-~-Fruf (7), using two different strains of this bacterium, have been described.'"@ An extracellular inulin fructotransferase that results in the formation of OI-DFruf- 1,2' :2,l ' - p - ~ - F r ~[difructose f anhydride I (5)] has been purified from Arthrobacter globiformis S 14-3,65,66from Arthrobacter sp. MCI-2493'? and from Streptomyces sp. MCI-2524.6x An enzyme that brings about the formation of a-D-Fruf- 1,2' :2,l '-p-~-Fruf(5) has been isolated from the fungus Aspergillus fumigatus F r e s e n i ~ s . ' ~This , ~ ~ enzyme catalyzes the reversible formation of a-D-Fruf- 1,2' :2,1 '-p-D-Fruf (5) from inulobiose." The equilibrium composition favors the cyclization to the extent of 85%, as compared with 15% of the hydrolysis p r ~ d u c t .The ~ ' authors speculated that this enzyme might constitute a regulatory step in the metabolism of inulin; a similar role for the analogous enzyme active against O I - D - 1,2' F ~ :~2,3'-p-~-Fruf ~ (6) was suggested.?' O I - D - F1,2' ~ ~:2,6'-P-~-Fruf ~ (8) has been isolated from the culture media of Aspergillus fumigatus Fresenius grown upon inu1i1-1.~'
Although it was demonstrated that this was not an artifact, the enzyme responsible for its formation has not yet been isolated. It is obvious that there remain unanswered a number of interesting questions relating to the role of the di-D-fructose dianhydrides in Nature. First, it is not
216
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
obvious whether the di-D-fructose dianhydrides isolated from plants in Refs. 32 and 33 are of plant or microbial origin. In Ref. 34, the root homogenate was sterilized before use to inactivate contaminating microorganisms. Thus, this is the only authenticated report of this type of activity in higher plants. To understand the significance of this activity, it will be necessary to extend our knowledge of its occurrence. Fructans, in general, have limited occurrence in higher plants, and their presence is often associated with the ability to withstand exposure to low temperature^.^^ The location of di-D-fructose dianhydride-related activity within an individual plant, temporal and geographical influences, and the occurrence of activity in different genera and/or species require further study. Little information is available on the specific control of fructan metabolism in higher plants73 or in microorgani~ms.~~ If a regulatory role is envisaged for the di-D-fructose dianhydride enzymes, as has been suggested for microorganism^,^' then more detailed studies are required.
V. DIHEXULOSE DIANHYDRIDES BY PROTONIC AND THERMAL ACTIVATION OF SACCHARIDES For the purposes of this chapter, an arbitrary distinction is made between protonic and thermal activation, wherein protonic activation is caused by the action of acid at room temperature or lower, and thermal activation refers to the use of elevated temperatures with or without the addition of acid. In fact, in both cases, the initial steps in the postulated mechanisms are protonation of the C-2 oxygen atom followed by elimination of the aglycone to yield a ketohexofuranosyl or pyranosyl cation, which is the reactive intermediate; in certain circumstances, this might be in equilibrium with the derived glycosyl fluoride.
1. Protonic Activation Using Anhydrous Hydrogen Fluoride Hydrogen fluoride (HF) is a strongly protonating, highly polar solvent that is liquid from -83.4" to 19.5"C. The high dielectric constant, low viscosity, and long liquid temperature range make liquid HF an excellent solvent for a wide range of compounds, including carbohydrates, amino acids, and proteins. Molecules susceptible to the elimination of water (such as cellulose) frequently dissolve without d e h y d r a t i ~ n The . ~ ~ ability of HF to cleave the glycosidic bond in carbohydrates means that it can be used for structure determination. The latter subject has been reviewed in this series.75A review of reactions brought about by HF in carbohydrates at the anomeric and non-anomeric positions, including glycoside formation, has also a~peared.'~ The use of HF is attended by certain practical difficulties. For this reason, HF is often used in the form of a less-volatile complex with an N-donor base. The
DIHEXULOSE DIANHYDRIDES
217
combination of anhydrous HF with a proton acceptor was first used by Hirschmann et al.77to increase the effective concentration of fluoride ions in a reaction mixture. Pyridinium poly(hydrogen fluoride) (30% pyridine-70% hydrogen f l ~ o r i d e )is~ ~ often . ~ ~used as a general-purpose fluorinating agent. This solvent/reagent has a small amount of free HF in equilibrium with the poly(hydrogen fluoride). This reagent is capable of acting as a protonating agent and is a powerful fluoride donor. Thus, cyclopropane is opened to yield 1-fluoropropane without any rearrangement of the cation.” treated D-fructose and inulin with anhydrous HF and obtained Defaye et high yields of a mixture of di-D-fructose dianhydrides. The products included aD-Frup-1,2’:2,1’-P-~-Fmp (4), a-D-F’ruf-1,2’ :2,1’-p-~-FrUp (I), p-~-Fruf1,2’ :2,l ’-P-~-Frup,P-D-Frup-1,2‘:2,l ’-P-~-Frup(diheterolevulosans I-IV), a~-Fmf-1,2‘:2,1’-P-~-Fruf[difructose anhydride I (S)], and a hitherto unknown isomer: P-~-Fruf-2,1’:3,2’-P-~-Frup(9). The structure of the latter was deduced by examining the ‘H NMR spectrum of the peracetate.
HO
&H
&H
9 The ratio of the different isomeric products was found to vary with time, temperature, and initial concentration. This suggested that some kind of equilibration was occurring between isomers. 13C NMR spectroscopy of a reaction mixture showed, upon cooling, the reversible formation of a pair of signals in the anomeric region. These signals were ascribed to the anomeric carbon atoms of fructofuranosyl fluorides (lo), which were presumed to be in equilibrium with the reactive fructofuranosyl cation, 11.
218
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
A mechanism was proposed3’ for the formation of di-D-fructose dianhydrides from inulin and fructose. It was suggested that CY-D-FI-LI~ 1,2’ :2,l ’-p-~-Fruf [difructose anhydride I (5)] formed first and then isomerized via ionic intermediates to produce the remaining products. Important support for the concept of the reversibility of the isomerization was the observation that a-~-Frup-l ,2‘ :2,1’+~-Frup(4) and P-D-FI-UP1,2’ :2,l ’-P-D-FIu~produced, upon treatment with HF, the same product mixture as did D-fructose. The figures cited for the proportions of the different isomers in product mixtures in Ref. 31 and in Refs. 80 and 82 covered later, are of considerable value in qualitative terms, but they are, of course, not of high accuracy. They were obtained by integration of the 13CNMR spectrum in the anomeric region3’or in the secondary carbon region.’” Although the isomers have similarities of structure and size, they are likely to have very different conformations, resulting in different through-space interactions. Furthermore, I3C NMR integration is notoriously unreliable, and there is no indication in these reports that such precautions as inverse gated decoupling and long relaxation delays were used. The authors provide alternative figures for some isomers in Refs. 31 and 80, which were obtained by GLC of the per-0methylated product mixture. In many cases, these are in agreement with the NMR data, but, in some instances, there are significant differences. The authors considered8’ that this difference is more reasonably attributed to reaction occurring during the isolation of the products from the HF solution. Treatment of L-sorbose with anhydrous HF8” gave rise to an analogous mixture of products: a-~-Sorp-1,2’:2,1’-P-~-Sorp(12), P-~-Sorf-1,2’:2,1’-a-~-Sorp (13), a-~-Sorf1,2’:2,1’-a-~-Sorp, a-~-Sorp-1,2’:2,1 ’-a-L-Sorp, a-~-Sorf2,l’ : 3,2’-a-~-Sorp,and a-~-Sorf-1,2’:2,1‘-P-~-Sorf (14). Only two of these compounds, a-~-Sorp-1,2’:2,l ‘-p-L-Sorp (12) and P-~-Sorf-l,2’:2,1’-a-~-Sorp (13) had been identified previously.22
txi
12
13
DIHEXULOSE DIANHYDRIDES
219
The new compounds were assigned structures by examination of their I3C NMR spectra and of the ‘H NMR spectra of the peracetates. A similar mechanism to that previously postulated for fructose and i n ~ l i n , ~ and ’ involving a sorbofuranosyl fluoride was suggested for the formation of these isomers. In both Refs. 3 1 and 80, formation of the 2,3-linkage was associated with more-rigorous conditions.
bH
14
Treatment of inulin triacetate with fuming nitric acid results in the formation only of a-D-Fruf- 1,2’ :2,l ’-p-~-Fruf[difructose anhydride I (5)]’3,23 because the 0-acetyl substituent at C-3 blocks formation of the 2,3-linkage. When inulin triacetate was treated with anhydrous HEx2 a-~-Fruf 1,2’ :2,l ‘-P-D-Fruf (5) was formed, together with an isomer, which was revealed by its NMR spectrum, either as the &,a-or the p,p- anomer. The latter configuration was assigned on the basis of energetic considerations. This assignment has subsequently been reversed,x3(see section v-6 later). The 13C NMR spectrum of the crude productmixture displayed the signals for the anomeric carbon atoms of a number of glycosy1 fluorides. Different times and positions of cleavage of the inulin chain would result in a number of different fructofuranosyl fluorides. The use of di-0isopropylidene blocking groups on L-sorbose” resulted, upon treatment with anhydrous HF, in the formation of the novel compound a-~-Sorf-2,1’:3,2’-ol-~Sorf (15), the structure of which was assigned by examination of the ‘H NMR spectrum of the peracetate. The assignment of configurations in this way involves the assumption that 0 - 2 and 0 - 3 are required to be cis and that energy considerations relating to the anomeric effect would dictate the configuration at C-2’. Milder conditions yielded a-L-Sorf-l,2’ :2,1’-P-~-Sorf(l4). OH
HO
220
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
Anhydrous HF has been used to produce mixed dianhydrides of D-fructose and D- or ~-sorbose.'~ The formation of these compounds was used to illustrate steric and electronic effects in the formation of dihexulose dianhydrides, which are covered in more detail later in this chapter. Mixed dianhydrides of glucose and fructose are formed by treating ~-O-a-D-g~ucopyranosy~-D-fructose with anhydrous HF or pyridinium poly(hydrogen fluoride).85P-D-FIx~ 1 ,I ' :2,2'-a-~Glcp (16) and P-D-Frup-1,l' :2,2'-a-~-Glcp(17) were formed in a ratio that varied according to the rigor of the conditions. Longer reaction times and higher proportions of HF favored the latter compound, which is the thermodynamic product.
16 OH
I
2. Spirodioxanyl Pseudo-oligosaccharides This term was used by Defaye and Garcia Fernhndezs6 to describe oligosaccharides that consist of variously glycosylated di-D-fructose dianhydrides. These have been formed e n z y m i ~ a l l y ~and ' * ~also ~ isolated from the products of the citric acid-catalyzed condensation of p a l a t i n ~ s e .Defaye ~~ and Garcia Fernhndez were able to produce and characterize an entire series of these compounds by treating the glycosylfructoses palatinose, leucrose, maltulose, turanose, and lactulose with pyridinium poly(hydrogen fluoride).88The products obtained, in every instance, consisted of a variety of di-D-fructose dianhydrides di-, or in some cases, mono-substituted at the appropriate positions by glucose or galactose. The nature and proportions of the various di-D-fructose dianhydride moieties formed reflected the conditions used and their relative stabilities. In this case, as in Ref, 86, which is covered next, liquid chromatography was used to
DIHEXULOSE DIANHYDRIDES
22 1
confirm quantitative data obtained from NMR spectroscopy. Some of the pseudotetrasaccharides formed in Ref. 88 have been produced on a preparative scale by using anhydrous HEx6 Pseudotrisaccharides were also formed by the cross-condensation of glycosylfructoses with fructose, and mixed pseudotetrasaccharides by the condensation of different glycosylfructoses. The properties of the glycosylated di-D-fructose dianhydrides are summarized in Tables
x-XIII. The treatment of sucrose with anhydrous HF" results in the formation of a complex mixture of pseudooligo- and poly-saccharides up to dp 14, which were detected by fast-atom-bombardment mass spectrometry (FABMS). Some of the smaller products were isolated and identified by comparison with the known compounds prepared86,Rx a-~-Fmf-1,2' :2,l '-p-~-Frup(l),either free or variously glucosylated, was a major product, and this is in accord with the known stability of the compound. The mechanism of formation of the products in the case of sucrose involves preliminary condensation of two fructose residues. The resultant dianhydride is then glucosylated by glucopyranosyl cation." The characterization of this type of compound was an important step because it has permitted an increased understanding of the chemical nature of caramels.
3. Protonic Activation with Acids Other than HF As indicated in Section 111, the early work on di-D-fructose dianhydrides involved treatment with acids at low temperature. Subsequently, the treatment of D-fructose and L-sorbose with concentrated hydrochloric acid and a catalytic amount of a cationic surface-active reagent at 15-20°C was shown to result in the formation of dihexulose dianhydrides." In the case of D-fructose, a-~-Fr~f1,2' :2,l '-p-D-Frup (1) and ~Y-D-FI-uP1,2' :2,l I-p-D-Frup (4) were formed in the ratio 2.5: 1. This constitutes an increase in the proportion of the former compound, as compared with treatment by acid alone.' In the case of L-sorbose, the expected products (based upon previous work22)were a-~-Sorp-1,2' :2,l '-P-LSorp (12), and P-~-Sorf-1,2':2,l '-a-L-Sorp (13). These configurations were assigned by Defaye et al." The authors of Ref. 90 claimed to have obtained a di-pL-sorbopyranosyl I ,2' :2,l '-dianhydride and a-L-sorbofuranose-a-L-sorbopyranose 1,2' :2,l '-dianhydride. The former compound has a unique optical rotation, but the presence of 12 signals in the 13CNMR spectrum and the similarity of the spectrum to that of a-L-Sorp- 1,2' :2, I '-p-L-Sorp casts doubt upon the identification. Additionally, the 'H NMR spectrum of the peracetate reveals non-equivalence of the two sorbose rings. Moreover, the coupling constants measured do not correspond to the 2C, conformation of L-sorbopyranose, which was ascribed to one of the rings. Unfortunately, it is not possible to compare this result directly with the spectrum of per-0-acetyl a-~-Sorp-1,2':2,l '-p-L-Sorp because different solvents were used.
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MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
4. Thermal Activation in the Presence of Acids When D-fructose and L-sorbose are refluxed with aqueous HCl, dihexulose dianhydrides are formed." If the water is replaced by N,N-dimethylformamide, substantially increased yields are obtained and 1,2-linked disaccharides are detected. Higher yields of dianhydrides were obtained from fructose, rather than sorbose, under comparable conditions. Treatment of levan with dilute H,SO, at 60°C yielded92 a-~-Fruf-l,2':2,l '-p-~-Fruf ( 5 ) . Presumably, any products that contain 2,6-linkages with large central rings would rapidly isomerize to the more stable 1,2-linked product. Thermal activation of sucrose and inulin in the presence of citric acid?3 and sucrose in the presence of acetic94acid, yields caramels containing, among other products, di-D-fructose dianhydrides and glycosylated difructose dianhydrides, as described in Section V.6). Similarly, the thermal treatment of 6 - 0 - a - ~ - g l u copyranosyl-D-fructofuranose (palatinose) in the presence of citric acidx7 has been shown to produce appreciable proportions of glucosylated di-D-fructose dianhydrides.
5. Thermal Activation without Acids Di-D-fructose dianhydrides have resulted from the thermal activation of i n ~ l i nand ~ ~fructose,g6 as described in section VI3.
6. The Chemical Nature of Caramels Caramels have been reviewed recently in this series.97They are formed by the thermal treatment of sugars, either dry or in concentrated aqueous solution, with or without additives, such as acetic acid or ammonium hydroxide. Caramels are used extensively in the food industry to impart color and flavor. Although the volatile components of caramel have been well characterized, much less is known about the higher molecular-weight component^.'^ A variety of disaccharides, including some di-D-fructose dianhydrides, were isolated from a low molecular-weight fraction of caramel by Tschiersky and Baltes." Although the precise structures of the dianhydrides were not given, the electron-impact mass spectrum of the per-0-methylated derivative of one of these indicates that it is a difructofuranose dianhydride.95s9x Thermal treatment of anhydrous sucrose or inulin acidified with citric acids3 yielded caramels containing monosaccharides and oligomers (predominantly dianhydrides) and higher oligomers derived by the addition of glycosyl residues to dianhydrides. Thermospray liquid chromatography -mass spectrometry (LCMS) of the oligomer fractions of the sucrose caramel indicated two molecular ions, in analogy to Ref. 94 (see later). The major ion in each fraction corre-
DIHEXULOSE DIANHYDRIDES
223
sponded to molecules formed by the successive addition of glycosyl residues, commencing with a dianhydride. The minor ion corresponded to molecules formed from purely singly linked glycosyl residues. Thermospray LC-MS of the inulin caramel oligomer fractions showed only molecular ions corresponding to molecules initiated from dianhydrides. From the inulin and sucrose caramels, 13 dianhydrides were isolated and ~haracterized.’~ The following dianhydrides were present in differing proportions in both inulin and sucrose caramels: a - ~ - F w f l , 2 ’:2,l’-P-~-Fruf(S),&-DFruf-1,2’ :2,1’-a-~-Fruf (formerly assigned as the P,P anomers2), P-D-Fruf1,2’ :2,l ’ - p - ~ - F r ~ f(a new compound), a-~-Fruf-1,2’:2,3’-P-~-Fruf ( 6 ) , P-~-Fruf-l,2’:2,3’-p-~-Fruf (2), ~ - D - F I I ,,2’ I ~:-2,1’-P-~-Frup ~ (I), p-~-Fruf1,2’ :2,1 ’-P-D-Frup, P-D-Fruf- 1,2‘ : 2,l ‘ - a - ~ - F m pa-~-Fruf, 1,2’ :2,1 ’-a-~-Frup, P-~-Fruf-2,1’:3,2’-a-~-Frup, P-~-Fruf-2,1’:3,2’-P-~-Frup (9), a - ~ - F m p 1,2’:2,l ’-p-D-Frup (4). A g1ucose:fructose dianhydride (a-~-Fmf-l,l’:2,2’-aD - G ~ c was ~ ) isolated from the sucrose caramel, but was not found in inulin ~aramel.’~ Trimers formed by the addition of glucopyranosyl or glucofuranosyl residues to a-D-Fruf- 1,2’ :2,l ’-P-D-Fruf ( 5 ) were identified in sucrose ~ a r a m e l , ’ ~ and a trimer, formed by addition of fructopyranosyl residue to the same dianhydride, was isolated from inulin caramel. Di-D-fructose dianhydrides have also been isolated99 from commercial chicory, which is used as an additive for coffee or in coffee substitutes. Chicory is obtained by roasting the roots of chicory (Cichorium sp.), a member of the Compositae, which contains inulin (in its roots) as a storage polysaccharide. Sucrose caramels have been produced under anhydrous thermal conditions that are designed to maximize the content of fructose-rich oligosaccharides.’”- lo* These “sucrose thermal oligosaccharide caramels” (STOC) have been tested in animals as a nutritional supplement. Improved weight gains and feed conversion, and increased levels of bifidobacteria (see section VIII) were observed in broiler chickens that were fed this ~upplement.”~ The composition of the non-volatile component of a commercial caramel formed from sucrose (with acetic acid as additive) has been almost completely dete~mined.’~ Two series of ions observed in FABMS indicated the presence of two series of compounds. The first series consists of glucooligosaccharides of dp 3-8 and the second consists of pseudo-oligosaccharides formed by the addition of 1 -6 glucosyl groups to di-D-fructose dianhydrides. Interestingly, the conditions under which this caramel was made results in extensive incorporation of glucose into oligomers, whereas the STOC just is prepared under conditions designed to limit the further reaction of glucose, hence, to maximize the content of high-fructose oligosaccharides in the caramel. As a result, the STOC contains about 40% (by weight) of unreacted glucose. Thus, the conditions under which the caramel is made are likely to affect its nutritional properties.
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MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
VI.
CONFORMATIONAL ENERGIES IN DIHEXULOSE DIANHYDRIDES AND THE CONTROL OF PRODUCT DISTRIBUTIONS
1. Electronic Control of Conformation Spiroketals based upon such structures as I ,7-dioxaspiro[5.5]undecane(IS), occur frequently in natural products. Accordingly, an extensive amount of literature relates to the isolation and total synthesis of this type of compound. This literature was reviewediMin 1989. The authors of Ref. 104 listed three factors that influence conformational preferences in these systems. They are ( I ) steric influences, (2) anomeric and related effects, and ( 3 ) intramolecular hydrogen bonding and other chelation effects.
18 The anomeric effect'"' describes the tendency of electronegative substituents to favor the axial disposition when attached to the anomeric carbon atom of a pyranose ring. The exo-anomeric effectIo6describes the tendency for the aglycone to adopt a conformation so that there is a gauche relationship between the C-2-0-6 bond and the 0-2-C-1' bond when viewed along the C-2-0-2 bond, Fig. 1 (in the whole of this section, the anomeric effects are described in terms of dipyranose 1,%-linkeddianhydrides). Both of these conformational tendencies have the effect of placing a lone pair of electrons on oxygen (either 0-6 or 0-2) antiperiplanar to the bond between C-2 and the other oxygen atom (namely 0-2 or 0-6). A number of suggestions have been made as to the origin of these effects, but the most generally accepted today was originally proposed by AltonaIo7and refined by Wolfe et ~ 1 . ' ' ~The latter have suggested that these effects be viewed in terms of stabilizing orbital interaction energy. They have shown, using perturbational molecular-orbital (PMO) calculations, that both the anomeric and exoanomeric effects can be predicted in terms of lone-pair-antibonding (n-u*) interactions between the n lone-pair of 0-6 or 0-2 and the u* orbital of the bond between C-2 and the other oxygen atom (namely, 0 - 2 or 0-6). Thus, both anomeric and exo-anomeric effects have fundamentally the same origin. Praly and Lemieuxio9defined a total anomeric effect (AA) that has an endo(from 0-6) and an exo- (from 0-2) component. In the case of the equatorial
DIHEXULOSE DIANHYDRIDES
FIG.1 .-The
225
exo-anomeric effect in 1.2-linked dipyranose dianhydrides
anomer, the exo-effect (exo-A,) predominates the endo-effect (endo-A,) is negligible. In the case of the axial anomer, the exo-Aaand endo-Aa compete. The total anomeric effect is defined as: AA = (endo-A,+exo-A,) - (endo-Aa+exo-Aa) and the total effect thus varies according to these four individual components. Booth el d."" in their study of 2-substituted tetrahydropyrans, found support for the idea that the exo- and endo-effects are competitive. Nevertheless, Deslongchamps and co-workers" had previously used a co-operative effect to predict successfully the stable conformations, product distributions, and outcomes of isomerization of compound 18 and several of its derivatives. Jarvis"* argued that the two effects are reinforcing because each effect renders the 0 atom more electron-withdrawing for the other. Numerous literature reference^'"^ attest to the fact that the naturally occurring spiroketals and many synthetic products adopt conformations in which the anomeric effects are maximized and the steric effects are minimized. However, in some such compounds, the steric effects of bulky substituents and diaxial interactions can result in a conformation in which the anomeric effect cannot operate. that described the In 1991, an important paper was published by Bock et steric and electronic effects on the formation of the dispiroketal dihexulose dianhydrides. The authors described the conformation of six dihexulose dianhydrides, as determined by X-ray crystallography or NMR spectroscopy. They concluded that these conformations are dictated by the anomeric and exo-anomeric effects. Thus, the dihexulose dianhydrides are disposed to adopt conformations that permit operation of these effects-even if this results in the dioxane ring having a boat conformation or all three substituents on one pyranose ring being axial. In the case of the dihexulose dianhydrides containing three spiro-linked rings, it is perhaps inappropriate to use the terms endo- and exo- without any fixed point of reference-especially because both effects have the same origin. An appreciation of the outcome of these electronic effects can be obtained by taking the 1,4-dioxane ring as the point of reference. This ring adopts a conformation
226
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
FIG.2.-Conformations of the 1,4-dioxane ring with ( a ) differing and ( b )the same anomeric configurations of the glycose residues
so that 0-6 and 0-6' (or 0-5 and 0-5' in the case of difuranose dianhydrides) are axially disposed. For the 1,2-1inked dianhydrides, this conformation is a boat when the two anomeric configurations are the same, and a chair when they differ (Fig. 2). In dipyranose dianhydrides, the hexulopyranose rings, in turn, adopt conformations, which result in the gauche relationship just described. In practice, because of restricted rotation in the pyranose ring, this results in a chair conformation with a 0 - 2 or 0-2' axial. This results in an antiperiplanar relationship between the n lone-pair on all four oxygen atoms and the appropriate C-0 bonds. Rapid interchange between two chair forms of the 1,Cdioxane ring has been suggested as an alternative to the boat form in s o l ~ t i o nHowever, . ~ ~ ~ ~ ~ ~ ~ ~ boat forms of this ring have been found in crystal structures of P-D-FI-uP1,2' :2,l ' - p - ~ - F r u p , * ~and . I ~ ~a study of complexation of this compound with metals also indicated a boat conformation in solution."3 In either chair form of the dioxane ring, one of the 0-6 atoms is equatorially disposed. This permits the operation of only one of the (n-c*) stabilizing orbital interactions, namely, the one involving the n lone-pair on 0-6 at that spiro center. Molecular-mechanics calculations for p-D-Fmp-1,2' :2,l ' - p - ~ - F r u pindicate ~~ that the most stable conformation, with the 1,4-dioxane ring in a boat form, lies 11 M/mol. below the two chair conformations, which are of nearly equal energy. This energy difference is enough to ensure that the boat form of the dioxane ring is the only conformation present. In these c a l c ~ l a t i o n both s ~ ~ boat conformations were found to be distorted. Trans-ring interactions might be minimized by distortion. In free 1,bdioxane, the Cremer and Poplel l4 puckering parameters calculated29are 90 and 38.6", respectively, for 8 and +. Thus, 1P-dioxane has a conformation midway between a boat (0 = 90", = 0') and a skew boat (8 = 90", = 90'). The measured puckering parameters for the 1,Cdioxane ring of p - ~ - F r ~1,2' p - :2,l I -
+
+
DIHEXULOSE DIANHYDRIDES
227
P-D-Fxu~ are 0 = 87.6" and c$ = 8.6" (for a half-boat 0 = 45",4 = 0"); thus, there is less twisting and more flattening of the ring than in free 1,4-dioxane. Intramolecular hydrogen-bonds can increase the stability of certain conformations. For example, dianhydrides that contain P-L-Sorp or a-D-Frup in the 'C2 conformation have the C-4 hydroxyl group in a 1,3-diaxial relationship with 0-2, which permits the formation of an intramolecular hydrogen bond. This might, in part, offset the destabilizing influence of three or two axial substituents, respectively. This effect is decreased in hydrogen-bonding solvents. Electronic effects could also influence the conformations of dianhydrides that contain furanosyl moieties. The dioxane ring will have 0-5 and 0-5' axial and 0 - 2 and 0-2' will tend to favor a quasi-axial ~ r i e n t a t i o n .A~ ~p-1,2-linked fructofuranosyl moiety will have 0 - 2 and 0 - 3 unfavorably eclipsed in certain conformations,26 which results in skew conformations being favored over conformations in which C-2 and C-3 occupy the same plane. Lemieux and NagarajanZ4commented upon the degree of conformational rigidity in the a-fructofuranoside ring of a-D-Fruf-1,2' :2,l '-p-~-Fmf(5), which resulted in resistance to periodate oxidation. French et al.' l 5 have modeled di(3-deoxy-~-glycero-pentulose) 1,2' :2,l'-dianhydride (19), an analogue for a-~-Fruf-1,2':2,l '-p-~-Fmf.A crystal structure of this compound showed the dioxane ring in a chair conformation with both C-2-0-5 bonds axial. The A(a-fructose) and B(P-fructose) furanose rings had the 3E and Eo conformations, respectively. Thermal motion in the crystal indicated that the B ring was more flexible than the A ring. The results of modelling were in excellent agreement with the crystal structure for both furanose rings.
OH 19 When the results of modelling were compared with the NMR data of solutions, a greater discrepancy was observed in the case of the B ring than for the A ring. Because NMR data represents a time average of solution conformations, this result again indicates a greater range of flexibility for the B ring. The decomposition of the torsional-energy components revealed that the difference in the flexibility of the two rings arises primarily from the torsional-angle energy of the C-2-0-5 bond.
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MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
In anhydrous HF, the presence of 2,3-linkages is associated with increased rigor of reaction c o n d i t i ~ n s , ~indicating ' ~ ~ ~ ~ ~that ~ compounds containing this linkage are thermodynamically more stable. Results of acid hydrolysis (section VI.4) support the conclusion that these are more-stable structures. This apparent stability is evident, despite the conformational constraints inherent in this type of linkage. French and Tran'I6 have calculated, using molecular mechanics, the energies of the various conformers of a-and P-fructofuranose (Fruf) residues. The measured conformations of a variety of Fruf-containing compounds fell close to the calculated minimum. However, notable exceptions were observed for the residues in the two difructose anhydrides containing 2,3-linkages [@-D-Fruf 1,2' :2,3'-P-~-Fruf (2) and a-~-Fruf-1,2':2,3'-P-~-Fruf (6)]. It was considered that the inclusion of 0-2' and 0-3' in the dioxane ring would result in significant conformational constraint. To ascertain the extent of this effect, these compounds were optimized as the dimer and as the individual Frufresidues. The 1,2linked @-residueshowed little difference between the results of optimization, as a dimer or individually. Its deformation was therefore attributed to the crystalline environment. In contrast, the 2,3-linked residues showed considerable differences between minima, as the dimer and as the individual residue, indicating that conformation is indeed constrained by chemical structure.
2. Energetic Outcomes of Conformational Rigidity
A combination of stabilization (caused by the anomeric effect) and destabilization (caused by steric interactions) means that, in spirocyclizations and isomerizations, the possible products have a range of conformational energies. In the case of the spiroketals, this often means'04,''' that one product predominates under thermodynamic conditions. This property has been used in syntheses (see Ref. 117). Stereoelectronic considerations also dictate the relative stabilities of the dihexulose dianhydrides. A boat conformation in the dioxane ring, or the presence of axial substituents, might represent the lowest energy conformation for an individual isomer,29 but this minimum will be higher than the minimum for an isomer without such interactions. This concept has been used to predictx4 the high yields, which were subsequently obtained, of a-D-Sorp-1,2' :2, I'-cY-LSorp, which has all three rings in chair conformations and all substituents equatonal. It has also been used to explain the proportions of the different components of product m i ~ t ~ r e ~ . ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3. Thermodynamic Versus Kinetic Control of Product Distributions The products of the dimerization of 1,6-dihydroxy-2-he~anone"~ are the simplest models for the dihexulose dianhydrides. Under thermodynamic conditions, the isomer (20) was the sole product. Under kinetic conditions, compounds 20 and 21 are formed as a 1: 1 mixture. Whereas 20 has the conformation illus-
DIHEXULOSE DIANHYDRIDES
229
trated, 21 was claimed to undergo rapid interconversion between two chair forms of the 1,4-dioxane ring. Under acidic conditions, 21 rapidly isomerized to 20. The origin of the greater stability of 20 can readily be explained on the basis of the electronic effects covered here.
21 Variations in the proportions of the different components of product mixtures are observed in reactions that involve anhydrous and in pyridinium poly(hydrogen fluoride).86These variations can also be explained in terms of kinetic and thermodynamic control. Thus, less stable, but more rapidly formed, dianhydrides isomerize under thermodynamic conditions to give more-stable products. It has also been noted that the starting isomeric forms of the ketose influence the kinetic outcome of the reaction.' l 9 When glycosylfructoses are treated with pyridinium poly(hydrogen fluoride)?' under conditions that favor the kinetic product (low temperature, short reaction times, and a decrease in the proportion of HF), p-~-Fruf1,2':2,1'-p-~-Fruf (now assigned as WD-FI-U~ 1,2' :2,1 '-a-~-Fruf'~)and a-~-Fmp-l,2':2,1 '-p-~-Frup(4) derivatives were observed. The former of these two groups of compounds is then readily isomerized (still under kinetic conditions) to produce the more-stable a-DFruf 1,2' :2,1 ' - p - ~ - F r ~(5) f derivatives. Under thermodynamic conditions, a-DFruf l,2': 2,1 '-p-~-Fr~p (1) and p-~-Frup-1,2' :2,1'-p-~-Frupderivatives were observed; these are considered to be final thermodynamic products. These results are in accord with those observed for the treatment of D-fIUCtOSe and L-sorbose with anhydrous HF.3'*x0 The three axially disposed substituents in a-~-Frup-l,'2':2,1'-p-DFrup (4) were postulated as being an energetically unfavorable arrangement. Presumably, the increase in energy caused by the presence of two axial substituents in one pyranose ring and one in the other is greater than the effect of a boat conformation in the dioxane ring and a single axial substituent in each ring, as occurs in p-DFrup-l,2':2,1'-p-~-Frup. Glycosyl derivatives of p-~-Fmf-I ,2' :2,3'-p-~-Fruf (2) are also considered to be thermodynamic products?' as are a-~-SoIJs1,2':2,3'-a-~Sorfs2(15) and other 2,3-linked dianhydride~.~~." However, as indicated earlier, the reasons for this are not readily rationalized on steric and electronic grounds?' it has been claimedxsthat the position of the glycosyl substituents has minimal influence in the foregoing energetic considerations, apart from structures that are derived HF"',80*82384385
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MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
from 3-O-a-~-glucopyranosyl-~-fructose (turanose), in which a stabilization of the a# difuranose kinetic product has been observed. Treatment of the glycosylfructoses with anhydrous HFS6 produced similar products as did treatment with pyridinium poly(hydrogen fluoride). It was observed that cleavage of the glucose-fructose bond, which had occurred in pyridinium poly(hydrogen fluoride),88did not occur in anhydrous HES6This difference was ascribed to decreased protonating ability of the HF because of its involvement in hydrogen bonding with the sugar substrate, which is present in high concentration. Diminution of this concentration resulted in cleavage or isomerization of the glucosidic bond. In the earlier experiments with pyridinium poly(hydrogen fluoride),@lower concentrations of sugar had been used. Experiments with an 80: 20 mixture of HF and pyridine resulted, under more drastic conditions, in the cleavage of one of the glucose-fructose bonds, yielding mono-glucosyl dianhydrides. In three out of the five glucosylfructoses, no more isomerization of the di-D-fructose dianhydride portion of the molecule was observed in anhydrous HF86than in 70: 30 HF-pyridine." For the other two isomers, the extent of isomerization was equivalent to that observed in 80:20 HF-pyridine." This result might also be attributed to the decreased protonating power of the anhydrous HF. The compositions of product mixtures arising from thermal treatments deviate from the patterns observed in the relatively low-temperature treatments with HF. Pyrolysis of inulin9' yielded a caramel-like material that contained 26% of di-Dfructose dianhydrides and a continuum of oligomers and polymers, of which at least some were spirodioxanyl pseudo-oligosaccharides, having fructosyl groups attached. GLC of the per(trimethylsily1) ethers of the disaccharide fraction revealed that 75% of this fraction consists of a-~-Fruf-l,2':2,l '-p-~-Fruf(5),a - ~ Fruf-1,2' :2,3'-P-~-Fruf (6), and p-~-Fruf-1,2':2,3'-p-~-Fruf (2) in the ratio 2 :2 : 1. Other peaks observed in the GLC trace had mass spectra consistent with difructofuranose dianhydride~.~~.~' Only traces of furanose-pyranose dianhydrides were observed. The product distribution of the di-D-fructose dianhydrides obtained by mild hydrolysis of a trisaccharide fraction was almost identical with that of the disaccharide fraction. In terms of what has been previously covered in relation to HF-generated dianhydrides, this is an unusual product distribution because it contains a putative kinetic product [a-~-Fruf-1,2' :2,l '-p-~-Fruf( 5 ) ] as a major constituent, despite the high temperature of reaction (200°C). The two other major constituents are conformationally strained structures116of which one, a-~-Fmf-1,2' :2,3'-p-~-Fruf,has previously been observed (as the diglucosyl analogue) only in minor amounts86.88 in the protonic activation of palatinose (6-~-a-~-glucopyranosyl-D-fructofuranose). The other, p-~-Fruf-1,2' :2,3'-p-~Fruf, is considered to be a thermodynamic product.86*88 The authors of Ref. 95 proposed a mechanism whereby these three products could arise directly from inulin without any isomerization.
DIHEXULOSE DIANHYDRIDES
23 1
Similar anomalous distributions are observed in other thermal product mixtures. A commercial soft caramel made by heating sucrose and 0.1 % acetic acid to 160°C contained 18% of a mixture of di-D-fructose dianhydride~.’~ P-D-Fruf1,2’ :2,1’-p-~-Fruf(now assigned as a-~-Fruf1,2’:2,1’-a-D-Frufs’), a-~-Fruf 1,2’:2,1’-P-~-FrUf(5), a-D-Frup-1,2’ :2,1’-P-~-Frup(4), a-D-Fruf-l,2’:2,I’-PD-Frup (I), and P-~-Fruf-1,2’:2,3‘-P-~-Fruf (2) were found in the ratio 4 : 12 : 1 :6 :2. The first three of these, constituting 68% of the mixture, are considered to be kinetic products. The authors commented on this, but did not offer any explanation. Notice, however, that the preparation of such commercial caramels commences with heating of an acidic aqueous solution of sucrose, which almost certainly results in hydrolysis. Hence, the final dianhydrides are probably derived from the reaction of fructose, rather than sucrose. Tschiersky and B a l t e ~prepared ~~ di-D-fructose dianhydrides by heating fructose. Mass spectra of the permethyl ethers were obtained. Although the dianhydrides were of unknown structure, examination of the spectra indicate that all are difuranose dianhydrides (mlz 101 as the base peak, and low intensities of the ions miz 88 and 277) and at least one is reminiscent of a 2,3-linked difuranose structure (relatively intense mlz 363 [M - 45]+).95,y8 The non-precipitable (that is, lower molecular weight) component of a product from thermolysis ( 170”C, 80 min.) of anhydrous amorphous sucrose acidified with 1% citric acid contains 19% disaccharides, predominantly diD-fructose dianhydride~.’~Only two of these were identified, namely a-D-Fruf1,2‘:2,1’-P-~-Fruf(5) and a-D-Fruf-I,2’:2,1’-P-~-Frup (1) in the ratio 1 : 1. This result can be compared with the ratio 2 : 1 for the commercial caramel.94 These results indicate that, during thermolyses of fructose-containing saccharides, di-D-fructose dianhydrides are formed readily, but subsequent isomerization is extremely slow-even in the presence of added acid. However, under these conditions, the protonating power of any acid is moot. At the high temperatures used, residual water would be driven off rapidly, unless the reaction vessel is pressurized; therefore, reaction occurs in the anhydrous melt. It is presumably protonation of one of the ring oxygen atoms in the dianhydrides that constitutes the first step in isomerization, followed by scission of a C - 0 bond to yield one of the oxocarbenium ion intermediates postulated in Refs. 31 and 80. Such ions have also been postulated as intermediates in the isomerization of spiroketals to a more-stable product. This latter isomerization can be extremely facile;lWdilute aqueous acid,’20or non-aqueous Lewis-acid conditionsI2’ have been used to effect such transformations. It might be pertinent to consider the basis of the extremely facile isomerization in anhydrous HF or pyridinium poly(hydrogen fluoride). HF is an extremely strong proton donor, but it is also a potent fluorinating agent. It is highly probable that the postulated cationic intermediates in these isomerizations are fluorinated and serve as reactive intermediates in the same way as the fructofuranosyl
-
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MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
or sorbofuranosyl cationic intermediates in the original formation of the dianhydrides.”*R0,82 This would lower the energy of the intermediates, and thereby facilitate the isomerization. 4. Acid Hydrolysis of Di-D-fructoseDianhydrides and Their Per-0-methyl Derivatives From almost their first discovery, the stability to acid of these compounds has been noted. a-~-Fruf-1,2‘ :2,1’-p-~-Fruf(S)was found12to be 25 times as resistant to acid hydrolysis as inulin. This observation was rationalized by the presence of the 1,4-dioxane ~ i n g . ’ ~Moreover, ”~ the various dianhydrides were not all equally resistant to acid. At 60°C in N H,SO,, the half-period of hydrolysis of a~-Fruf-1,2’:2,1‘-P-D-Fruf (5)was 463 minutes, as compared with 1071 minutes for a-~-Frup-1,2’:2,l ’-p-D-Fmp (4).6”2 In a 0.2N acid at lOO”C, a-~-Fruf1,2’:2,1’-P-D-Fruf (5) was 84.3% hydrolyzed in 100 minutes,I2*as compared with 64% in 100 minutes for p-~-Fmf-1,2’:2,3’-P-~-Fruf(2) and 81% in 110 minutes for a-~-Fruf-l,2’:2,3’-p-~-Fmf’ (6). Similar observations have been made for the hexamethyl ethers. Thus, conditions that cause almost complete hy(4) and a-~-Fmfdrolysis of per-0-methylated a- ~ - F m p -,2‘ l :2,l ’-p-~-Frup 1,2’:2,1’-P-~-Fruf (5) result in only -50% hydrolysis of the a-~-Fruf1,2’:2,l’-p-D-Frup (I) d er i v at i ~ e , 9 ~of* ’the ~ ~ P-~-Fruf-1,2’:2,3’-p-~-Fruf(2), and of the a-~-Fmf-1,2’:2,3’-P-~-Fruf(6) derivative^.^^^" Permethylated p-DFruf-2,l’ :3,2’-P-~-Frupproved to be extremely resistant to hydrolysis, as compared with the other dianhydride~;’~ a two-fold increase in acid concentration and a 5” increase in temperature being required to bring about only a partial hydrolysis. Deslongchamp~’~~ has concluded that hydrolysis of a glycosidic bond must proceed through a conformation in which the lone pair of the ring oxygen is antiperiplanar to the C-0 bond that undergoes scission. For the di-o-fructose dianhydrides, in which the conformations are always in accord with the anomeric effect, this means that hydrolysis occurs from the ground-state conformation. Thus, the relative rates of hydrolysis can be rationalized by the same arguments used to explain product distributions.
VII. DI-D-FRUCTOSE DIANHYDRIDES AND INDUSTRY Conditions of high temperature and/or low pH, or conditions that are strongly dehydrating, can occur during the industrial processing of sucrose and fructose. Under these conditions, fructose’25or sucrose can react to produce dianhydrides. Greater than 10% conversion of fructose has been 0 b ~ e r v e d .Di-D-fructose l~~ dianhydrides can interfere with the monitoring of such processes as the inversion of sucrose.126A method has been described for the identification of seven di-Dfructose dianhydrides in sucrose-processing mixtures using infrared spec-
DIHEXULOSE DIANHYDRIDES
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t r o ~ c o p y . 'Inhibition ~~ of crystal growth in fructose has been observed in the presence of di-D-fructose dianhydride~,'~~.'~~~'~~ and it has been postulated that these compounds become incorporated into the crystal, thereby preventing further g r o ~ t h . ' Chu ~ ~ ,and ~ ~Berglund2' ~ have reported on the kinetics on the formation of IX-D-FIIIP-1,2' :2,l ' - p - ~ - F r ~(4), p IX-D-FIU~-~ ,2' :2,1 '-p-~-Fr~p (l), p - ~ - F r ~1,2' f - :2,1 ' - p - ~ - F r ~ pand , p-D-Frup- 1,2' :2,1 '-p-D-Frup (diheterolevulosans I-IV) under fructose crystallization conditions (65-95% aqueous fructose, pH 2.65-5.90, 30-60°C). The identity of the first two was ascertained by comparison with standards, but the putative identities of the second two were assumed. P-D-Frup- 1,2' : 2,l '-p-~-Fmpand p - ~ - F r ~1,2' f - :2,1 '-p-~-Frupformed rapidly and their concentrations, the former greater than the latter, then levelled off, showing a slight decline over the duration of the reaction (14 days). The other two compounds formed more slowly, increasing over the entire reaction period. This behavior was attributed to the fact that the p-D-fructopyranose form predominates in aqueous solutions of fructose, even though mutarotation might be expected to be very rapid under these conditions. The conclusion is also contrary to the results observed with HF,31388 in which the a,P-dipyranose isomer is considered to be the kinetic and the @,P-dipyranoseis the thermodynamic product. A kinetic model was proposed2' in which all four compounds formed directly and irreversibly by condensation of two fructose molecules, with no isomerization. Disappearance of fructose was claimed to follow second-order kinetics, although the data could only be fitted by a two-section broken line. This was explained in terms of a supposed, but unlikely, selective inhibition of the formation of the two most rapidly formed isomers because of solvation of fructose when the fructose concentration fell below a critical point. VIII.
USES OF
DI-D-FRUCTOSE DIANHYDRIDES
1. Di-D-fructose Dianhydrides and Nutrition
In 1993, the di-D-fructose dianhydrides were summarized as being of "little, if any, commercial i mp~rt a nc e ."~~ However, a search of the literature reveals an appreciable number of patents issued since 1989 for the manufacture of these compounds. These include enzymic methods for the production of individual dianhydrides (Ref. 130) or methods of production of mixtures using anhydrous HF or pyridinium poly(hydrogen fluoride) (see Ref. 131). Most cite the di-D-fructose dianhydrides as low-calorie sweetening agents (Ref. 132), and some claim anticariogenic properties (Refs. 132 and 133). Di-D-fructose dianhydrides have been claimed to promote the growth of bifidobacteria in ~ i t r 0 . IBifidohacterium ~~ spp. are found in the large intestines of most vertebrate^.'^^ The benefits attributed to the presence of a healthy population of bifidobacteria in the gut include: inhibition of carcin~genesis,'~~ suppression of putrefactive substance^,'^^ lowering of blood pressure and blood
234
MERLYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
cholesterol in hypercholesterolemic s u b j e ~ t s , ' ~ synthesis ' * ~ ~ ~ of B-complex vitamins and/or their preservation from decomposition by other ba~teria,'~' and inhibition of unfavorable bacteria, such as Clostridium peqringens and Escherichia coli.'40*i4i E. coli is a common cause of infant diarrhea, and populations of Sifdobacterium infantis are found to be lower in bottle-fed than in breast-fed Administration of antibiotics can also suppress bifidobacteria populat i o n ~ .Bifidobacteria '~~ can be included as probiotics in humani43and animaliu food. a-~-Fruf 1,2':2,3'-p-~-Fruf has been claimed to improve rate of weight gain and feed efficiency, and decrease lipid content in f0w1.I~~ These effects have been more substantively demonstrated, and increased bifidobacteria populations also demonstrated in another study in fowl.'O3 In this study, a specially prepared sucrose caramel was used as a feed supplement. This caramelization process was designed to maximize the presence of a continuum of predominantly fructosyl oligosaccharides, including and incorporating difructose dianhydrides.loo- lo* These indications that di-D-fructose dianhydrides might act to promote the growth of bifidobacteria, with attendant health benefits, reveal exciting possibilities for the use of these compounds. However, a much greater body of knowledge needs to be accumulated about the possible effects of ingestion of di-Dfructose dianhydrides, aside from the effect on bifidobacteria populations. It has 12':2,3'-P-~-Fruf (6)is not metabolically been d e m ~n s t r ate d'~~ that a-~-Fr~finert, and it affects, at least, fructose metabolism by the liver. Furthermore, the same work showed that this compound is capable of being transported across the cell membrane. This indicates that ingested di-D-fructose dianhydrides might not be restricted to the intestinal lumen.
2. Di-n-Fructose Dianhydrides in Chemical Synthesis The raw materials from which di-D-fructose dianhydrides can be obtained in appreciable yield are readily available from comparatively inexpensive agricultural feedstocks. Thus, these compounds are attractive as chiral-starting materials for chemical synthesis. Their stability to acid and heat, and their relative rigidity, because of the conformational constraints covered here, are also features that might be exploited during syntheses.Il9 A series of variously substituted diD-fructose dianhydrides has been prepared,'" starting from 6,6'-dideoxy-6,6'-dihalosucroses. The properties of these and other derivatives of di-D-fructose dianhydrides are summarized in Tables XIV-XX. Two of these derivatives, 48 and 56, exhibit thermotropic liquid-crystal properties.' I y a-D-Fruf1,2':2,l'-p-~-Frup (1) and a-D-Fruf- 1,2':2,l'-p-~-Fruf (5) have been polymerized to yield hydrophilic ether copolymers. I The latter anhydride has been used as a chiral-starting material for the synthesis of 3,6-anhydro-keto~ - f r u c t o s e , 'which ~ ~ has been proposed as an intermediate in the synthesis of oxaprostaglandins.
DIHEXULOSE DIANHYDRIDES
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ACKNOWLEDGMENTS The authors thank Dr. Jacques Defaye of CNRS and CEA, DCpartement de Recherche Fondamentale sur la Matikre CondensCe/SESAM, Centre d’Etudes de Grenoble for his helpful comments. Financial support was provided by The Sugar Association, Inc.
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260(1994) 1-15. 116. A. D.FrenchandV.Tran,Biopolyrners,29(1990) 1599-1611. 117. C. Iwata, M. Fujita, Y. Moritani, K. Hattori, and T. Imanishi, Tetruhedron Lett., 28 (27) (1987) 3135-3138. 118. W. A. Szarek, 0. R. Martin, R. J. Rafka, and T. S. Cameron, Can. J . Chem., 63 (1985) 1222- 1227. 119. J. M. Garcia Femindez, A. Gadelle, and J. Defaye, Carhohydr. Res., 265 (1994) 249-269. 120. L. Cottier, G. Descotes. M. F.Grenier, and F. Metras Tetrahedron, 37 (1981) 2515-2524. 121. T. Kozluk, L. Cottier, and G. Descotes, Tetrahedron, 37 (1981) 1875- 1880. 122. R. F. Jackson and S. M. Goergen,J. Res. Nat. Bur. Stand., 5 (1930) 733-734. 123. B. Lindberg and B. Wickberg, Acta Chem. Scand.. 7 (1953) 969-973. 124. P. Deslongchamps, in Stereoelectronic Eflects in Organic Chernisfry,Pergamon Press, Oxford ( I 983). 125. K. H. Forsberg, L. Hamalainen, A. J. Melaja, and J. J. Virtanen, U.S. Patent 3883365, (1975). 126. D. E. Rearick and L. J. Olmstead, Proc. Sugar Process, Res. Confi, (1993) 97-107. 127. W.W. Binkley, R. W. Binkley, and D. R. Diehl, lnr. Sugar J., 73 (873) (1971) 259-261. 128. Y. D. Chu, Ph.D. Thesis, Michigan State University, East Lansing, MI, USA, 1988. 129. Y. D. Chu, L. D. Shiau, and K. A. Berglund, J . Cryst. Growth, 97 (1989) 689-696. 130. T. Uchiyama, A. Kamata, and H, Kusano, EP 336376 A2 891011, 1989; Chem. Ahstr., 1990; 112:174852. 131. J. Defaye, J. M. Garcia Femandez, and A. Gadelle, FR 2680788 A1 930305, 1993; Chem. Abstr.. 1993; 119:271615. 132. T. Kondo, T. Katsuragi, and A. Nishimura, JP 03180155 A2 910806 Heisei, 1991; Chem. Ahstr., 1992; 116:82518. 133. T. Kondo and A. Nishimura, JP 03067560 A2 910322 Heisei, 1991; Chem. Ahstr., 1991; 115: 278530. 134. S. Kobayashi, K. Seki, K. Haraguchi, M. Kishimoto, K. Nagata, K. Honbo, K. Kainuma, and M. Kadoma, JP 63269962 A2 881 108 Showa, 1988; Chem. Abstr., 1989; 11156162. 135. T. Mitsuoka and C. Kaneuchi, Am. J . Clin. Nutr., 30 (1977) 1799- 1810. 136. B. S. Reddy and A. Rivenson, Cancer Res., 53 (1993) 3914-3918. 137. H. Hidaka, T. Eida, T. Takizawa, T. Tokunaga, and Y. Tashiro, Bifidohucteria Microfora, 5(1) (1986) 37-50. 138. H. Hidaka and M. Hirayama, Biochem. Soc., Trans., 19 (1991) 561-565. 139. T. Mitsuoka, Intestinal Bacteria and Health, Harcourt, Brace and Jovanovich, Tokyo, Japan (1978). 140. S. A. Ibrahim and A. Bezkorovainy, J. Food Protection, 56(8) (1993) 713-715. 141. M. P. Wilhelm, D. T. Lee, and J. E. Rosenblatt, Eur. J . Clin, Microbiol., 6(3) (1987) 266-270. 142. K. S. Lim, C. S. Huh, andY. J. Baek,J. Dairy Sci., 76 (1993) 2168-2174. 143. H. W. Modler, R. C. McKellar, and M. Yaguchi, Can. Insf. Food Sci. Techno/. J . , 23 (1990) 29-41. 144. Probiotics the Scientific Basis. R. Fuller (Ed.), Chapman & Hall, London, 1992.
DIHEXULOSE DIANHYDRIDES
239
145. T. Katsuragi and A. Nishimura, JP 05168419 A2 930702, Heisei, 1993; Chem. Abstr., 1993, 119: 159111. 146. M. C. 0. Hauly, A. Bracht, R. Beck, and J. D. Fontana, Appl. Biochem. Biotech., 34-35 (1992) 297-308. 147. J. Defaye and J. M. Garcia Fernhndez, Tetrahedron Asymmetry, 5(1 I ) (1994) 2241 -2250. 148. A. K. B. Chiu, M. K. Gurjar, L. Hough, L. V. Sincharoenkul, and A. C. Richardson, Carbohydr. Res., 100 (1982) 247-261. 149. K. h p e k , E. hadova, and P. Sedrnera, Carbohydr: Res.. 205 (1990) 161-171. 150. J. M. Garcia Ferndndez, C. Ortiz Mellet, J. L. JirnCnez Blanco, J. Fuentes Mota, A. Gadelle, A. Coste-Sarguet, and J. Defaye, Car-bohydr.Res., 268(1) (1995) 57-71. 151. J. M. Garcia Fernandez, R. R. Schnelle, and J. Defaye, Tetrahedron Asymmetry, 6(1) (1995) 307-3 12.
TABLE I Dibexulose Dianhydridesand Related Compounds
Trivial Name ~
N
8
IUPAC Name
Proposed Abbreviation
~
Diheterolevulosan I Diheterolevulosan TI Diheterolevulosan III DiheterolevulosanIV
Difructose anhydride I Difructose anhydride I1 Difructose anhydride III Difructose anhydride IV Difructose anhydride V Alliuminoside 2,l' :3,6:3',6'-Trianhydrosucrose
a-D-fructopyranoseP-o-fructopyranose 1,2' :2,1 '-dianhydride a-o-fructofuranose P-D-fructopyranose 1,2' :2.1 '-dianhydride p-D-fructofuranose P-D-fruCtOpyKinoSe 1,2' :2.1 '-dianhydride di-P-D-fructopyranose 1,2' :2,l '-dianhydride a-D-fructofuranosea-D-fructopyranose1,2' :2.1 '-dianhydride p-o-fructofuranose a-D-fructopyranose 1,2' :2,l' dianhydride p-D-fructofuranose a-o-fructopyranose 2.1 ' :3,2'-dianhydride p-D-fructofuranose P-D-fructopyranose 2,l' :3,2'-dianhydride di-a-o-fructofuranose 1.2' :2,l '-dianhydride di-P-D-fructofuranose 1.2' :2.1 '-dianhydride u-o-fructofuranose p-bfructofuranose 1,2' :2,l '-dianhydride di-P-D-fructofuranose 1,2':2,3'-dianhydride a-o-fructofuranose P-D-fruCtOfurarIOse 1,2' :2,3'-dianhydride di-P-o-fructofuranose 2,6' :6,2'-dianhydride a-o-fructofuranose P-D-fructofuranose 1,2' :2,6'-dianhydride ?-D-fruCtOfuranOSe?-D-fruCtOfWanOse2,6' :6,2'-dianhydride 3.6-anhydro-P-D-fructofuranose 3 ' ,6'-anhydro-a-~-glucopyranose 1,2':2,1'-dianhydride
a-~-Frup-1,2':2,1 ' - p - ~ - F r ~ p a-~-Fmf-1,2':2,1'-p-~-Frup P-D-FNf-1,2' :2,1'-P-~-Frllp P-D-Frup-1,2' :2,l '-P-D-Frup a-~-F~~f-l,2':2,1'-a-~-Frup P-o-Fruf-l,2':2,l'-a-~-Frup P-~-FrUf2,1':3,2'-a-~-Fr~p p-D-FrUf2,l' :3 , 2 ' - P - ~ - F v a - ~ - F m f1,2' - :2,1 '-a-D-Fruf P-D-Fruf-1.2' :2,1' - p - ~ - F r ~ f a-D-Fruf-1.2' :2,1'-P-~-Fryf p-~-Fr~f-1,2' :2,3'-p-~-Fruf a-o-Fruf-1,2': 2,3'-p-~-Fruf P-~-Fr~f-2,6' :6,2'-P-D-FrUf a-~-Fmf-1.2' :2,6'-p-~-Fruf ?-0-Fn?f-2,6' :6,2'-?-D-Fr~f :2,1'-(~-D-Gl~p-3'.6' 3,6-P-~-Fr~f-l,2'
2.1 ' :3,6-Dianhydrosucrose 2.1 '-anhydrosucrose
2,3'-Anhydrosucrose
Diheterosorbosan I h)
5
Diheterosorbosan I1
1.2' :2,1'p-D-fruCtOfUranOSe 3',6'-anhydro-a-~-glucopyranose dianhydride p-o-fructofuranose a-o-glucopyranose 1.2' :2.1 '-dianhydride a-o-fructofuranose a-o-glucopyranose 1,l' :2,2'-dianhydride p-o-fructofuranose a-o-glucopyranose 1,l' :2,2'-dianhydride P-o-fructopyranosea-o-glucopyranose 1 , I ' :2.2'-dianhydride p-o-fructofuranose a-o-glucopyranose 2, I ' :3.2'-dianhydride P-D-fruCtOpyranOSea-wsorbopyranose 1,2' :2.1 '-dianhydride P-D-fructopyranose a-L-sorbopyranose 1,2' :2,l '-dianhydride di-a-L-sorbofuranose 1.2' :2,3'-dianhydnde a-1-sorbofuranose a-L-sorbopyranose2, I ' :3,2'-dianhydride di-a-L-sorbopyranose I ,2' :2,l '-dianhydride a-D-sorbopyranose a-L-sorbopyranose 1.2' :2.1 '-dianhydride di-P-L-sorbopyranose 1.2' :2.1 '-dianhydride a-L-sorbopyranosep-L-sorbopyranose 1.2' :2.1 '-dianhydride a-L-sorbofuranose a-L-sorbopyranose 1.2' :2,l '-dianhydride P-L-sorbofuranose a-L-sorbopyranose 1,2' :2.1 '-dianhydride a-L-sorbofuranoseP-L-sorbofuranose 1.2' :2.1 '-dianhydride
P-~-Fruf-1,2':2,1'-a-~-Glcp-3'.6' p-D-FrUf-1,2' :2,1'-a-~-Gkp a-0-hlf-l.1' :2,2'-a-D-Gkp P - 0 - F ~ f - ,I' l :2,2'-a-D-Glcp P-o-Frup-1,I' :2,2'-a-D-Gkp P-0-Fruf-2.1' :3,2'-a-D-Glcp B-o-Frup-1,2' :2,1 '-cY-D-sOrp p-~-Frup-I ,2' :2,1 '-a-L-Sorp a-L-Sorf-l,2' :2,3'-a-L-S0$ a-~-Sorf-2,1':3,2'-a-~-Sorp a-L-Sorp-1,2' :2,1'-a-~-Sorp a-D-SOP-l,2' 2,1 '-a-L-SOlp P-L-Sorp-1.2' :2,1'-p-~-Sorp a-L-Sorp-1,2' :2,1'-p-~-Sorp a-~-SoIf-1,2' :2,l '-a-L-Sorp p-~-Sorf-l,2':2,1'-a-~-Sorp (Y-L-SOrf-I,2':2.1 '-P-L-SOrf
TABLE I1 Optical Rotations and Melting Points of Dihexulose Dianhydrides and Related Compounds
Compound
p-0-Fmp-1.2’: 2,1‘-p-~-Frup :2,1’-a-~-Fmp ~-D-FIu~I,~’ :2,l‘ - a - ~ - F w p-D-Fmf-1,2’ p-D-FNf-2,1’ 3.2‘-a-D-Frup P-D-Fmf-2,l’ 3,2‘-p-~-Fmp a-r)-F~f-l,2’:2,1‘-a-~-F~f
p-~-Fmf-1,2’ :2,1‘-p-~-Fmf a-D-Fmf-1,2’ : 2,1’-p-~-Fruf
[a],(degrees) (T”C,e, solvent)
H,O) -43.22 (18.4.28, -43.49 (18,4.093, H,O) -43.9(19,1.02, H,O) -44 (20.2,Hp) -45.8(18,4,H,O) -40 (20,2, H,O) -39 (28,4, H,O) -39 (2s. 4,H,O) - 179 (29,3.6, H,O) - I83 (20,1.8, H,O) -309 (20.2,H,O) +94.1 (25,1.6, H,O) +4.8(2.1,H,O) - 180 (25.0.5, H,O) -58.5(20,1.03, H,O) -68 (25.0.44, H,O) +93 (20.2.2, H,O) + 114.8(25.6.0,H,O) -53.7(25,5.4, H,O) +26.9 (20,8.45, $0) +30.17(2.32,H,O) +27 (H,O) +26 (30, 1.6, H,O)
Melting Point (”C)
Ref.
266-267 250-270 (decornp.) 270-273 (decornp.) 261-263 (decornp.) 255-256 250-252 (decornp.) 257-259 (decornp.) 255- 258 240-242 (decornp.) 279-281 (decornp.) -
5 5 6 123 8 122 8 9 10
-
11
11 83
-
83 83
206- 207
31
-
83
-
82 83
-
143-145 163-164 158-160
83
12 13 15 10
‘1
p-D-FNf-1,2‘ :2,3‘-p-~-Fr~f a-D-FrUf-1.2‘:2,3’-p-D-FNf P - D - F I u ~ ~:6,2’-p-D-FNf ,~‘ a-D-FNf-1.2‘ :2,6’-P-~-Fmf :6 , 2 ‘ - ? - ~ - F ~ f ?-D-F~f-2,6‘ 3,6-p-O-Fr~f-1,2’:2,1 ‘-a-D-GICp-3‘,6‘ p-D-Fruf-1,2’ : 2.1 ‘-a-~-Glcp-3‘,6’ Cr-D-FrUf-l,l’ :2,2’-(u-D-Gkp P-~-Fmf-l,I :2,2‘-a-D-Glcp P-D-FNP-I,~‘:2,2’-a-D-Gkp p-D-FrUf-2,I’ :3,2’-a-D-Gkp :2,1’-a-D-S0rp P-~-Fr~p-1,2’ P-D-FIuP-1.2‘ :2,1 ’-a-t-Sorp a-L-SO$-12’ :2,3’-a-L-SOrf a-L-So$-2.1 :3,2’-a-~-Sorp a-L-Sorp-1,2’:2.1 ’-a-L-Sorp :2,1’-a-~-Sorp a-~-Sorp-1,2’ p-~-Sorp-1,2‘:2,1’-p-~-Sorp a-~-Sorp-1,2‘:2,1‘-p-~-Sorp a-~-Sorf-l,2’:2,1‘-a-~-Sorp p-~-Sorf-l,2’ :2,1’-a-~-Sorp a-L-Sorf-1,2‘ :2,1’-p-L-sOlf
+ 13.85 (20,8.993, H,O) +14.2(20, 1.01, H,O) + 135.64 (20,7347, H,O) -32 (20, 1.205, H,O) +95.8 (20, 1.13, H,O) -23.8 (20) +54 ( 1, MeOH) + 16 (1, MeOH) +26.8 (25.2.98, H,O) +14.5 (20, 1.1, H,O) +24 (20, 1.1, H,O) +72 (20, 1, H,O) -43 (20, 1.4, H,O) -272 (20,0.6, H,O) -42 (20, 1.2, MeOH) -21.5 (20, 2.6, HZO) -210 (20,0.9, H,O)
-
198 200 162 177-178 201 -203 92 - 93 188-190
263-264 (decornp.) 201-203 210 (decornp.) 194-196
239- 24 1 >320
-107 (20,0.17, H,O) - 11.5 (20, 2.6, H,O)
-11.5 (27,2.6, H,O) - 118 (20.0.5, H,O) - 121 (20,0.40, H20) 0.00 (20, 1, H,O) 0.00 (26, 1, H,O or MeOH) - 11.0 (20, 1.3, H,O)
233-235 249-250 (decornp.) 198-199
189- 190 188-189 198- 200
16 19 16 53 72 33 148 148 83 85 85 149 84 84 82 80 80 84 90 80 22 80 90 80 22 80
U
e
3 X
s
km
244
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
TABLE111 Optical Rotations and Melting Points of Per-0-acetyl Dihexulose Dianhydrides and Related Compounds [a],(degrees)
Per-0-acetyl Derivative of a-D-FNp-1.2’ : ~ , ~ ‘ - P - D - F N ~ a-D-Fmf- I ,2’ :2,l’-p-D-FNp P-o-Fruf-1,2’ :2,1‘ - p - ~ - F r ~ p p - ~ - F ~ p - l ,:2,1 2 ’ ’-p-~-Fmp
P-0-Fruf2.1‘ :3,2’-P-~-Frup a-~-Fmf-1,2‘:2,1 ’-a-D-Fruf a - ~ - F ~ f,2’ - l:2,1 ’-P-D-Fruf
(TT,c, solvent)
Melting Point (“C)
-59.1 (20, 1.02, CHC1,) -59.0 (28, 1, CHCI,) -41.5 (29.4, CHCI,) - 169 (25, I , CHCI,) - 159 (20, 2, CHCI,) - 199 (20,2, CHCI,)
171-173 172.5- 173.5 123-124 135.5-136.5 130.5- 131 268-269 (under sublimation) 269-270 122- 123 117-118 137 (sinters at 125) 123 128 (137 after congealing) I28 137 (sinters at 125) 142- 143 113 98-99 299 (decomp.) 115-116 141 (from ether) 194-195 (from EtOH)
-195 (20, 1.1, CHCI,) -86 (20, 1.4, CHCI,) +119(20.0.3,CHCI,) +0.54 (20,9.98, CHCI,) + 1.5 (2.272, CHC1,) +0.65 (16, 1.5, CHCI,) 0 (25,2, CHC1,)
+0.6 (19.3, CHCI,) -54.9 (20.0.695. CHCI,) P-~-Fmf-2,6’:6,2’-p-~-F11f a-~-Fruu$-1,2’:2,6’-p-~-Fruj‘ +47 (20, 0.40, CHCl,) ? - ~ - F ~ f - 2 , :66’, 2 ’ - ? - ~ - F ~ f -29.3 (20) 3,6-P-~-F~f-1,2‘ :2,1’-a-D-Gkp-3‘.6’ +68 ( 1 , CHCl,) +39 ( 1, CHCI,) P-D-Fruf-1.2’ :2,1’-a-o-Glcp-3’.6‘ P-~-F~f-I,2’:2,1’-a-~-Glcp +79 (1, CHC1,) P-D-FrufI,l‘:2,2’-a-D-GlCp +26 (20, 1.1. CHCI,) P-D-FNP- 1.1 ’ :2,2’-au-D-Gkp p-D-FNf-2,I ’ :3,2’-(Y-D-GlCp p-D-FNP-1.2’:2,1’-~-D-sOrp P-D-FNp-1.2’ :2,1‘-a-L-sorp (~-L-Sorf-I,2’: 2,3‘-(~-L-S0rf a-~-Sorf2,1‘:3,2’-a-~-Sorp a-~-Sorp-1,2’: 2,l ‘-a-L-Sorp a-D-SOrp-1.2’ :2.1 ’-a-i-Sorp Cu-L-Sorp- 1.2‘ :2.1 ’-p-L-Sorp a-~-Sorf-l,2’:2,1‘-a-~-Sorp p-L-Sorf-I ,2‘ :2,l ’-a-L-Sorp a-r-Sorf-1.2’ :2, I ‘-p-L-Sorf
-15(20, I.l,CHCl,) +43 (20, 1, CHCI,) -42 (20.2.2, CHCI,) -157 (20.1.1, CHCI,) +29 (20, 1.4, CHCI,) -52.9 (20, 1.4, CHCI,) -119(20,1.6,CHCI,) -0 (20, 1.2. CHC1,) +3.7 (20, 3.3, CHCI,) +3.7 (21, 3.3, CHCl,) - 106.6 (20.0.44, CHCl,) - 19 (20,2.1, CHCI,) -19 (25,2.1,CHC13) -25.3 (20, 1.2, CHCI,)
-
236-238 229-231 -
157- 158 183-184 280-282 172- I73 168-169 171- 172 177-179 155-156
“Formerly assigned as p-O-Fwf-l,2’ :2,1‘-fJ-o-Frufin Ref. 82; assignment corrected, Ref. 83.
Ref. 6 8 8 10 11 11 31 31 82“, 83 12 13 15
23 23 53 72 33 148 148 148 85 85 149 84 84 82 80 80 a4 80 22 80 80 22 80
TABLE IV I3C NMR Spectra of Dihexulose Dianhydridesand Related Compounds Carbon Chemical Shift (ppm) ~
Compound"
C-2
(Y-D-FwP1,2':2.1'-p-~-Fr~p95.3 a-D-FmfI ,2':2,1'-p-~-Fmp 103.1 p-~-Fr~f-1,2' :2,1'-p-~-Frup101.8 P-D-FIuP1,2':2,1'-p-&F~p 97.8 a-~-Fmf1.2' :2.1'-a-~-Fmp 105.4 p-~-Fruf-1,2': 2,1'-a-~-Frup 99.7 : 3,2'-a-D-Frup 102.2 p-D-Fruf-2,l' P-o-Fruf2,l' : 3,2'-p-D-Frup 104.6 a-~-F~f-l,2' : 2.1'-a-D-Fruf 104.8 101.7 p-~-Fmf-1,2' :2.1'-p-~-Fr~f a-D-FN~-1.2' :2,l'-p-~-Fr$ 103.3 :2,3'-p-D-FNf 98.3 P-D-FrUf-I,2' a-~-Fmf-1,2' :2,3'-p-D-FNf 104.6 :6,2'-P-~-Fruf 103.5 p-D-Fruf-2.6' a-D-F*-1,2' :2,6'-P-~-Fmf108.1 p-~-F~f-l ,I' :2,2'-a-D-Glcp 98.5 a-~-Fmf1.1 ' :2,2'-a-D-Gkp 103.3 ,I' :2,2'-a-~-Glcp95.3 p-~-Frup-l
C-2'
C-3
96.4 96.5 97.9
69.9 82.8
97.0 95.7 97.6 96.0
99.7 104.0 102.3 104.9 72.8 73.4
C-4
C-5
C-3'
C-4'
71.5 64.8 69.4 71.4 78.6 84.3 69.4 69.9 80.8 76.0 82.8 72.1 70.4 70.3 73.1 69.8 80.0 77.8 84.1 71.1 71.4 78.0 75.5 82.3 71.7 71.6 79.8 73.2 81.1 71.3,71.5 85.8 77.1 74.1 69.8 69.8 81.0 77.8 84.0 80.2 75.7 82.5 82.7 78.6 84.3 77.8 75.4 77.4 74.5 81.5 73.6 76.3 82.2 76.4 82.9 80.0 73.3 81.2,77.4,72.3 83.4 80.0 75.7 83.1 78.1 77.1 75.4 81.7 74.7 71.5 83.1 78.4 81.8 84.1 75.5 73.8(C-3'),72.9,72.3(C-2',5'), 68.1(C-3) 69.1,69.0, 68.9(C-4',4,5)
C-5'
C-6
69.9 69.9 70.0
60.5 61.5 61.7 64.4 62.1 62.1 62.3 64.3 63.5 65.2 63.3 65.8 65.3 64.3 59.8 64.0 62.0,61.8 63.7 60.8 63.0,62.2 61.6 62.4 64.2 61.2 63.3 64.4 62.3 64.9 62.1 62.2 63.4 64.6 62.0 63.5 62.6 63.4 62.9 62.5 62.6 63.7 62.1 61.6 60.0 64.5 60.7,59.8 61.0 61.9 62.2 58.2 61.3 60.0 69.5 95.1 64.6 62.0 61.7 99.0 64.0 60.1 69.5 94.3
65.6 65.0 66.1 70.1
82.1 85.0
81.2 82.6 72.8 69.9
C-6'
C-1
C-1'
Ref. 88h'
88"'
83d'f
mhc 83d'1f 83d'J 83"f 83d'f 83d'f 83d'J 88"'
9SdeR 95d'X 53h' 72'h 85' 83deJ 85h
(continued)
TABLE IV (continued) Carbon Chemical Shift (ppm) ____
Compound”
C-2
C-2’
108.37 75.44 96.2,95.8 97.8.97.5 104.3 98.2 ~r-L-SOrf-2,l‘ :3,2’-a-L-S0v 104.2,95.2 a-~-Sorp-1,2’ :2,1’-a-~-Sorp 97.5 u-~-Sorp-1,2’ :2,1‘-a-L-Sorp 95.8 p-L-Sorp-l,2’ :2.1’-p-L-Sorp 97.9,97.7 a-~-Sorp-1,2‘ :2,1’-p-~-Sorp96.0.95.9 a-~-Sorf1,2’:2,l’-a-L-Sorp 102.3,96.6 p-~-Sorf1.2‘:2,l’-u-~-Sorp 103.6,96.1 a-~-Sorf-l,2’ : 2,1’-p-~-Sorf103.9,99.3 ‘In D,O. bMeasuredat 50.3 MHz. ‘Referenced to internal acetone (31.1 ppm). dMeasuredat 100 MHz. ‘Assigned by H-C correlation spectmscopy. ’Referenced to internal t-BuOH (30.695 ppm). 8Referenced to external Me$. hMeasuredat 22.5 MHz. ‘Referencedto internal Me,Si. JReferenced to internal 1,Cdioxane (67.4 ppm). %Measured at 125 MHz. ‘See discussion in text
C-3
C-4
i19.92
~
C-5
C-3’
C-4’
~
C-5’
77.78 87.06 75.47 70.98 76.97 69.79 69.84 72.5 74.1 70.1 76.0,74.5,73.1, 70.3,70.1,69.8 83.5(C-3‘) 79.2,78.8,76.4,76.0, 75.1(C-3,4,5,4‘,5‘) 83.5,76.4,74.2,74.0, 72.9,70.1 75.9,74.3,70.1 74.2,72.5,70.1 74.0,72.3(2(3),71.9,69.9,69.0 74.1,72.5,72.4,72.0, 70.0.69.1 80.6,79.0,77.1,74.3, 73.8,70.0 84.0,82.0,77.1,74.2, 72.6.70.1 83.6,81.9,78.9,78.7, 77.0.76.0
69.3
_
C-6
_
_
C-6’
_
_
C-1
_ ____
C-1’
Ref.
64.47 62.98 64.93 93.76 64.3 62.6 62.0,61.6 65.3,64.2, 64.0.63.6 65.2,63.4, 61.5,61.3 65.1,63.2,62.6, 61.4 63.9,63.5 62.6,61.8 62.9,62.5, 62.2,59.6 63.0,62.7,62.3,59.6 66.4,63.1, 63.06,61.0 72.7(2C), 62.1.61.9 63.5,63.1,61.9,61.2
80’
80’
84’“ 90bJ
‘
80’ 80’ 80’ 80’
TABLE V ”C N M R Spectra of Per-0-acetyl Dihexulose Dianhydridesand Related Compounds Carbon Chemical Shift (ppm) Per-0-acetylDerivativeof“
J
C-2
C-2‘
a-D-Fmp-1,2’ : 2.1 ‘-p-~-Fmp92.8 94.7 a-D-FrUf-l,2‘ :2,1’-p-~-Fmp 101.5 95.0 p-~-Fmj-1,2’ :2,l’-p-~-Fmp 101.4 96.6 p-~-Frup-l,2’ :2,l‘-p-~-Fr~p97.1 : 3,2’-P-~-Fmp 103.1,94.5 P-D-Fmf2,l‘ 72.5 p-~-Fmfl,l‘ : 2,2’-a-~-Glcp98.5 p-~-Fnlp-l,I ‘ :2,2’-a-~-Glcp94.1 72.5 p-D-Fmf-2.1‘ : 3,2’-a-D-GlCp 103.73 69.60 93.9,94.5 P-D-FIUP-I,~’ :2,1‘-a-D-SOrp P-D-FI-uP1,2‘:2,l‘-a-L-Sorp 96.8,96.2 97.6 a-~-Sorf-1,2’ :2,3’-a-L-Sorf 102.2 a-~-Sorf-2,1‘ : 3,2‘-a-~-Sorp 102.7,93.6 a-~-Sorp-1,2‘ : 2,l‘-a-L-Sorp 96.0 a-D-Sorp-l,2’:2,1’-a-L-Sorp 93.9 a-~-Sorp-1,2’ :2,1’-p-~-Sorp 93.7,92.4 100.2,96.5 a-~-Sorj1,2’ :2,l‘-a-L-Sorp p-~-Sorj1,2’:2,l’-a-L-Sorp 101.5,94.1 a-L-So$-1.2‘:2,1’-0-L-SOrf 98.5,101.5 ”In cM31,. ’Measured at 50.3 MHz. ‘Measured at 100 MHz. dMeasured at 125 MHz.
C-3
C-4
C-5
C-3’
C-4’
C-5’
C-6
C-6‘
C-1
C-1’
67.2 79.7
69.2 77.9
64.8 81.2
67.1 67.3
68.9 69.0
67.5 67.5
57.8 63.2
61.4 63.2
61.2 61.5
60.9 61.1
70.4,69.0,66.9 80.7,77.9,70.9,68.9, 67.8,67.2 76.5 75.8 78.5 71.5 70.5 68.6 66.7 68.5 67.8 71.1 69.1 68.7 75.73 77.75 81.16 71.18 66.65 71.06 67.2 67.4 68.8 69.82 69.78 69.1 70.2 66.7 68.8 72.6 69.0 77.8,76.6.76.2,74.8,74.6,71.7 78.2,76.6,71.2,70.2,69.8, 69.0 72.5.68.9(2C) 70.0 69.9 69.1 69.6(2C),68.9,69.7, 67.2,66.5 76.4,74.3(2C),72.1,69.5, 69.1 80.6,78.3,75.4,69.7 (2C), 69.0 81.0,78.0,76.2,75.6, 75.1,74.2
65.3,64.3 64.3,64.1,62.2,61.5 63.9 61.6 69.3 93.7 61.7.61.5 69.3 94.0 64.03 64.70 61.33 88.95 61.25 59.2 61.2,61.3 62.2 62.5 62.9 59.7 64.4, 62.8,61.8.60.9 64.8,62.1, 61.9,59.9 59.3
61.1 61.1,60.6,59.2,59.1 63.7.61.5.61.0.59.7 62.5,61.6,61.1,59.2 62.9,62.6, 62.2,61.5
Ref. 88” 88”
88” 31‘ 31 85”
85” 149‘ 84d 84d 82,88” 80
84d 80
80 80 80
248
MERILYN MANLEY-HARRIS AND GEOFFREY N. RICHARDS
IH
TABLE VI NMR Spectra of Dihexulose Dianhydrides and Related Compounds Proton Chemical Shin (ppm) Coupling Constant (Hz)"
H-1, Compound
H-1,
JWb
3.71 12.4 3.78 - 12.5 3.981 12.4 3.99 12.8 3.87 12.4 3.68 12.4 4.I3 12.0 4.18
12.4 3.97 12.4 3.91 12.8
3.86 3.47
H-3
H-5
H-6,
H-6,
J4.5
J5.6
J5m
Jh6b
3.80 4.7 3.51
3.90 3.6 3.72 3.5
4.05 9.0 3.80
4.06
3.88 3.6 4.1
10.0
3.561 3.80 3.76 3.62 3.50
3.82 8.0 4.22 3.6 4.04 7.2 4.31 7.2 3.96
7.2 -3.92 4.05 7.2 4.67 7.6 4.10 1.2 3.91 5.6 3.92
-0
3.65 3.79 3.98
4.04'
3.67'
12' 3.92' 13.5'
3.63'
i
H-4
J,,
1
3.99 12
3.37
H-1,
H-1,
J,,,,
2.0'
3.82 4.2 3.64 2.4 3.94
3.77 3.70 4.8 12.0 3.52' 3.76' - 12Se 1.2' 3.74 3.61 7.2 12.4 3.61h, 3.63h 3.74h,3.77h 3.72 3.60 6.6 12.2 3.87 3.71 5.2 13.6 3.71,3.81
-6 4.05 7.5 4.14
3.98 3.2 3.99 3.2 3.84 3.4 3.91
3.78 6.0 3.73 6.6 3.80
3.70 12.2 3.65 12.4 3.61 12.2 -3.68
3.76
3.97
3.68
-3.53
3.75 3.5 3.54 -9
3.85
3.60e 1.2' 3.34
11.5'
3.82
4.00 2.4 4.14 3.2 3.97 7.6 3.88 8.3 4.02 4.7 3.41 10.4 3.15 9 H-3
H-4
H-5
H-6,
J,,,
J4.5
J5.a
J5lb
~~~
2.0'
3.52 5'
~
5.8
3.7W 3.66 11
-Iff
~~
H-6,
Jam ~
Fructose residue
~ - D - F I uI~.-2':2,I '-a-D-Glcp
4.00 12.4 P-D-Fmf-2,1' :3,2'-a-D-GI~p~.~ -
-
3.55
-
4.00 3.2 4.186 3.5
3.94 6.4 4.353
4.4
4.03 3.0 3.982 4.4
3.80 6.0
3.64 12.0
3.813 6.4
12.1
-
DIHEXULOSE DIANHYDRIDES
249
TABLE VI (continued) Proton Chemical Shift (ppm) Coupling Constant (HzY
H-l'*
H-l'b
J,'x.,'b
3.50
4.17
12.2
H-3'
H-4'
H-5'
H-6',
H-6',
J3,.4
J.V*
J5.,6s
J5',6'b
J6.a.6.b
3.56 10.2
3.89 3.6
4.01 1.5
3.73 I.2
3.84 12.9
Ref. 31,l 13 II3
4.Olf 12.4 3.95 12.4 4.10 12.0 4.08 13.6 3.86 11.6 4.11 12.0
3.70' 3 69
3.73 3.73
3.13 3.51
3.11 5.2 3.W -4.0
3.86 4.2 3.88
3.60
3.84 3.6 3.90 3.0 3.91 3.6 4.08 7.4
10.0 3.71 6.4 3.54 9.6 3.83 8.0
3.99
--3.98 3.95 I.2 3.96 3.99 3.89 3.6
-3.14
3.65 11.2 3.6Ih,3.63h 3.14h,3.11h 3.89 3.61 2.0 12.8 -3.94 3.61 2.4 13.6 3.67 3.75 7.0
83hR 83hN
83h,y 83h,R 83h,R
3.63 12.4
83h,R 83h,P -3.72 3.51 12.2 L
-3.15
3.51 I
12
4.20
4.10
4.20 1.1 3.12 9.2
4.53
3.53 9.2
3.98 -3.57 3.50 10.5'
3.11
3.17
95
3.76
-3.62
95
3.32' 5.3'
3.83' 10.8'
84 84
H-1
H-2
H-3
H-4
H-5
H-6,
H-6,
4.2
J23
J3.4
4.5
J5,h
J5,6b
J6&6b
Glucose residue
5.45 2.8 5.421 3.8
4.19 0.8 -
8. I
4.32 2.8 4.020 8.0
4.32 10.0 3.527 9.2
3.85 3.2
3.82 s.4
3.70 12.2
83"." 149
TABLE VII ‘H NMR Spectra of Per-0-acetyl Dihexulose Dianhydrides Proton Chemical Shift, ppm (Coupling Constant, Hz)”,* Per-0-acetyl Derivative of
VI N
0
H-3 (J3,J H-4 (J4J H-5 (JSb)c H-Sd H-6’(J6,6)p H-3‘ (J3,A’) H-4’ (Jcs) H-5’ (J,,,,.) H-6’ (J5,,6,) H-6’ (J6,.6,)
H-1, H-lh H-1, H-1
CX-D-FI-UP1.2’:2,l‘-p-~-Frqp’ 5.54(10.5) 5.74(3.5) a-D-Fruf-1.2’: 2,1‘-p-~-Fr~p’ 5.43(1.8) 5.21 (5.5) 5.60(10.6) 5.80(3.5) p-D-Fruf-1,2’:2,1f-p-D-Frup’ 5.55(7.5) 5.60(5.1) 5.57(11.0) 5.60(3.1) B-D-FrUp-1,2‘:2,1‘-p-D-F~p’ 5.76(10.9) 5.60 (3.5) ~-D-FIU~-~,~‘:~,~’-P-D-FIU~ 4.04(-0) 4.98(-0)
5.41(9.0) 3.58(4.5) 5.45(1.5) 3.41(1.5) 4.07(3.5) 4.29(4.4) 5.47 3.40 4.06(7.2) 4.29(3.8) 5.34 3.33(1.5) 5.27(1.5)” 3.31(1.5)” 4.24(9.3) 4.47(5.5)
5.40(10.2) 5.26(1.5) a-o-FrufI,2’:2,If-u-D-Frufo 5.28(2.4) 4.95(5.8) a-D-Fruf-I,2’:2,l’-P-~-FrUf 5.20(1.7) 4.95(5.4) 5.15(6.5) 5.36(4.3) p-~-Frup-l,2’:2,1’-a-~-Sorp 5.16(10.3) 5.35(3.4) 4.83(10.0) 5.49(10.0) ~-~-Frup-l,2’:2,1’-a-~-Sorp 5.37(10.5) 5.40(3.0) 5.01(10.3) 5.48(9.6) ~-L-SOI~-I,~’:~,~’-U.-L-SOI~ 4.98(4.3) 5.51 (5.8) 4.23(0.7) 5.24(3.8)
3.92(1.5) 3.88(12) 3.92,3.61 4.40(5.8) 4.16(11.7) 3.90 4.00,3.71t 3.97.3.61 5.31(1.8) 3.81 (1.5) 3.82(12.0) 3.61,3.66 4.95(10.6) 3.51(6.0) 3.91 (11.0) 5.26(1.9) 3.70(1.7) 4.01(13.0) 3.53,4.047 4.95(10.7) 3.65(6.1) 3.85(10.8) 3.54,3.91 4.57(5.5) 4.25(5.5) 4.20(12) 4.12,3.717 4.63(5) 4.2(7) 4.13(11.6) 4.40.4.09 5.35(-1) 4.23 (3.8)
3.92(-11) 3.50(-13) 4.53(- 12) 3.51(-12) 4.43(- 12) 3.41 (-13) 3.31 (-13) 4.24(12.5)
4.00,3.72, 3.64.3.53 3.72,3.72, 3.82,4.10 3.93.3.65, 4.08.3.82 3.49.4.12, 4.33.4.17
Acetates‘ (integration)
Ring Conformations Ref.
1.98(3),2.05(3),2.08(3) ’C, 2.13(6),2.16(3) 2c5 1.58(6), 1.70(6), ’E 1.76(6) ,c* 1.56(3),1.66(6), 4E 1.71(3),1.83(3),1.91(3) ’C, 2.01(6),2.18(12) both 2C, 2.11(3),2.10(6), 2.07(6),1.96(3) 2.14,2.10,2.09 2.14(3),2.11(3) 2.08(12)
27h 27” 27 27” 31
2C, ’E E,
,C, ’C&D) ’CS
82.83 24 84 84
2c,(L) 82
ru-~-Sorf-1,2' : 3,2'-a-~-Sorp 4.06 (-0.6) 4.88 (9.6) ru-L-Sorp-1,2':2,1I-a-L-Sorp 4.95 (10.4) a-D-Sorp-1,2' :2,1'-a-~-Sorp 4.88 (10.0)
5.35 (3.6) 5.50 (9.6) 5.42 (9.9) 5.55 (10.0)
4.73 (5.6) 4.98 (10.8) 4.88 (10.9) 5.05 (10.7)
4.17 (6.8) 3.61 (6.0) 3.58 (6.0) 3.52 (6.1)
4.24 (11.6) 3.95 (10.8) 3.78 (10.0) 3.97 (10.7)
4.05,4.37$ 3.55, 3.79 3.88,3.47 3.67, 3.57$
2.1 1,2.06,2.05(6) 2.01,1.99 2.12,1.96,1.95 2.00,2.04,2.10
p-~-Sorp-1,2':2.1 '-p-L-sorp' 5.53 (10.4) a-~-Sorp-1,2':2,1'-p-~-Sorp 4.84 (9.8) 4.90 (2.1) :2.1 '-cu-L-Sorp 5.32 (6.6) a-~-Sorf-1,2' 4.96 (10.2) P-~-Sorf-1,2':2,1'-a-~-Sorp 5.24 (1.8) 4.84 (9.8) 5.10 (5.7) a-L-So$-12' :2,1'-P-L-SOrf 5.34 (2.0)
5.75 (3.7) 5.51 (9.5) 4.75 (2.8) 5.49 (6.7) 5.47 (10.0) 5.32 (6.0) 5.50 (9.8) 5.60 (5.7) 5.40 (6.9)
5.46 (1.6) 5.39 (8.7) 5.00 (10.7) 4.91 (2.8) 4.52 (5.2) 4.90 (10.9) 4.66 (6.4) 5.00 (10.8) 4.56 (5.0) 4.73 (7.3)
3.42 (1.7) 3.57 (4.5) 3.52 (6.0) P(2.7) 4.18 (4.4) 3.62 (5.5) 4.20 (6.4) 3.51 (6.0) 4.18 (5.8) 4.22 (6.0)
3.52 (-12) 3.90 (-10) "(10.7) 3.82 (12.6) 4.07 (12.0) 3.87 (10.8) 4.20 (-0) 3.91 (10.8) 4.31P (1 1) 4.30P (1 1.2)
4.02, 3.71t 3.65,3.50 3.76, 3.70 3.67, 3.46 3.93, 3.77, 3.74,3.66 3.66,3.94$ 3.46,3.82 4.30,4.23 3.69,3.63
2.O9,2.08,2.06,2.01, 1.99 2.15,2.10,2.07,2.05, 2.00,1.98 2.O9,2.06,2.05,2.01, 1.99,1.96 2.16,2.11,2.09, 2.08(6)
"In CDCI, unless otherwise stated. which was measured at 500 MHz), 500 MHz hMeasured at 100 MHz in Ref. 24,220 MHz in Ref. 27,250 MHz in Ref. 31,400MHz in Ref. 82 (except for cr-~-Sorf-l,2':2,1'-~-~-Sorf, in Refs. 82,84. 1,,- and J5.6.ar,when the ring in question is pyranoid, for Refs. 27,82, 84.JS,&and Js,6.a for other refs. ' H - k and H-6'ax in refs. 80.84 when the ring in question is pyranoid, otherwise H-6a and H-6'a. eJ5,6rr.when the ring in question is pyranoid, for Refs. 27,80.84.J5,66 for other refs. 'H-6eq and H-6'eq in refs. 80,84,when the ring in question i s pyranoid, otherwise H-6b and H-6'b. RGeminal coupling constants are assumed to be negative even if not so stated. htindicates that H-I and H- 1 ' are distinguished, $indicatesthat axial and equatorial positions are distinguished. '2.14Z 0.04 ppm for an axial acetate group, 2.04 -C 0.05 ppm for an equatorial acetate group in CDCIP. 'In C6D6except for the acetate resonances which are measured in CDCI,. 'See discussion in text.
'In C6D,. "Compare with results of X-ray crystallographydiscussion in text. TJ,,,,, + J5+J = 3.0k2'. "Formerly assigned as P-u-Frqf-l,2' : 2,l'-P-o-Frufin Ref. 82; assignment corrected, ref. 83. PSome ambiguities in assignments, see ref. 80.
TABLEVIII ‘H NMR Spectra of Per-0-acetyl Fructose Glucose Dianhydrides Proton Chemical Shifl (ppm) Coupling Constant (Hz)” Fructose Residue
Per-U-acetylDerivative of
!N 2
H-1, J,,,,
H-1,
Glucose Residue
H-3
H-4
H-5
H-6,
H-6,
H-1
H-2
H-3
H-4
H-5
H-6,
H-6,
J3,4
J4J
J5,6a
J5,6b
J6a,6b
Jl,Z
J2,3
J3,4
J4J
J5,6a
J5,6b
J6a.b%
3,6p-o-Fruf-l,2’ : 2,l’-a-~-Gl~p3.96 3.40 4.83 2.2 3‘,6’ 12.3 p-~-Fr~f-1,2‘:2,1’-a-D-Gl~p-3’,6’ 4.19 3.42 5.54 11.7 3.6 p-~-Fruf-l,2’ :2.1’ - a - ~ - G l c p 4.25 3.46 5.23 12.2 6.0 f3-WF1~f-l, I ’ :2,2’-a-D-Glcp 4.24 3.96 4.72 12Sd 5.0 p-0-Fry- 1, I :2,2’-a-D-Glcp 4.24 3.83 5.63 12.5 10.6 p-D-F1~f-2,1’ :3,2‘-a-D-Gkp 4.299 4.160 4.079 11.9 1.1
5.15 0.5
5.34 3.3 5.70 6.5 5.26 5.0
5.84 3.4 5.050
2.0
4.53 -0
4.10 5.5
5.71‘ 1.3 5.71
1.3 4.193 7.7
5.43 3.80 2.4 5.2 3.65 4.52 4.39 5.21 11.0 3.0 4.0 7.0 5.62 3.64 3.5 10.0 4.08 3.95 4.73 3.97 3.5 9.5 11.1 2.0 4.10 4.17 3.97 5.00 3.5 9.5 2.0 13.3 4.459 4.362 5.294 3.823 3.1 5.2 11.5 5.5
4.08 -0
4.08
4.68
4.68 4.58 4.20 3.0 0 4.38 3.87 3.55 3.0 2.5 0 5.25
4.46 5.0 5.96 9.5 10.0 5.76 4.69 9.5 9.5 6.28 5.31 9.5 9.2 5.270 4.886 5.1 6.9
3.96 148’ 10.6 3.24 148‘ 11.0
148l 4.05
1.6 4.38 4.53 4.0 2.0 4.329 4.338 7.1 3.0
Ref.
858
I lSd
4.21 U h 12.3 4.177 14F‘ 11.4
‘Geminal coupling constants are assumed to be negative even if not so stated.’47 bMeasured at 250 MHz in CDCI,. ‘Measured at 250 M H z in C6D,. dSome ambiguities exist in the text resulting in the following duplicate assignments for three of the atoms: H-l’a 4.06 ppm, Jl,a,,,b 12.4 Hz; H-5’ 4.14 ppm, JS.,b.a 6.6 Hz.JS.,., 6.6 Hz; H-6b 4.21 ppm. ‘A multiple1 at 4.26-4.20 ppm (2H) is assigned as H-5 and H-6a. Measured at 220 MHz in C6D,. SMeasuredat 400 M H z in CDCI,. hMeasured at 200 M H z in C,D,. ‘Assigned by correlation spectroscopy.
TABLE IX Partial Mass Spectra of Per-0-trimethylsilylatedDihexulose Dianhydrides" Compound"
*
Rglueitol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
1.710
1.737
1.806
1.862
1.883
1.883
1.905
1.914
1.930
1.953
1.973
1.987
2.022
2.075
100.0 10.7 24.1 58.7 74.6 3.9 8.7 0.6 23.4 0.5 0.3 1.5 0.4 0.2 -
67.0 9.6 13.7 0.8 100.0 4.2 6.8 0.3 21.4 0.5 0.3 0.8 0.3
100.0 12.2 20.4 39.5 85.0 4.1 5.4 0.5 29.4 0.5 0.2 0.8 0.2 0.1 0.1
46.4 7.5 9.4 0.8 100.0 2.2 2.6 0.2 12.9 0.4 0.2 0.4
89.7 9.2 24.9 55.9 100.0 2.4 4.1 0.3 20.1 0.3
60.8 5.6 19.3 100.0 26.0 3.4 4.1 6.3 0.6 0.6
% abundance
mlz
N
VI W
73 103 147 204 217 36 1 362 47 1 509 561 563 65 1 653 74 1 756
100.0 21.5 14.6 0.8 80.5 9.4 3.3 0.3 9.3 0.9 0.6 0.6 11.2 0.1 -
100.0 15.7 20.8 90.5 22.9 13.2 4.8 0.4 7.9 0.9 0.6 0.4 25.1
100.0 17.7 25.4 33.8 19.6 12.2 4.7 0.4 1.2 0.5 -
0.7 32.2
-
-
-
-
100.0 22.5 17.3 1.4 32.8 27.6 9.7 1.5 0.7 7.7 0.6 52.1
-
83.0 6.0 23.7 100.0 23.2 2.1
4.2 0.4 16.4 0.4 -
0.5 0.2 0.3
100.0 10.2 20.4 34.6 60.9 2.0 2.8 0.5 20.5 0.5 0.2 2.7 0.8
-
0.1
100.0 14.6 15.1 1.1 91.4 4.4 2.7 0.5 29.2 1.o 0.5 2.1 0.8 0.1 -
100.0 15.4 21.5 5.3 83.9 11.6 7.6 0.4 2.2 1.2 3.5 1.1 0.4 0.4 -
-
0.6
-
-
-
-
-
-
"Key: 1 = a-o-Fruf-1,2':2,3'-p-o-Fmf; 2 = p-o-Fmf-2,l':3,2'-u-o-Fmp; 3 = p-o-Fmf-2,1':3.2'-p-o-Fmp; 4 = p-~-Fr~f1,2':2,3'-p-~-Fruf; 5 = a-~-Frup-1,2':2,I'-p-o-Fmp; 6 = 8-~-F~~1,2':2,1'-u-~-Fmp; 7 = u-o-Fmf-1,2':2,1'-a-o-Fmf; 8 = a-D-Fruf-l,1':2,2'-a-~-Gl~p; 9 = a-o-Frufl,2':2,1'-p-~-Frup; 10 = a-~-Fmf1,2':2,1'.p-~.~mf; 11 = a-D-Fmf-1.2':Z,l'-a-o-Frup;12 = p-~-Fruf-l,2':2,l'-p-~-Fr~f; 13 = p-~-F1~f-l,2':2,1 '-p-~-Fmp; 14 = unidentified in Ref. 83, subsequently shown to be p - ~ - F m p 1 ,2':2,1'-P-o-Frup(MM-H) 'Chromatography: Hewlett-Packard Ultra2 (25 m X 0.33 mm) cross-linked phenyl methyl silicone fused silica capillary column.Temperature program 55' (1 min.) + 30"C/min. to 180°C. and 4'C/min. to 320°C.
TABLE X Glycosyl Di-D-fructose Dianhydrides
u N l P
5-O-a-D-GlUCOpyr~OSyl-a-D-fruCtOpyranOSe 5-O-a-D-glucopyranosy~-~-D-fructopyranose l,2‘ :2,1 ’-dianhydride (22) 4-O-a-D-Glucopyranosyl-a-~-fructopyranose 4-O-a-D-glUCOpyranOSyl-P-o-fructopyr~OSe 1,2’ :2,l ’-dianhydride (23) 4-O-a-D-~a~actopyranosy~-a-D-fructopyranose 4-O-a-~-galactopyranosy~-~-~-fructopyranose 1,2‘ :2.1 ’-dianhydride (24) 6-O-a-D-~~ucopyranosy~-a-D-fructofuranose P-D-fructopyranose 1,2’ :2,1 ‘-dianhydride (25) 6-O-a-D-Glucopyranosy~-a-~-fructofufanose 5-O-a-~-glucopyranosyI-~-~-fructopyranose 1.2’ :2,l ’-dianhydride (26) 6-O-a-D-~~ucopyranosy~-a-~-fructofuranose 4-O-cY-D-glUCOpyranOSyl-P-D-fNCtOpyranOSe 1.2 ’ :2,1 ’-dianhydride (27) 4-O-a-D-GlUCOpyranOSyl-a-D-fructofuranOSe 4-O-a-D-glucopyranosyl-~-D-fructopyranose 1.2’ .2,1 ‘-dianhydride (28) 4-O-cY-D-GluCOpyr~OSyl-cY-D-fruCtOf~~OSe P-D-fructopyranose I ,2’ :2.1 ’-dianhydride (29)
Ct-D-fIUCtOfuranOSe 4-O-a-~-glucopyranosyl-~-~-fructopyranose 1.2‘ :2,1 ’-dianhydride (30) 4-O-a-D-~a~actopyranosyl-cu-o-fructofuranose 4-O-a-D-galactopyranosyl- P-D-fructopyranose 1,2‘ :2,1 ’-dianhydride (31) 3-O-cY-D-GlUCOpyranOSyl-a-D-f~CtOfu~~OSe 3-O-a-D-glUCOpyranOSyl-P-o-fructopyCanOSe 1,2’:2.1 ’-dianhydride (32) ~-~-a-D-~~ucopyranosy~-~-D-fructofuranose P-D-fruCtOpyCanOSe 1,2’ :2.1 ’-dianhydride (33) 5,5’-Di-0-a-D-glucopyranosyl-di-P-D-fructopyranose 1.2’ :2,l ‘-dianhydride (34) ~-O-a-D-~~ucopyranosy~-di-~-D-fructopyranose 1.2’ :2,1 ’-&anhydride (35) 6,6’-Di-O-a-D-glucopyranosyl-di-~-~-fructofuranose 1.2‘ :2,1 ’-dianhydride (36) 3,3’-Di-O-a-D-g~ucopyranosyl-di-~-D-fructofuranose 1,2’ :2,1 ’-&anhydride (37) 6-O-~-D-Glucofuranosy~-a-D-fructofuranose p-D-frUCtOfuranOSe 1,2’ :2,1 ’-&anhydride (38) a-D-Fructofuranose 6’-O-a-D-g~ucopyranosyl-~-D-fructofuranose 1.2’ :2,l ‘-dianhydride (39) a-D-Fructofuranose 6’-O-~-~-fructopyranosy~-~-D-fructofuranose 1,2’ :2,l ’-dianhydride (40) 6-O-a-D-Glucopyranosyl-a-~-fructof~1ranose 6-O-a-~-glucopyranosyl-~-D-fructofuranose 1,2’ :2,l ‘-dianhydride (41) 4-O-~-D-GlUCOpyranOSyl-a-D-fruCtOf~~OSe 4-O-u-D-glUCOpyranOSyl-~-D-fructofuranose 1,2’ :2.1 ‘-dianhydride (42) ~-~-a-D-~~ucopyranosy~-~-~-fructofuranose 3-O-a-~-glucopyranosyl-~-D-fructofuranose 1,2’ :2.1 ‘-dianhydride (43) 4-~-a-D-~~actopyranosyl-a-D-fructofuranose 4-O-a-~-galactopyranosyl-~-~-fructofuranose 1,2’:2,l ’-dianhydride (44) 6,6’-Di-O-a-~-glucopyranosyl-di-~-~-fructofuranose 1.2‘ :2.3’-dianhydride (45) 4,4’ -Di-0-a-D-glucopyranosyl-di-P-o-fructofuranose1,2’ :2,3 ‘-&anhydride (46) 6-O-a-D-G~ucopyranosy~-a-~-fructofuranose 6-O-a-D-g~ucopyranosy~-~-D-fructofuranose 1,2’ :2,3 ‘-dianhydride (47) 6,6’-Di-O-a-~-glucopyranosyl-di-a-~-fructofuranose 1.2’ :2.1 ‘-dianhydride (48) With the exception of compounds 26.27.29. and 30.which are reported in Ref. 86, and compounds 3-40,which are reported in Ref. 83, compounds 22 through 48 are from Ref. 88. Compounds 41 and 46 are also reported in Ref. 87. as it compound 48.
?
DIHEXULOSE DIANHYDRIDES
255
TABLE XI Optical Rotations and Melting Points of Glycosyl Di-o-fructoseDianhydrides and Their Per-0-acetyl Derivatives Compound" 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 40 41 42 43 44 45 46 47
[a]? (degrees)
+18 (c 1, H,O) +47 (c 0.8, H,O) -32 (C I , H,O) +36 (c 0.5, H,O) +45 (c 0.8, H,O) +91 (c 0.8, H,O) +89 (c 0.8, H,O) +61 (c 1, H,O) +48 (c 0.8, H,O) - 14 (C 1, H,O) +61 (c 0.9, H,O) +51 (c 0.8, H,O) - 14 (C 1 , H,O) -32 (C 1, H20) + 143 (c 0.6, H,O) +118(c I.l,H,O) - 10.0 (25,30, H,O) + 109 (c 0.5, H,O) + I15 (c 0.7, H,O) + 117 (c 1, H20) +18(c1,H2O) + 148 (c 0.6, H,O) +68 (c 1, H,O) + 133 (c 0.5, H,O)
degrees of per-acetate
[ ( Y ] ~ ~
+72 (c 1, CHCl,) +70 (c 1, CHCl,) -70 (C 1, CHCI,) +60 (c 1.2, CHCI,) + 5 5 (c 1, CHCI,) +76 (c 1, CHCl,) +74 ( c 1, CHCl,) +40 (c 1.2, CHCI,) 0 (c 1.0, CHC1,) -28 (C 1, CHCI,) +76 (c 0.9, CHCl,) +36 (c 0.9, CHCl,) +8 (c 0.5, CHCI,) -20 (C 1, CHCI,) +118(cOS,CHCI,) + 124 (c 1, CHCl,) +96 (c 0.5, CHCI,) +lo2 (c 1.1, CHC1,) +95 (c 1, CHCI,) -8 (c I,CHCl,) +85 (c 0.5, CHCI,) +68 (c 1, CHCI,) + 112 (c 1.1, CHCI,)
Melting point of per-acetate("C) 136- 139 (EtOH) -
-
119-121 (EtOH) -
137-141 (EtOH) -
-
187-188 (EtOH) 163-165 (EtOH) -
-
'With the exception of compounds 26,27,29 and 30, which are reported in Ref. 86, and compound 40, which is reported in Ref. 83 compounds 22 through 47 are reported in Ref. 88.
TABLEXI1 I3C NMR Spectra of Dianhydride Components of the Glycosyl Di-D-fructose Dianhydrides Carbon Chemical Shift (ppm)
v1 w
Q\
Compound"
c-2
c-2'
c-3
c-4
c-5
c-3'
c-4'
C-5'
C-6
C-6'
c-1
c-1'
22
95.2 95.6 95.6 103.3 103.5 103.4 103.3 103.4 103.1 103.3 103.5 103.2 97.9 97.9
96.3 96.5 96.3 96.6 96.6 96.7
70.0 69.9 71.3 82.7 82.7 82.7 82.6 82.8 82.8 82.9 86.1 86.2 70.7 70.7
71.5 77.8 80.0 78.8 78.8 78.8 84.0 84.1 78.7 87.5 75.9 76.0 73.5 73.5
72.3 65.2 64.7 83.3 83.3 83.2 81.1 81.3 84.4 81.8 85.5 85.1 79.5 79.7
69.7 68.8 67.6 69.5 69.8 68.9 68.7 69.4 68.9 67.5 80.0 69.5
70.0 77.2 77.6 69.9 70.1 77.8 77.6 69.9 77.9 77.5 69.7 70.0
79.9 69.5 67.9 69.9 78.8 69.8 69.7 69.9 69.8 68.0 70.3 70.0
61.5 61.7 61.8 62.0 62.5 62.3 61.8 62.4 62.1 61.8 62.3 62.0
73.2
69.9
61.9 62.0 61.9 62.4 62.0 61.5 62.1 61.7 62.3 62.4 62.7 62.4 64.1 64.1
63.2 64.5 63.9 64.4 63.2 64.4 64.3 64.4 64.4 64.0 64.7 64.5
70.4
59.6 60.7 60.5 67.7 67.6 67.6 61.8 62.0 62.1 61.8 61.7 61.9 64.4 64.4
23
24 25 26 21 28 29 30 31 32 33 34 35
96.6
96.5 96.7 96.5 96.2 96.6 97.9
65.3
64.3
36 37 38
39 40 41 42 43 44 45 46 47
48
104.9 105.4 103.9 103.4 103.4 103.5 105.5 103.6 103.4 103.4 104.7 104.5 111.6 104.9 106.9
99.9 100.2 100.1 100.8 102.0 100.0 99.7 100.5 98.9 98.9 106.2 102.6
80.5 86.6 82.5 83.0 83.0 82.6 82.3 82.8 85.9 82.9 17.7 77.7 83.5 81.6 82.5
78.1 76.1 79.0 78.7 78.7 78.6 79.7 84.1 75.8 87.5 75.3 82.2 78.8 77.2 80.0
82.9 83.1 83.8 84.4 84.4 83.1 85.1 81.4 85.3 81.8 80.1 81.2 84.6 79.8 84.9
78.0 77.8 77.8 17.6 80.6 77.7 83.5 77.3 83.4 83.7 78.3 82.3
75.6 76.0 15.4 75.1 77.8 82.3 75.1 85.0 77.0 81.4 77.5 73.5
82.3 80.6 80.9 80.3 84.1 81.2 82.2 81.6 74.1 71.4 81.7 79.1
67.7 61.8 68.6 63.6 63.1' 67.6 69.7 62.0 61.7 61.8 69.6 63.6 69.9 67.6 12.1
63.7 10.4 63.7 70.1 69.7 63.9 63.4 63.8 69.3 62.8 71.6 67.6
61.8 62.3 62.1 62.2 62.6' 62.7 63.4 62.4 62.5 62.4 63.0 62.0 63.6
64.I
63.6 63.1 63.2 63.3 65.4 63.1 63.3 63.2 64.3 63.8 -
59.7
64.7
With the exception of compounds 26.27.29 and 30, which are taken from Ref. 86, and compounds 38 through 40, which are reported in Ref. 83; compounds 22 through 48 are from Ref. 88: Alternative assignments for compounds 41 and 46 and assignments of compound 48 are from Ref. 87. bFor compounds from refs. 86 and 88 measured at 50 MHz in D,O referenced to internal acetone 31.1 ppm. For compounds from Ref. 87, no experimental details are available, but are presumed to be referenced to external (CH,),Si. Compounds from Ref. 83 are measured at 100 MHz in D,O and referenced to internal t-BuOH (30.695 ppm.). 'These two assignments can be interchanged.
TABLE XIlI 13CNMR Spectra of the Fructose Components of Per-0-acetyl Glycosyl Di-D-fructose Dianhydrides
Carbon Chemical Shift (ppm)b
m E
Compound"
c-2
c-2'
c-3
c-4
c-5
c-3'
c-4'
c-5'
C-6
C-6'
C-1
c-1'
22 23 24 25 26 27 28 29 30 31
94.6 92.5 92.5 101.5 102.1 101.3 101.3 101.4 101.3 101.3 102.5 102.1 96.9 96.9 102.7 105.3 101.5 101.3 102.5 101.6 102.6 102.8 102.6
92.5 94.6 94.8 94.9 95.0 94.9 95.0 94.9 94.9 94.8 94.7 95.0
68.6 69.7 70.4 80.7 80.6 80.5 79.7 79.7 79.4 79.4 85.3 85.0 68.6 68.6 79.5 83.1 80.6 79.4 85.2 79.4 76.3 76.6 79.3
69.3 71.7 73.4 78.0 77.9 77.7 83.8 83.8 77.6 85.3 77.4 77.6 70.3 70.3 77.6 78.0 78.0 83.8 77.9 85.5 76.3 80.5 78.0
69.9 65.8 66.2 81.4 81.4 81.1 81.8 81.9 80.9 81.2 79.2 79.4 73.2 73.2 79.7 79.5 81.2 82.0 80.2 81.4 78.5 79.0 79.9
67.1 69.0 68.7 67.4 67.2 69.0 69.0 67.2 69.0 68.7 73.8 67.2
69.0 70.2 73.2 68.9 69.6 70.3 70.0 68.9 70.3 73.1 68.7 68.9
73.4 69.9 67.7 67.8 73.8 69.8 69.9 67.4 69.8 67.5 68.4 67.5
62.4 61.5 61.8 61.5 62.4 61.2 61.3 61.4 61.2 61.2 62.2 61.8
70.3
66.8
76.1 76.9 84.8 76.3 80.3 80.1 79.1
75.8 79.4 77.5 82.4 77.9 79.7 76.5
78.2 77.5 78.9 78.5 71.8 70.6 75.3
61.2 61.3 61.3 61.5 61.5 61.2 61.0 61.2 61.3 61.1 61.8 61.6 63.2 63.3 61.1 59.4 61.5 61.4 61.8 61.4 62.3 62.0 64.2
60.7 60.3 60.5 61.1 61.0 60.8 60.9 60.8 60.8 60.6 60.9 61.6
68.9
58.9 56.6 56.6 67.3 67.4 67.3 63.0 63.0 63.0 62.8 62.8 63.5 62.9 62.9 66.9 63.5 67.5 62.7 63.0 62.8 69.5 64.0 67.1
32
33 34 35 36 37 41 42 43 44 45 46 47
97.0
99.5 99.2 98.6 99.9 99.1 98.6 101.5
62.2
69.5 64.4 64.3 64.2 67.6 64.0 68.9
"With the exception of compounds 26.27.29, and 30,which are taken from Ref. 86, compounds 22 through 37,and 41 through 47 are from Ref. 88. bMeasured at 50 MHz in CDCl,, referenced to central peak of CDCI, triplet at 76.9 ppm.
63.0
62.6 62.3 62.9 62.5 63.9 63.9 59.4
TABLE XIV 'H NMR Spectra of Glycosyl Di-o-fructose Dianhydride=
Proton Chemical Shift (ppm)" Coupling Constant (Hz) H-1,
H-1,
J,a,lb
H-3
H-4
H-5
H-6,
J34
545
J5.6a
J5,6b
H-6, J6a,6b
Compound
H-lfa
H-l',
Jl'a,l'b
H-3'
H-4'
H-6',
H-6',
J3.p.
'4.5.
J5',6'a
H-5'
J5',6'b
J6a,6'b
H-6,'
H-1
H-2
H-3
H-4
H-5
H-6,
JL2
JU
J3.4
J4.5
J5,6a
J5,6b
~
38
39
40
4.19d 12.4
4.14d 12.4
4.11d 12.4
3.65d
3.67d
3.68d
3.98d 2.0
3.99d 2.8
3.99d 2.8
3.95dd 6.0
3.91 dd 6.0
3.91dd 6.0
4.11m 2.8
3.97111 2.0
3.93dd 6.0
3.74dd
3.97m -3.84
"Measured at 400 h4Hz in D,O; referenced to internal 1-BuOH (1.203 ppm.) *Assignments for glucosyl residues. 'Assignments for fructopyranosyl residue.
3.66dd 12.8
-3.68 12.0
-3.70
4.10d 12.4 5.02 s
3.54 dd 9.8
3.83 d 8.4 4.21 bd 5.6 3.85 d 8.0 -3.72 9.6
4.06 d -0 4.16 dd 1.2 4.08 dd 2.8 3.40 dd 9.2
H-1,
H-1,
H-3
H-4
4.12d 12.0 3.79
3.58d
3.84d 8.0 3.88
4.41dd 7.8 3.88
4.13 d 12.0 4.94 d 3.6
3.57 d 4.19 d 0.8 3.58 d
J6r.6h
~
3.88 dd -3.97 m 3.2 -4.04 m
~~
3.74 dd 3.6 3.84 dd -3.6
-3.68
H-5
3.65 dd 12.4 3.66 dd 12.4
3.7 -3.88
H-6,
H-6,'
3.99m
-3.84
-3.70
3.99
-3.70
-3.80
TABLE XV Derivatives of Di-D-fructose Dianhgdrides ~
Compound
Ref.
6-Deoxy-6-iodo-a-~-fructofuranose P-D-fructopyranose1.2':2.1 '-dianhydride(49) 6-Chloro-6-deoxy-a-~-fructofuranose P-o-fructopyranose1,2' :2.1 '-dianhydride(50) 6-S-Heptyl-6-thio-a-~-frucrofuranoseP-o-fructopyranose1.2' :2, I '-dianhydride(51) 6-Azido-6-deoxy-a-o-fructofuranose P-D-fructopyranose1,2':2,1'-dianhydride(52) 6-Amino-6-deoxy-a-o-fructofuranose P-D-fructopyranose1.2' :2,i '-dianhydride(53) 6-Acetamido-6-deoxy-a-~-hctofuranose P-D-fructopyranose1,2':2,1 '-dianhydride(54) 3,6-Anhydro-a-D-fructofuranose P-o-fructopyranose1,2' :2.1 '-dianhydride (55) 6-Deoxy-6-isothiocyanato-~-~-fmctofuranose P-D-fruCtOpyranoSe1,2':2,1'-dianhydride(56) 6-Deoxy-6-iodo-a-~-fructofuranose 6-deoxy-6-iodo-~-~-fructofuranose 1.2':2,1'-dianhydride(57) 6-Chloro-6-deoxy-a-~-fructofuranose 6-chloro-6-deoxy-~-~-fructofuranose 1,2':2,1'-dianhydride(58) 6-S-Heptyl-6-thio-a-~-fructofuranost. 6-S-heptyl-6-thio-~-o-fructofuranose 1,2':2,l'-dianhydride(59) 6-Azido-6-deoxy-a-~-fructofuranose 6-azido-6-deoxy-P-o-fructofuranose 1,2':2,1'-dianhydride(60) 6-Amino-6-deoxy-a-~-fructofuranose 6-amino-6-deoxy-P-D-fructofuranose 1.2' :2,l'-dianhydnde(61) 6-Acetamido-6-deoxy-~-~-fructofuranose 6-acetamido-6-deoxy-~-~-fructofuranose 1,2' :2,I '-dianhydride(62) 3,6-Anhydro-a-o-fructofuranose 6-deoxy-6-iodo-P-o-fructofuranose 1.2' :2, I '-dianhydride(63) 3,6-Anhydro-a-~-fructofuranose 3,6-anhydro-P-~-fructofuranose 1,2':2,l'-dianhydnde (64) 6-Azido-6-deoxy-a-~-fructofuranose 6-deoxy-P-o-rhreo-hex-5-enofuranose 1.2' :2,l'-dianhydride"(65) 6-S-Heptyl-6-thio-a-~-fructofuranose 6-deoxy-P-o-rhreo-hex-5-enofuranose1.2' :2, I '-dianhydride"(66) 4,5:4',5'-Di-O-isopropylidene-di-~-o-fruct~pyr~ose 1,2':2,1'-dianhydride (67) 6,6'-Dideoxy-6,6'-diiodo-di-P-~-fructofuranose 1.2':2,1'-dianhydride(68) 6-Deoxy-6-iodo-P-~-fructofuranose 6-deoxy-6-iodo-P-o-fructofuranose 1,2' :2,3'-dianhydride" (69) 6-Chloro-6-deoxy-~-~-fructofuranose 6-chloro-6-deoxy-~-~-fructofuranose 1,2' : 2,3'-dianhydride" (70)
119 119
~~
"Only as the per-0-acetyl derivative.
119 119 119 119 147 150 119 I19 119 119 119 I19
147 147 119 I19 151 119 119 119
P
9
TABLE XVI Optical Rotations and Melting Points of Di-D-fructose Dianhydride Derivatives and Their Per-0-acetates Compound 49 50 51 52 53 54 55 56 51 58 59
60 61 62 63
64
[a]? (degrees)
-34 (c I , H,O) -43 (c 1.2, H,O) -33 (c 1, MeOH) -28 (c 1, H,O) -41 (c 1, H,O) -33.5 (c I , H,O) -50 (c 1.1, H,O) - 16.0 (c 1. MeOH) +34 (c 1, EtOH) +21 (c 1, H,O) +21 (c 0.8, EtOH) +52 (c 0.75, acetone) +29 (c 1, H,O) +28 (c 0.9, EtOH) +29 (c 1.2, acetone) +77 (c 1, H,O)
Melting Point "C 163- 164 (dec., EtOH) 181-182(dec.,MeOH) 201 -203 (H,O)
-
-29.5 ( C 1.4, CHCI,) -53 (c 1.2, CHCI,) -31 (c 1.2, CHCI,) - 30 (C 1, CHCI, )
-
-
-
-
-
144- 145 (EtOAc) -
-
-
-
+5
189-191 (EtOH)
-
155-156 (dec.)
-
204 -205 (EtOH)
66 -297.7 (c 0.8. MeOH) +88 (c 0.7, MeOH)
Melting point of per-acetate
-52 (C I , CHCI,) - I8 (c 1.3, CHCI,) -34 (c 1, CHCI,) 0 (c I , CHCI,) -8 (c 1, CHCI,) +2 (c 1.1. CHCI,) +32 (c 1, CHCI,)
65 61 68
[a]? (degrees) of per-acetate
182-184 146-147 (dec.)
69 70
164- 165 (CHC1,-hexane)
191- I92 (EtOH) 197- 198 (EtOH) 86-87 (EtOH) 124- 125 (EtOH)
(c 0.8, CHCI,) +24 (C I , CHCI,)
-
+40 (c 1, CHCI,) + I 5 (c 1, CHCI,) + 1 (c 0.65, CHCI,) -310.9 (c 1 CHCI,)
152-153 (EtOH) 116- 117 (EtOH) 95 - 96 (EtOH) 238-239 (EtOH)
-
-
- 17 (c 0.6, CHCI,) - 10 (c
0.6, CHCI,)
-
Ref. 1I9
119 1I9 1 I9 119 119 147 150 119 119 119 119 119 119 147 147 119 1 I9
@
5 g
n
J:
-e 0
E
8
151
119 I19 119
"A viscous, enantiotropic liquid crystal having cp 52.4"(AH 1.7kJ mol.-'). w
Q'
TABLE X W I3C NMR Spectra of the Fructose Components in Di-D-fructose Dianhydride Derivatives Carbon Chemical Shift (ppm)
h) h) m
Compound
C-2
c-2'
4!Fb 50"" 51' 52' 53' 54' 55' 56e.f
102.9 103.2 103.2 103.1 103.1 103.6 101.8 103.2 103.2 103.6 103.0 103.3 103.3 103.4 102.0 104.6 95.5 105.6
96.3 82.4 96.4 82.8 97.1 83.7 82.5 96.3 96.5 82.6 96.5 82.4 96.6 77.8 96.7 81.2 100.1 82.9 100.1 82.3 100.0 83.8 100.1 82.6 99.8 82.6 99.9 82.9 99.8 77.7 103.6 77.2 76.0,72.8 (2C) 82.3
579 58' 59
6V 61' 62h 63b 64' 6IhJ 689
c-3
c-4
c-5
c-3'
C-4'
c-5'
C-6
82.0 79.6 82.8 79.4 80.0 80.1 75.4 79.9 82.8 79.8 82.5 80.6 80.0 80.0 75.4 75.4
83.1 83.1 84.5 82.7 84.7 80.3 81.5 84.0 84.5 83.5 84.5 84.2 85.0 80.3 81.4 81.8
69.3 69.4 70.7d 69.3 69.4 69.3 69.3 70.1 80.4d 78.0 80.2d 79.6 78.0 77.8 78.1 78.8
69.7 69.8 70.9 69.7 69.8 69.8 69.7 70.8 80.2d 76.8 80.0" 77.4 76.5 76.6 79.0 76.3
69.7 69.8 71.od 69.7 69.8 69.8 69.8 70.8 82.1 81.4 82.3 81.1 82.6 82.6 81.0 81.4
6.4 44.7 35.3 51.0 42.9 42.1 71.5 47.1 7.6 44.8 35.1 52.6 43.0 41.6 71.4 71.5
81.9.81.8
7.9
C-6'
c-1
C-1'
Ref.
62.3 62.0 61.9 62.4 63.1 63.1 61.9 62.3 62.1 62.3 62.0 62.5 62.7 63.9 62.8 62.8 9.5 63.7d 62.7 46.2 37.2 63.5d 63Sd 54.6 62.7 44.8 42.9 62.7 64.7 8.5 72.1 65.9 63.7,61.4 (C-1.6) 61.3
64.2 64.3 64.7 64.2 64.3 64.4 64.5 63.5 63.8d 63.5 63.8d 63.8d 63.4 63.4 63.6 64.2
119 119 119 119 119 119 147 150 119 119 119 119 119 119 147 147 151 119
"A personal communicationfrom the authors indicates that the assignments for these two compounds were inadvertently inverted in the original paper. Measured at 50.3 M H z in D,O (internal acetone at 3 1.1 ppm). 'Measured at 50.3 MHz in methanol-d, referenced to central peak at 49.0 ppm. %ese pairs of assignments may need to be reversed. 'Measured at 75.5 M H z in methanol-d,. 'Additional signal at S 133.2 (NCS). gMeasured at 50.3 MHz in acetone-d, (central peak at 29.8 ppm). hMeasuredat 50.3 MHz in chloroform-d (internal Me,Si). 'CMe,, dioxolane at 6 109.3;8 27.4 and 25.5 (2 Me).
TABLE XVIII "C NMR Spectra of the Fructose Components in Per-0-acetylated Di-o-fructose Dianhydride Derivatives Carbon Chemical Shift (ppm) Compound
C-2
c-2'
c-3
4!P
100.8 101.2 100.9 101.4 101.2 100.3 101.7 101.2 101.3 101.0 101.5 101.5 100.7 103.0 101.8 101.1 95.9 103.6 103.2
94.7 94.6 94.7 94.7 94.9 94.8 94.6 99.7 99.4 99.6 99.4 99.7 100.0 101.2 98.9 99.9
80.9 81.1' 81.0 81.0 80.7 75.9 80.6 81.0 81.1' 81.4 81.0 80.4 76.3 76.6 81.0 81.5
5Wb
h)
E
51h 52h 54" 5Sd 56',f 57b 58" 53 6ob 62" 63d 64d 65b 66" 67'.8 63 7oh
99.1 99.2
C-4
80.5 78.6 80.2 78.3 78.7 75.3 78.7 80.6 78.9 79.9 78.1 78.8 75.5 75.8 78.5 81.5 73.9 (2C). 13.5 76.9 78.6 77.2 76.2
C-5
C-3'
C-4'
C-5'
C-6
81.7 81.2' 81.5 81.5 81.1 77.7 80.9 81.8 81.2' 81.5 81.6 81.3 77.9 77.5 81.9 80.0
66.9 66.9 67.0 67.0 67.2 67.1 66.9 76.5 76.9 76.2 76.3 77.4 76.6 78.0 74.3 74.3
68.7 68.6 68.7 68.7 68.8 68.8 68.6 78.7 75.7 78.8 75.4 76.3 78.7 77.0 72.9 73.0
67.2 67.2 67.4 67.3 67.3 67.2 67.2 80.8 80.4 80.2 79.6 80.0 81.1 78.9 154.8 154.8
3.7 43.6 34.1 51.1 40.4 69.7 46.2 4.4 43.4 33.8 51.0 40.6 70.1 70.3 51.1 33.9
81.8 81.2
82.4 81.8
79.3 78.2
72.1 71.5
6.1 45.0
C-6'
C-1
61.4 61.2 61.2 61.2 61.2 61.2 61.4' 61.2' 61.4 61.4 61.4 63.6 61.2 60.6 6.0 62.0 44.6 61.1 36.0 61.7 53.6 61.4 42.7 61.6 6.0 64.9 71.3 66.0 87.0 62.0 87.0 61.8 62.9.60.5 (Cl, 6) 3.9 62.5 43.1 60.2
"A personal communication from the authors indicates that the assignments for these two compounds were inadvertently inverted in the original paper. bMeasured at 50.3 MHz in chloroform-dreferenced to internal Me,%. These assignments might have to be reversed. weaswed at 50.3 MHz in chloroform-d-referenced to the central peak of the chloroform-dtriplet (76.9 ppm). 'Measured in chloroform-dat 75.5 MHz, referenced to internal Me,Si. 'Additional signals at 6 170.2, 170.1, 169.6, 169.5, 168.9 (5 carhnyl), 132.6 (NCS), 20.6, 20.5 (2 C), 20.3 and 20.2 (5 Me) % 170.8 (CO), 109.4 (CMe,, dioxolane), 27.7,26.1 (2 Me), 20.7 (COCH,). hMeasuredat 50.3 MHz in chloroform-d.
C-1'
Ref.
60.7 60.6 61.0 60.7 61.0 61.2 61.2 62.5 62.2 62.5 62.6 62.8 62.6 63.6 62.3 62.3
119 119 119 119 119 147 150 119 119 119 119 119 147 147 119 119 151 119 119
64.2 63.9
TABLE XIX 'H NMR Spectra of Di-o-fructose Dianhydride Derivatives
Proton Chemical Shift (ppm) H-la Compound 55"
63"
64" 67'.'
J,,', 4.21 dd 12.3 4.49 d 12.4 4.46d 12.3 3.81 d 12.5
H-lb
H-3 J3.4
3.80 dd 4.28 dd 2.5 3.82d 4.30d 2.4 3.91 d 4.35 d 2.8 3.67 d 3.70d 6.2
H-4
H-5
H-6a
H-6b
545
J5.b
J5.a
JSr6b
4.56 dd 0.7 4.54 dd 0.6 4.55 dd 0.7 4.25 t 6.2
4.72 bs 4.08 ddd 3.86 d 1.2 0 8.6 4.79 ddd 4.06 dd 3.83 d 0 1.3 8.9 4.68 q 4.05 dd 3.81 d 1.3 0 9.0 4.14 ddd 3.98 dd 3.84 dd 13.1 1 .o 2.5
"Measured at 400 MHz in D,O (internal acetone 3 1.1 ppm). *Measured at 500 MHz in chloroform-d. 'Additional signal at 6 1.42 and 1.29 (2 s, each 3 H. 2 Me).
H-l'a Jl'%l'b
4.42 d 12.2 4.24 d 12.3 4.17 d 12.3
H-l'h
H-3'
H-4'
H-5'
H-6'a
JY.4
J45'
55f.6'8
J5'4.b
3.63 dd 3.69 dd 9.9 3.70d 3.99d 8.0 4.06 d 4.28 d 2.8
4.02d 4.13 md 3.4 1.3 4.22 dd 4.03 ddd 6.7 5.1 4.06 dd 4.59 ddd 1.5 0.9
3.97 dd 2.0 3.59 dd 6.7 4.13 dd 0
H-6'b J6t%wb Ref. 3.83dd 12.7 3.52dd 10.8 3.99d 9.0
147 141 147 151
TABLEXX 'H NMR Spectra of Fructose Components of Derivatives of Per-0-acetyl Derivatives of Di-D-fructose Dianhydrides Proton Chemical Shift (ppm) H-la Compound
H-lb
J,,,, 4.30 d 11.7 4.27 d 11.7 4.34 d 11.7 4.25 d 11.7 4.29 d 11.7 4.10 dd 11.7 3.99 d 11.6 4.08 d 11.8 4.08 d 11.8
3.89 d 3.89 d 3.89 d 3.88 d 3.90 d 3.84 d 3.66 d 3.71 d 3.73 d
H-3
H-4
J3,4
J4,5
5.59 d 1.8 5.55 d 1.6 5.61 d 1.9 5.53 d 1.4 5.64 d 1.8 4.58 d 2.2 5.28 d 1.1 5.18 d 1.9 5.14 d 1.5
5.1 1 dd 5.8 5.29 dd 5.5 5.40 dd 5.2 5.22 dd 6.0 5.37 dd 5.2 4.71 dd 0.5 4.75 dd 4.8 4.77 dd 5.6 4.93 dd 5.1
H-5 4.02 ddd 3.7 4.16 q 4.2 4.42 ddd 4.4 4.11 td 2.7 4.27 q 5.2 4.29 bs 1.o 3.53 m 3.7 3.95 dd 4.5 4.15 td 4.6
H-6a
H-6b
H-l'a
J5.6b
J6a,6b
Jl'a,l'b
H-l'b
3.47 dd 3.35 dd 3.94 s 6.9 10.8 3.99d 3.93 d 3.79 d 4.2 11.7 3.14dd 3.04dd 4.04d 3.93 d 6.8 13.9 11.7 3.49 dd 3.36 dd 3.98 s 5.2 13.5 3.70 rn 4.09d 3.95 d 11.7 5.2 3.42dd 3.49d 4.49d 3.80d 11.7 0 8.5 3.24 d 3.76d 3.71 d 13.4 3.7 3.45 dd 3.36 dd 3.99 d 3.54 d 5.6 12.1 11.8 3.77 dd 3.71 dd 4.02 d 3.58 d 11.8 5.1 12.5
H-3'
H-4'
H-5'
H-6'a
H-6'b
JY.4
54.5.
JS'.6a
J5'.6b
J6'p6'b
5.78 d 10.6 5.77 d 10.6 5.74 d 10.6 5.73 d 10.6 5.79 d 10.6 5.76 d 10.6 5.55 d 10.6 5.10 d 6.5 5.13 d 6.5
6.00 dd 3.4 5.98 dd 3.4 5.93 dd 3.4 5.91 dd 3.4 5.94 dd 3.4 5.97 dd 3.4 5.73 dd 3.4 5.31 dd 4.7 5.35 dd 4.8
5.64 ddd 1.7 5.64 ddd 1.7 5.64 ddd
Ref' 119
1.6 5.67 m
3.65 dd 3.52 dd 1.4 13.0 3.69 dd 3.57 dd 1.4 13.0 3.72 dd 3.63 dd 1.4 3.72 dd 3.63 dd 1.3 13.0 3.70 m
5.63 ddd 1.8 5.42 ddd 1.8 4.18 ddd 6.5 4.18 ddd 5.6
3.68 dd 1.6 3.43 dd 1.3 3.43 dd 7.9 3.74 dd 7.3
147
2.0 5.64 ddd
3.58 dd 13.1 3.30 dd 13.1 3.32 dd 10.3 3.65 dd 12.1
119 119 119 119
150 119 119
TABLE XX (continued) Proton Chemical Shift (ppm) H-la Compound
J,,,,
(56)"
4.00d 11.8
6(y:
4.05 d 11.9 4.07d 11.9 4.32d 11.8 4.27dd 12.1 4.02d 12.1 3.98d 11.9 3.85d 12.6
628 63/
Mf 65R
66' 67f
H-lb
H-3
H-4
H-5
H-6a
H-6b
H-l'a
J3,4
J45
J5,6a
JS,6b
J6a.6b
Jl'a,l'b
3.61 d
5.08d 2.0
4.90dd 5.9
4.08 td 2.7
3.73d
5.14d 1.7 5.18d 1.7 4.38d 2.2 4.37dd 2.4 5.17d 1.5 5.13d 1.9 5.05d 7.6
4.84dd 5.3 4.77dd 5.3 4.84d 0 4.81dd 0.5 4.85dd 5.3 4.91 dd 5.9 4.21 m
4.08 td 2.7 4.05q 5.3 4.58bs 1.o 4.54bs 1.1 4.10td 2.6 4.08 td 2.8
3.64d 3.70d 3.74d 3.75d 3.67d 3.47 d
2.80 rn 5.9 3.53 dd 3.39dd 5.3 13.4 3.62dt 3.50dt 5.3 13.6 3.89dd 3.69d 0 8.6 3.84dd 3.59d 0 8.6 3.56dd 3.41dd 5.3 13.4 2.71 m 5.9 4.00 rn
H-l'b
H-3'
H-4'
H-5'
H-6'a
H-6'b
JY.4'
J45'
JS',6s
JS',6'b
J6a,6b
3.98 d 11.8
3.49d
5.03 d 6.3
4.02d 11.9 3.99d 11.8 4.10d 12.1 4.00d 11.8 4.06d 12.0 4.05d 12.1
3.55 d 5.12d 6.9 3.56d 5.10d 6.3 3.49d 5.10d 6.4 3.69d 4.12d 2.6 3.60d 5.06d 7.5 3.58d 5.05d 7.4
5.32dd 4.7
4.09 td 4.7
5.26dd 5.4 5.22dd 4.9 5.34dd 4.5 4.98dd 3.4 5.92ddd
4.07ddd 4.1 4.04ddd 5.3 4.18rn 6.4 4.18111
5.92ddd
2.80 rn 7.4 3.54dd 3.46dd 7.7 13.1 3.66dt 3.41ddd 7.7 13.6 3.46dd 3.35dd 8.0 10.4 3.96 s
J4..,.a=2.2 4.55dd J4',6.b= 1.8 J,.,,.,=2.2 4.54dd J4',6,b= 1.8
"A personal communication from the authors indicates that the assignments for these two compounds were inadvertentlyinverted in the original paper. bMeasuredat 200 MHz in benzene-d,, reference to internal Me$. 'Measured at 400 MHz in benzene-d,, referenced to internal Me4Si. dMeasured at 30.0 M H z in chloroform-d. 'Additional signals at 6 1.82, 1.73, 1.72, 1.66, 1.52 (5s. each 3H, 5 Me). 'Measured at 200 M H z in chloroform-d,referenced to internal Me& RMeasuredat 400 M H z in chloroform-d,referenced to internal Me4Si.
4.17dd 2.7 4.14dd 2.8
Ref' 119
119 119 147 147 119 119 151
ADVANCES IN CARBOHYDRATE CHEMISTRY AND
BIOCHEMISTRY, VOL. 52
SUGARS AND NUCLEOTIDES AND THE BIOSYNTHESIS OF THIAMINE B Y SERGEDAVIDAND BERNARD ESTRAMAREIX Institur de Chimie Mofdculaire dOrsay, UniversitC de Paris-Sud Bt 420, F-91405 Orsay Cbdex, France
I. Introduction . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . ........................ 1. Problems in the Study of Thiamine Biosynthesis . . . . 2. Biosynthesis of Thiamine Diphosphate from Thiazole and Pyrimidine ....................................... Precursors . . . . . . . . . . . 3. Methods for the Exami etabolites . . . . . . . . ..... 11. 1-Deoxy-D-fhreo-pentuloseas the Precursor of the ..................... in Escherichia coli Cells and Spinach Chloroplasts 1. Synthesis by Whole Cells of Escherichia coli . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 2. Synthesis in a Cell-free Extract of Spinach Chloroplasts . .., . .. ...... . .. .. . .... . .. 111. Chemistry and Biochemistry of I-Deoxy-D-lhreo-pentulose. . . . .
..................... 3. Problems of Biosynthesis . . . . 4. Stray Thiazolic Metabolites w 5 . 1-Deoxy-D-threo-pentulosein
............. ........................
Enterobacteria . . . . . . . . . ................. 1. Derepression of the Sy 2. From Imidazole to Pyr 3. Preparation of Specifically Labeled Samples of 5-Amino- 1-(P-~-ribofuranosyl)imidazole(ARs) ............................................. .......... ....................................... 4. Biosynthetic Studies . . . . . . ..................... VI. Pyramine Synthesis in Yeasts . . . . . . . . . . . . . . . ........... VII. The Distribution of the F 1. Biosynthesis of Pyramine ..................................... 2. Biosynthesis of Thiaz VIII. Conclusion . . . . . . . . . . . . ....................................... ..................... References . . . . . . . . . . . . . . . . . . . .. . .. . . . . . .. . . ..
0096-5332D7 $25.00
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268 268 269 27 1 275 275 211 277 277 278 282 284 287 288 288 292 292 293 295 300 303 305 305 306 306 307
Copyright 0 1997 by Academic Press. All rights of reproduction in any form reserved.
SERGE DAVID AND BERNARD ESTRAMAREIX
268
I. INTRODUCTION
1. Problems in the Study of Thiamine Biosynthesis Thiamine (1, Scheme l), isolated in 1926 and first synthesized in 1936, is the oldest known vitamin. Nevertheless, in spite of its ubiquitous presence in living cells, progress has been very slow in elucidating its biosynthesis. Its concentration in cells is extremely low, of the order of 30 ng per gram of dried cells, and it does not accumulate in any wild organism. This meant that, in experiments with radioactive potential precursors, a minute quantity of thiamine had to be extracted from a huge contaminating background, so that spurious radioactivity originating from impurities was not easily separated from this metabolite. This difficulty was not properly realized in early work. It was the source of many erroneous conclusions in the early literature, and a cause of much perplexity among careful research workers. The detailed refutation of these early reports is outside the scope of this chapter, but can be found elsewhere.'
1
R
R'
1 Thiamine
H
H
2 Diphosphate
H
PO(OH)-O-P03H2
CH2OH
PO(OH)-O-P03H2
3 (2-Hydroxyethy1)thiamine diphosphate
6 CH3
4
5
SCHEME 1.-Thiamine and its two derivatives present in cells. The numbering of the atoms of pyramine (4) and thiazole (5) adopted in this chapter.
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
269
Still more confusion plagued early researches, when it was not realized that the biosynthetic routes to thiamine in prokaryotes and eukaryotes are quite different, a fact not expected at the outset. Thus, evidence collected from the study of yeast could not be transposed to bacteria, and vice-versa. For instance, formate is a most efficient precursor of one of the carbon atoms of the pyrimidine part of thiamine (pyramine), both in yeasts and enterobacteria, but incorporates at C-2 in bacteria and at C-4 in yeast. However, as is briefly covered in Section VIII, this dichotomy of pathways might have a deep significance in the perspective of biochemical evolution during primitive life on Earth. All chemical information not involving carbohydrates, but nevertheless necessary to the understanding of this chapter, is gathered in this Introduction, and is found in the following subsections.
2. Biosynthesis of Thiamine Diphosphate from Thiazole and Pyrimidine Precursors Thiamine is present in cells as the free form 1, as the diphosphate 2, and as the diphosphate of the hydroxyethyl derivative 3 (Scheme 1) in variable ratio. The component heterocyclic moieties, 4-amino-5-hydroxymethyl-2-methylpyrimidine (4) and 4-methyl-5-(2-hydroxyethyl)thiazole(5) are also presented in Scheme 1, with the atom numbering. This numbering follows the rules of nomenclature of heterocyclic compounds for the ring atoms, and is arbitrary for the substituents. To avoid the use of acronyms, compound 5 is termed as “the thiazole of thiamine” or more simply “the thiazole.” This does not raise any ambiguity because unsubstituted thiazole is encountered in this chapter. Other thiazoles are named after the rules of heterocyclic nomenclature. Pyrimidine 4 is called “pyramine,” a well established name in the field. A detailed account of the present status of knowledge on the biosynthesis of thiamine diphosphate from its heterocyclic moieties can be found in a review by the authors.’ This report provides only the minimal information necessary for understanding the main part of this chapter (Scheme 2). Thiamine can be considered to be the product of the quatemization of 4methyl-5-(2-hydroxymethyl)thiazole(5) by an active derivative of 4-amino-5(hydroxymethyl)-2-methyl pyrimidine (4) (Scheme 2). In living cells, pyramine can be activated by conversion into the diphosphate 7, via monophosphate 6, and the substrate of the enzyme responsible for the quaternization is not the thiamine thiazole, but its phosphate 8. The product of the condensation, thiamine phosphate (9),is finally converted into diphosphate 2- the biochemically active derivative-by hydrolysis to free thiamine, followed by diphosphorylation, or more directly, in some cases. Enzymes are known for all of the steps depicted in Scheme 2, and adenosine triphosphate (ATP) is, as usual, the phosphate donor. Now a cautionary note is necessary. This chapter covers with the biosyntheses of thiazole and pyramine. From a glance at Scheme 2, one might conclude that
4
6 CH3 I
5
8
2
SCHEME 2.-Phosphorylations and condensation in the biosynthesis of thiamine pyrophosphate.
9
1
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
27 1
organisms able to synthesize thiamine (autotrophic) first fabricate the component heterocycles, then condense them together, according to the reactions described in Scheme 2. Indeed, in most, if not in all cases, organisms unable to synthesize thiamine because they are blocked in the synthesis of either thiazole or pyrimidine can utilize these molecules, when externally supplied, to the synthesis of thiamine. Traditional biochemical thinking would consider them as true intermediates. Consideration of mutants led to the conclusion that completely assembled pyrimidines, that is, pyramine (4), its phosphate (6), or its diphosphate (7) are intermediate. This is not true of the thiazole moiety. In other terms, although the participation of thiazole to the biosynthesis of thiamine, as described in Scheme 2, might be undoubtedly demonstrated when external thiazole is supplied, there is no stringent proof that, in autotrophic cells, the precursors of the thiazole of thiamine are not directly assembled on the pyrimidine, without preliminary formation of free thiazole or thiazole phosphate. In all the experiments, the extracted metabolite was thiamine, so they could be more properly described as investigations on the biosynthesis of the thiazole moiety of thiamine. But, for the sake of brevity, the wording “biosynthesis of thiazole” is used throughout this chapter.
3. Methods for the Examination of Labeled Metabolites
a. Cleavage of the Bond Between Pyrimidine and Thiazole.-Treatment of thiamine in aqueous solution with sodium hydrogensulfite achieves a quantitative separation of the two heterocyclic moieties to produce thiazole (which remains in solution) and the sodium salt of the sulfonic acid 10 (which precipitates slowly). The thiazole can be extracted from the aqueous mother-liquor with chloroform (Scheme 3).* Preliminary investigations suggested that the pyrimidinesulfonic acid would not be easily amenable to further degradations (see later). Another approach to the cleavage is depicted in Scheme 4. Thiamine was first deaminated with 6N HCl to the pyrimidone analogue 11, which was treated with thioglycolic acid to produce the substituted thioglycolic acid 12. This was hydrogenolyzed to 2,5-dimethyl-4-hydroxypyrimidine(13) with Raney nickel (Scheme 4).3Alternatively, in experiments in which pyramine was excreted in the medium, this metabolite was extracted and then deaminated with 6N HCl to produce 2-methyl-4-hydroxy-5-hydroxymethylpyrimidine (14). The benzyl-type hydroxy function in 14 was hydrogenolyzed on palladized charcoal to the same dihydropyrimidone 13 (Scheme 4).4v5 b. Degradation of the Thiazole.-Isolation of the C-2 carbon atom is described in Scheme 5. The thiazole was first quaternized with methyl iodide, and the thiazolium derivative was reduced by sodium borohydride to a thiazolidine (16), which was decomposed with mercuric chloride. The C-2 carbon atom of thiazole was separated as formaldehyde, and readily isolated and analyzed as the
I
0
+
P x
I" 0
s G I
SUGARS, NUCLEOTIDES. THIAMINE BIOSYNTHESIS
5
213
15
16 SCHEME 5.--Isolation of carbon C-2 of the thiamine thiazole.
dimedone derivative.6 In a more-complete series of degradation experiments, oxidative cleavage of the 2-hydroxyethyl side-chain of thiazole 5 gave 4-methyl5-formylthiazole (17) (Scheme 6). Oxidation of the phthalimido derivative 18, prepared as indicated in Scheme 6, separated C-CH, as acetic acid, and C-5 and the hydroxyethyl side-chain in the form of a derivative of p-alanir~e.~.*
5
17
[>CHZCHZ
18 SCHEME6.-A degradation of the thiazole molecule, allowing the estimation of the labeling of each carbon atom of the five-carbon chain in a biosynthetic sample.
SERGE DAVID AND BERNARD ESTRAMAREIX
214
CH3 13
19 hydrolytic ring opening of pyramine, producing fragments in which the specific activity of each carbon can be estimated.
SCHEME7.-The
c. Degradation of Pyramine.-Pyrimidine 13 is inert toward bases, but the pyrimidinium cation 19, obtained by the quaternization ,of both nitrogen atoms with methyl iodide, is more labile. Treatment with a hot, strong base produced an equimolecular mixture of the salts of formic, acetic, and propanoic acids. These acids were recovered by steam distillation after acidification, and separated from each other. They correspond respectively to C-6, to C-2, and CH,, and to C-4, C-5, and C-8 of pyramine (Scheme 7).' Micromethods for the sectioning of such acids into one-carbon fragments have existed since the early days of tracer work. A more-recent version of this degradation involves the direct quaternization of the pyrimidylmethylsulfonic acid 10 (Scheme 3) and 3-sulfopropanoic acid is finally isolated, instead of propanoic acid.I0
8 and 9 summarize the d. Mass-spectrometric Fragmentation.-Schemes fragmentations of derivatives of thiazole and pyramine, which are of relevance to this chapter. Thiazole was first derivatized into the trifluoroacetic acid ester." The ethylthio analogue of pyramine in Scheme 9 was prepared by the cleavage of thiamine diphosphate by ethanethiol.l*
m/z 125 m/z 239 m/z112 SCHEME. 8.-Fragmentation pattern of the trifluoroacetic acid ester of the thiazole of thiamine in the mass spectrometer.
SUGARS, NUCLE(YTIDES, THIAMINE BIOSYNTHESIS
215
H
H
m/z 184
m/z 123
m/z 81 SCHEME9.-Fragmentation
in the mass spectrometer of an ethylthio derivative prepared from pyra-
mine.
CHAIN II. 1-DEOXY-D-ZhWO-PENTULOSE AS THE PRECURSOR OF THE FIVE-CARBON OF THIAZOLE IN ESCHERICHIA COW CELLS AND SPINACH CHLOROPLASTS
1. Synthesis by Whole Cells of Escherichia coli The organism utilized is a mutant of E. coli blocked in the synthesis of aromatic amino acids before the shikimate step. Cells are first grown in the presence of adenosine, a technique that temporarily derepresses the system of en-
216
SERGE DAVID AND BERNARD ESTRAMAREIX
zymes involved in the biosynthesis of thiamine such that they become able to synthesize thiamine in much larger amounts. No growth is possible in the absence of one of the three aromatic amino acids and the cells are in the socalled resting conditions; in the presence of pyramine, these cells can produce thiamine only when L-tyrosine is added to the medium. The use of L-tyrosine (uniformly or specifically labeled), and the degradation of the biosynthesized thiazole (according to Scheme 5 ) , showed that the C-2 carbon atom of L-tyrosine was the precursor of C-2 of thiazole, the other carbon atoms being lost.13 With L-(i5N)tyrosineas precursor, it was shown by mass-spectrometric examination of thiazole, according to Scheme 8 that the nitrogen atom of L-tyrosine was the precursor of the nitrogen atom of the thiazole; thus, the C-N unit was introduced as a whole." It was discovered afterward that the aromatic part of L-tyrosine is excreted in the form of 4-hydroxybenzyl alcoh01.'~Finally, there are strong indications that L-cysteine is the sulfur donor. Is- l9 The problem remained of the origin of the five-carbon unbranched chain of the thiazole. Because three carbons out of five were functionalized suggests a sugar precursor. The two 1-deoxy-D-pentuloses, 1-deoxy-D-erythro-pentulose (20), and 1-deoxy-D-threo-pentulose (21) were prepared trideuterated in the methyl group. Non-growing, washed cells of E . coli, derepressed for the biosynthesis of thiamine, were incubated in the presence of D-glucose and L-tyrosine and either pentulose 20 or 21.The incorporation of deuterium into thiazole was measured by mass spectrometry (see Scheme 8). The label of the D-threo compound was found in more than 40% of the thiazole biosynthesized.20On the other hand, the incorporation of the label from the D-erythro epimer was insignificant. The next step was to show that the D-threo epimer was incorporated without rupture of the carbon chain, by incubation in the presence of the molecule labeled at both ends with three deuterium atoms on the methyl and one of the C-5 carbon atom. The observed fragmentation of the trifluoroacetate of the thiazole biosynthesized under these conditions indicated that about 20% of the molecules carried four deuterium atoms with the anticipated distribution, corresponding to that in the precursor.21.22The evidence from all the experiments just described is summarized in Scheme 10.
CH3
CH3
co
co
I
I HCOH
I
HCOH
I
CHpOH
20
I
I HO C H
I
HCOH
I
CH,OH 21
SUGARS. NUCLEOTIDES, THIAMINE BIOSYNTHESIS
277
CHNH,
I
OH
SCHEME10,-The
CO,H
assembly of precursors in the building of the thiamine thiazole in Enterobacteria.
2. Synthesis in a Cell-free Extract of Spinach chloroplast^^^ An extract from the soluble stromal proteins of purified and intact spinachleaf chloroplasts was prepared by lysis of the cells in buffer, centrifugation of the suspension of broken cells, and concentration of the supernatant with removal of insoluble material. This extract contained all of the enzymes involved in the condensation of the cyclic moieties of thiamine, thiazole, and pyramine. Thus, the synthesis of thiamine in this extract following the addition of pyramine and putative precursors was a proof that the system had the possibility of building the thiazole. It was found that L-tyrosine was the donor of the C-2 carbon atom of thiazole, as in E . coli. Also, as in E. coli cells, addition of I-deoxy-D-threo-pentulose permitted synthesis of the thiamine structure. The relevant enzymes were localized by gel filtration in a fraction covering the 50- to 350-kDa molecularmass range. This fraction was able to catalyze the formation of the thiazole moiety of thiamine from 0. l -mM l -deoxy-D-threo-pentulose at the rate of 220 pmol per mg of protein per hour, in the presence of ATP and Mg2+. 111. CHEMISTRY AND BIOCHEMISTRY OF 1 -DEoXY-D-threo-PENTULOSE
1. Isolation from Culture Broths of Streptomyces hygroscopicus and Characterization The antibiotic-producing organism was a new isolate, identified as Streptomyces hygroscopicus (UC-5601). Pentulose 21 was present in the butanol extract of a fermentation broth that had been first concentrated and saturated with ammonium sulfate. At this step, TLC and subsequent bioautography, using M y cobacterium avium (UC-159) as the test organism, revealed the presence of hygromycin A (RF 0.20) and a new activity (RF 0.46). A fairly laborious procedure allowed the isolation of the new active compound, as a crystalline material, in a yield of 442 mg from a 5000-liter fermentation broth; it had mp 61 -63°C [a], +46" (c I , water). The infrared spectrum was indicative of a compound having a high percentage of hydroxyl functions. More noteworthy was a very pronounced
278
SERGE DAVID AND BERNARD ESTRAMAREIX
carbonyl absorption at 1710 cm-' (mineral oil mull). The crystalline sugar was found to inhibit in vitro the growth of the test strain of M. avium at 1 mg/mL. It was inactive at 20 mg/mL against all other organisms tested.24Structure 21 was ascertained from the mass spectrum, showing a peak at mlz 135 with the composition C,H, ,O, (M+ + 1), from the proton NMR spectrum with a singlet at 2.15 ppm, suggesting an acetyl moiety, and from the composition of the mixture obtained by hydrogenation in the presence of a platinum catalyst. This produced a mixture (presumably 22 and 24) that was resolved after per-0-acetylation, to yield, as the major component, the crystalline D-lyxitol peracetate (23), and as the minor component, the oily D-xylitol peracetate (25). The 'H NMR spectra of 1-deoxy-D-threo-pentulose in D,O or dimethyl sulfoxide-d, indicated a strong predominance of the open-chain form in these solvents (80%).The tetraacetate of 21 was found to exist in the keto form excl~sively.~~ Synthetic work, published later, confirmed and completed these first data: 1deoxy-D-threo-pentulose is a crystalline compound, mp 61 -63°C (Ref. 24), mp 62-63°C (Ref. 26) (from ethyl acetate). It exists in the solid state as the openchain ketone, as indicated by its strong carbonyl absorption at 1710 cm-' in Nujol m ~ 1 1 .The ~ ~reported , ~ ~ optical rotations for 1% solutions in water are somewhat discordant, the figures for [a& being +46", +34", +33.6", and +22.4", in Refs. 24, 22, 26, and 27, respectively. These discrepancies could be the consequence of variation in the proportions of tautomers in solution from preparation to preparation. The 'H NMR spectrum in D,O indicates the presence of a mixture of tautomers, with methyl signals at 6 1.35, 1.39 (cyclic anomers) and 2.21 ppm (open chain) in the ratio 16: 15:67 (Ref. 27). The figures given in the first report24 are 6 1.23, 1.31, 2.15, apparently in D,O. Other reported chemical shifts, 1.64, 1.69, and 2.50 are 0.30 ppm higher, which suggests a different point of origin on the 6 scale.26The open-chain tautomer could not be detected in CD,OD solutionz7;the spectrum showed only two methyl signals, at 6 1.27 and 1.32. Carbon I3C NMR confirmed these interpretations, showing a carbonyl signal at 6 216.7 ppm in D20, and two signals at 110.4 and 105.9, in the relative ratio of 1:1, in CD,OD. The L enantiomer, 1-deoxy-L-threo-pentulose has the same melting point, opposite optical rotation, and was claimed to display the same NMR characteristics.26It is well known that deoxygenation in the vicinity of the carbonyl enhances the proportion of open-chain form in a ketonic sugar.
-
y
3
ROCH
I
ROCH
1
H COR
I
CHzOR
7% HCOR
I
ROCH
I
HCOR
I
CHPOR
22 R = H
24 R = H
23 R = A c
25 R = A c
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
GJ a YS - Y S HCOH
CO
H'?y,CMe, CH20
?\/CMe2 CH2O
I
I
26
27
219
a
YS
HOCH
I
?4CMe2 CH20 28
'?H3
co I
RCR'
I
CH20 29 R = H R ' = O H
30 R = O H R ' = H
SCHEME1 1. -Synthesis
of 1-deoxy-D-rhreo-pentulosefrom o-glyceraldehyde.
2. Chemical and Preparative Enzymic Syntheses Derivatives of 1-deoxy-L-rhreo-pentulosewere prepared in 1965 (Ref. 28) and 1972 (Ref. 29), but chemists were interested in the synthesis of the D-enantiomer only after it had been found to be a precursor of the thiazole of thiamine in enterobacteria. One synthesis20began by condensation of the propylene dithioaceta1 of acetaldehyde with 2,3-O-isopropylidene-~-glyceraldehyde. This produced mainly the D-erythro dithioacetal26 (Scheme 1l), which was separated, and oxidized to the pentodiulose derivative 27 with the Pfitzner-Moffatt reagent. Borohydride reduction produced a mixture of 26 and 28. After dethioacetalation, 1deoxy-5,6-O-isopropylidene-~-erythro-pentulose 29 and its D-threo epimer 30 were separated. They were hydrolyzed to the free sugars just before use. The labeled (l-'H,) pentuloses were prepared from the dithiane reagent, obtained from ICD, and formaldehyde propylene dithioacetal. Another synthesis, described in detail in Scheme 12, was devised specifically for the introduction of deuterium at both ends of 1-deoxy-D-threo-pentulose.2',22 Stannylene methodology was used twice, first for glycol splitting with phenyliodonium diacetate, under strictly neutral conditions (necessary to preserve the benzylidene acetal), and secondly to convert the sequence -CHOH-CD, to CO-CD, by brominolysis. The final, labeled pentulose was 1-deoxy-D-threo( 1-2H,, 5-2H)pentulose.
L
8
a
ot
8
a
ot
f
a
ot
9
I
l o r I o I o
0
I
0
~-~--o--o--o--o.np0
I
0
6 0
p 8
to a
st
-
a
‘63
s3
v1
.-
c
B
R I (I)
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
CH3
CH3
CHPOH
I
BnO CH
I
HyLCMez CH2d 31 SCHEME 13.-First
I CHOH I BnOCH
-
28 1
-
I
I I
co BnOCH
I
HC(hCMe2 AHpd
HCLCMe2 AHzd
33
32
steps of synthesis of 1-deoxy-o-rhreo-pentulosefrom diethyl tartrate.
In a third chemical synthesis (Scheme 13), the starting material was dimethyl D-threarate (tartrate), which was converted in three steps into alcohol 31, according a known procedure. The oxidation of 31 to the aldehyde with the Dess-Martin reagent and reaction with methylmagnesium bromide produced the alcohol (32), which were converted into the ketone 33, again with the Dess-Martin reagent. The target pentulose was obtained after conventional deprotection steps.30 Finally, the necessity arose for the synthesis of pentulose 21, labeled with I3C on the central carbons, C-2 and C-3, for an independent biosynthetic study, which is reported in Section III.5.27The doubly labeled ester 34 (Scheme 14) is readily available by a Wittig-Homer condensation of benzyloxyacetaldehyde with commercially available triethylphosphono-(1,2-I3C2)acetate.Chirality was introduced by the reduction of ester 34 to the allylic alcohol, which produced the chiral epoxide 35 by the Sharpless epoxidation procedure. This was converted into the tetrose 36, and thence, into the protected pentulose 37 by the usual sequence of Grignard reaction and oxidation. Enzymic syntheses are considered next. Xylitol is a substrate for sheep-liver L-iditol dehydrogenase, a NAD-linked enzyme. 1-Deoxy-D-xylitol, prepared by Raney nickel reduction of D-xylose diethyl dithioacetal in a 27% overall yield from D-xylose, was also reported3' to be a substrate, although with a higher Km and lower Vmax. The product was assumed to be I-deoxy-D-threo-pentulosebecause of the appearance of a yellowish fluorescent spot when a chromatogram was sprayed with acidic 3,5-aminobenzoic acid, resembling that formed from 1-deoxyfructose. There was no more-rigorous characterization. More significant from the preparative point of view is the enzymic procedure described by Yokota et ~ 1The. deoxypentulose ~ ~ derivative is formed according to Reaction 1: (R,S)-Acetoin + D-GIyceraldehyde +Acetaldehyde 1-Deoxy-D-threo-pentulose ( I )
+
282
SERGE DAVID AND BERNARD ESTRAMAREIX
H
I
BnO/\C+
I
C'C02Et
--
CH20Bn
CH20Bn
I
/T
I
p - q --c
HC-0
I
H
CH20H 34
HC-0-CMe,
I
CHO
36
35
CH20Bn
I
YC-9 HC-0 -CMe,
I
co I
CH3
37 SCHEME 14.-First steps of the synthesis of I-deoxy-D-threo-pentulose labeled with ''C on C-2 and c-3.
The reaction was catalyzed by a partially purified enzyme preparation from a mutant of Bacillus pumiflus (see the next subsection). From 1 g of D-glyceraldehyde and 1 g of acetoin, 0.67 g of pure crystalline 1-deoxy-D-threo-pentulose was obtained in one operation. The sugar was fully characterized. With L-glyceraldehyde as substrate, the same extract catalyzed a half-gram scale synthesis of 1-deoxy-L-threo-pentulose.
3. Problems of Biosynthesis The next problem concerns how 1-deoxy-D-threo-pentuloseis synthesized in cells. Some experiments strongly suggest that it results from the coupling of a two-carbon and a three-carbon fragment. Thus, the distribution of the deuterium atoms incorporated from (Me-2H,)pyruvate in the thiazole of thiamine indicated that the fragment C-CH, is derived from pyruvate, a conclusion confirmed by studies of incorporation with (6,6'-2H2)glucose, (5,6,6'-2H,)glucose, and (U-13C)glucose.32 Moreover, l80from (3-2H2'80)glycerolincorporated simultaneously with deuterium (Scheme 15).,, It was concluded that C-5 and the hydroxyethyl side-chain are closely connected to glyceraldehyde phosphate. All this evidence suggested the existence in cells of Reaction 2, which would produce the phosphate of 1-deoxy-D-threo-pentulose.This could be a precursor of thiazole phosphate, a known precursor of thiamine (Scheme 2).
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
283
-I
CH20H
D-Glucose
-
CHOH
I
CH20H
SCHEME15.-Pyruvate and glucose (or glycerol) as precursors of the five-carbon chain of the thiazole of thiamine in E. coli.
CH,COCO,H
+ D-glyceraldehyde 3-phosphate
-+
1-deoxy-D-threo-pentulose5-phosphate + CO,
(2)
On the other hand, as mentioned in the preceding subsection, a preparativescale enzymic synthesis of I -deoxy-D-threo-pentulose can be achieved, according to Reaction 1, in the presence of an extract of B. pumilus. Obviously, this raises the question of the relevance of Eq. 1 to the production of the pentulose in microorganisms. Acetoin in Reaction 1 could be replaced by 3-hydroxy-3methyl-2-butanone (then the by-product is acetone). More interestingly, it can be also replaced by pyruvate, then the pentulose is synthesized according to Reaction 3: CH,COCO,H
+ D-glyceraldehyde--* 1-deoxy-D-threo-pentulose+ CO,
(3)
However, in this case, glyceraldehyde 3-phosphate was not a substrate. Reactions I or 3 have been observed in a number of microorganisms. They could be extended to higher aldoses. The corresponding enzyme(s) require(s) thiamine diphosphate and Mg2+for activity. A closer examination of the extracts revealed that Reactions 1 and 3 were catalyzed by two different enzymes, which could be separated by chromatography of an extract of B. subtilis on a Sepharose column. The enzyme responsible for Reaction 3 is analogous to pyruvate dehydrogenase. This well-known enzyme catalyzes the transfer of acetaldehyde from a variety of donors to many substrates other than aldoses. However, in the case of B. subtilis, only pyruvate can be utilized with aldoses as acceptors. Pyruvate dehydrogenase can be associated with other enzymes to produce an extensive system, the socalled pyruvate dehydrogenase complex. A preparation of this complex from bovine heart was also active in catalyzing Reaction 3.34 The other enzyme isolated was analogous to acetoin dehydrogenase. In contrast, another found that extracts of E . coli contained a mixture of pentulose phosphates at a concentration near 0.3 nmol per mg of the dry weight of cells. The sugars were estimated by gas chromatography-mass spectrometry after treatment of the extract with phosphatase followed by silylation, or borohydride reduction and acetylation. Furthermore, a partially purified preparation from these extracts catalyzed the synthesis of 1-deoxypentulose
284
SERGE DAVID AND BERNARD ESTRAMAREIX
phosphates from glyceraldehyde 3-phosphate at the rate of 0.3 mmol per hour per mg of protein. Mixtures of erythro and rhreo configurations were obtained. The relevance of all these experiments to the biosynthesis of thiamine is not obvious. A mixture of configurations is obtained in amounts far exceeding the needs for thiazole synthesis; the reactions appear disconnected from it, as conditions known to alter thiamine biosynthesis, by repression or inhibition, failed to change the results. The foregoing experiments with bacterial extracts appear to rule out the involvement of pyruvate dehydrogenate complex in the biosynthesis of 1-deoxy-Dthreo-pentulose. Intervention of this complex was rigorously excluded in the case of chloroplast^.^^ Subsection 11.2 described the preparation of a purified extract of the stromal proteins active in the synthesis of thiazole from 1-deoxy-Drhreo-pentulose. In this system, the pentulose could be replaced by D-glyceraldehyde 3-phosphate and pyruvate, but with a 50% decrease in yield. However, the molecular-weight range of the most active fraction, 50 to 350 kDa, indicates that the whole pyruvate dehydrogenase complex (M>lo6) cannot be involved in this synthesis. It does not exclude the possibility that a fraction of the whole complex catalyzes the synthesis of the pentulose phosphate from D-glyceraldehyde 3-phosphate and pyruvate. As in the foregoing experiment with bacterial extracts, the activity of the pyruvate dehydrogenase complex in the chloroplast stroma, corresponding to about 3000 times the rate of thiazole synthesis, seems out of proportion with the necessities of the cell for the production of thiamine. 4. Stray Thiazolic Metabolites with Probable Deoxypentulose Origin
Some attempts were made to discover intermediates between 1-deoxypentulose and the thiamine thiazole. To this end, the incubation media of thiamineproducing bacteria were examined by bioautography. Plats were coated with thiazole-free nutrient agar to which had been incorporated cells of E . coli mutant (26-43)-which can only grow when supplemented with thiazole-and triphenyltetrazolium chloride as a growth indicator. E . coli cells derepressed for the synthesis of thiamine produced thiamine diphosphate in the presence of suitable precursors. The incubation media were evaporated to dryness, the residue was extracted with methanol, and the methanol extract was examined by thinlayer chromatography on silica gel or cellulose plates in several solvent systems. Growth factors on these chromatograms were sought by bioautography on the agar-coated plates prepared as just described, where growth zones appeared as red spots after incubation for 12-16 hours at 37°C. This experiment indicated the presence, besides the thiamine thiazole, of two new compounds, which were ultimately proved to be one enantiomer of the thiazole glycol 39 (Scheme 16),36 and the thiazole carboxylic acid 40 (Scheme 17).37
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
38
CH=NHCONHa
285
39
OCONHAr
SCHEME16.-Synthesis of the “thiazole-glycol” 39 from the thiamine thiazole and conversion to some derivatives useful for checking the specific radioactivity of a biosynthetic sample.
Although the thiazole glycol extracted from the medium had been seen, up to this point, only as a chromatographic spot, it was nevertheless possible to guess its structure from the following evidence: radioautography of the plates indicated that it incorporated the radiocarbon of ~-[2-’~C]tyrosine and the sulfur of [35S]Na,S04,and that it lost its growth-promoting activity on treatment with periodate. The racemic thiazole glycol (39) was synthesized from the thiamine thiazole by dehydration3*to the vinylthiazole (38), followed by permanganate oxidation, and it was identical in all its chromatographic properties with the unknown from the incubation medium. A 14C-labeled sample, obtained after incubation with ~-[2-’~C]tyrosine, was mixed with 100 mg of the synthetic glycol 39. The radioactivity was not lost through all the common derivatizations indicated in Scheme 16. Obviously, the experiments do not provide the chirality of the secondary alcohol function in the incubation product. The thiazolecarboxylic acid structure (40) was also guessed in a similar way, from tracer experiments. The unknown compound was converted into the thiamine thiazole by heating at 100°C and pH 2. On paper electrophoresis, it migrated as an anion at pH 4. Tracer experiments indicated that it incorporated C-l and C-2 of L-tyrosine, and the sulfur of sulfate. The synthetic acid was prepared by carboxylation of the lithium derivative of the thiamine thiazole, and the derivatives shown in Scheme 19 were obtained by conventional methods. Again, the radioactivity of the unknown, labeled with 35Scould not be separated from structure 40, added as carrier, and the molar radioactivity remained constant through several recrystallizations and the derivatizations of Scheme 17.
SERGE DAVID AND BERNARD ESTRAMAREIX
286
40
i CH&H~OPO~HZ
AS
COzCH3
CHzCHzOH
- AS
CHpCHzOH
CHzOH
41
SCHEME17.-Synthesis 40.
and transformations of 2-carboxy-5-(2-hydroxymethyl)-4-methylthiazole
The significance of these metabolites in the biosynthesis of the thiamine thiazole in considered next. Although, from their constitution, and from the tracer experiments, the metabolites are undoubtedly the products of transformation of 1 -deoxy-D-threo-pentulose, their significance in the biosynthesis of the thiazole of thiamine is not clear. The thiazole glycol is not a product arising from a transformation of the thiazole (5) of thiamine. Reduction to this thiazole (5) occurs in dialyzed extracts of disrupted cells, in the presence of ATP, NADH, and NADPH, but only at 0.2% the rate of synthesis of the thiamine thiazole (5) by intact cells. The behavior of the thiazole glycol on plates is merely a consequence of the extreme sensitivity of the tetrazolium reagent. The same is true of the thiazole acid 40. Although discovered as a growth factor, it is unable to sustain the growth of a thiazole-deficient mutant of E . coli in a liquid medium. It does not decarboxylate in water solution at pH 7. Phosphate 41 (Scheme 17) is also biologically inactive. In any case, if there is only one metabolic route to the thiazole of thiamine, the very structures of 39 and 40 show that they cannot both be intermediates. Nevertheless, the isolation of these metabolites was interesting in two respects. First, the structure of the thiazole glycol stimulated the research of functionalized carbohydrate chains as precursors of thiazole. Second, the thiazolecarboxylic acid 40 can be secreted by derepressed cells in relatively high amounts, 0.24 nmol per mg of dried cells, which is nearly half the amount of synthesized thiamine. The presence of this free thiazolic derivative in the cells contrasts with
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
287
the absence of the thiazole of thiamine, which has not been detected, unless combined to pyramine, in the complete thiamine molecule.
5. 1-Deoxy-D-threo-pentulose in the Biosynthesis of Pyridoxol (Vitamin B6) In E . coli, the entire carbon skeleton of pyridoxol (42, Scheme 18) is derived incufrom glucose. Looking for more advanced intermediates, Spenser et and came to the conclubated appropriate E . coli mutants with ~-(U-'~C)glucose sion that intact multicarbon units from glucose are incorporated with equal efficiency, yielding the two-carbon unit C-2, C-2'; the three-carbon unit, C-3, C-4, C-4', and the three-carbon unit C-6, C-5, C-5'. l-Deoxy-D-threo-pentulose, considered to be synthesized by combining a two-carbon and a three-carbon fragment, was considered a likely precursor, and actually, deuterium from this pentulose, labeled as in Scheme 14, was incorporated into pyridox01.~~ In another experiment, a culture of E . coli mutant WG2 was incubated in the presence of ~-(U-'~C)glucose and unlabeled 1-deoxy-D-threo-pentulose. Inspection of the I3C NMR spectrum of the pyridoxol synthesized under these conditions indicated that addition of the pentulose had led to a significant decrease of the efficiency of incorporation of label into the five-carbon unit C-2', C-2, C-3, C-4, C4'. The conclusion was that this sugar lay on the route from glucose to this five-carbon unk4' Similar experiments suggested that 4-hydroxy-~-threonine(43)was an intermediate in synthesis of the three-carbon unit, C-6, C-5, C-5' (after decarboxylation). This was rigorously proved by a chemical synthesis of 4-hydroxy-~-(2,3I3C,)threonine. Incubation of E . coli mutant WG2 with this substrate produced a sample of pyridoxol that was examined by 13C NMR. The presence of doublets in the signals originating from C-5 and C-6 of pyridoxol exclusively, showed that the C-2-C-3 bond of the substrate had been incorporated intact into the predicted site (Scheme 18).42 4' H0*H20H CHpOH
CHpOH
H OH i k/ t - - H
I
OH
H3C,co
21
SCHEME18.-Biosynthesis
nine.
H3C 2
'
-
N' 1
42
43
of pyridoxol from 1-deoxy-D-rhreo-pentulose and 4-hydroxy-~-threo-
288
SERGE DAVID AND BERNARD ESTRAMAREIX
pn,
CO
I
TH3
CO
I
H COH
I I
HCOH CH20H 20 SCHEME19.-Synthesis of 1-deoxy-o-erythro-pentulose.
6. Synthesis of 1-Deoxy-D-erythro-pentulose This section is completed with a brief review of the synthesis and properties of this epimer (20) of the precursor of thiazole in bacteria. This pentulose is conveniently accessible by an unconventional route (Scheme 19). Methyl 2,3;4,6-di0-isopropylidene-a-D-mannopyranoside, readily available from methyl a - ~ mannopyranoside, is converted to the ketonic glycoside by butyllithium in 9 1% yield, following a method first published by Klemer and Rodemeyep3 and scaled up by Horton and We~kerle.4~ This was converted by means of lithium hydroxide in a water-ether mixture into 3,5-O-benzylidene-1-deoxy-~-erythro-2-pentulose in 55% yield. Hydrolysis to the free pentulose (20) proceeded in 73% yield in aqueous acetic acid. This product was obtained as a syrup with a characteristic absorption band at 1705 cm-' as a film. Thus, there is a fair proportion of the open-chain ketone under these conditions, as with the D-threo e ~ i m e r . ~ ~
IV. A PENTULOSE OR PENTULOSE DERIVATIVE AS THE PRECURSOROF THE FIVE-CARBON CHAIN OF THE THIAZOLE OF THIAMINE IN YEASTS It was shown early on that glycine supplied the C-2-N unit in the thiazole for the yeast Saccharomyces ~ e r e v i s i a eThe . ~ ~ incorporation of C-2 of glycine did
SUGARS, NLJCLEOTIDES, THIAMINE BIOSYNTHESIS
289
not proceed via the pool of one-carbon units because from the other known sources of these units, such as C-3 of serine, or formate, no incorporation was detected.47 These observations were fully confirmed by more-rigorous techniques!8 Thus, a difference between this yeast and enterobacteria was already observed. Another difference was found in the biosynthesis of the five-carbon hai in.^,^ Although (Me-*H,)pyruvate was a precursor in E . cofi (see subsection 111.2), thiazole from the yeast cells grown on glucose in the presence of [3‘‘C]pyruvate or [U-I4C]lactate (a precursor of [U-14C]pyruvate)was only marginally labeled. Consequently, the authors had to rely on the study of more-genera1 precursors, such as glucose. However, glucose with reasonable radioactivity could no longer be used as a general carbon source, for this would have led to an unacceptably low specific activity in the thiazole isolated. It was found that ethanol, after a 24-hour lag period, served as a carbon source for S. cerevisiue, and it was utilized for growth in these studies. For a complete understanding of the results, it is advisable to recall the two main paths of glucose metabolism in microorganisms. In the so-called oxidative pathway glucose is converted, after phosphorylation, into D-erythro-pentulose 5 phosphate (44), as summarized in Scheme 20. Carbon C-1 of glucose is eliminated in the process, and carbon atoms C-2, C-3, C-4, C-5, and C-6 of glucose are the respective precursors of carbon atoms C-1, C-2, C-3, C-4, and C-5 of the pentulose phosphate. In the “non-oxidative pathway” (Scheme 21), glucose is phosphorylated and isomerized to D-fructose 6-phosphate, which is split in the well-known manner into two three-carbon fragments. The transfer, catalyzed by the enzyme transketolase, of a two-carbon unit from D-fructose 6-phosphate to D-glyceraldehyde 3-phosphate produces D-threo-pentulose 5-phosphate (45). Then, carbon atoms 1, 2, 4, 5, and 6 of glucose are the respective precursors of carbon atoms 1,2,3,4, and 5 of the pentulose phosphate 45. Because the carbon atoms of pentose phosphate recycle into hexose phosphate, the non-oxidative pathway could eventually lead to a less clear-cut pattern of incorporation. “This eventuality did not arise.’@Phosphates 44 and 45 are interconvertible in cells.
(i””
I
I
HOCH
-
I
HO CH
I
HCOH
HCOH
H COH
H COH
I
I
I
HCOH
HCOH
HCOH
I
CH20P03H2
CHPOPO3HZ
I
-
I
co HCOH I H COH
I
CHPOH
-
I
co I
HCOH I H COH
CH20POSH2
I
CHpOPOsH2 44
SCHEME 20. -The
“oxidative pathway” for D-glUCOSe catabolism.
SERGE DAVID AND BERNARD ESTRAMAREIX
290
El HO &H
I
'-
HCOH
I
'I
7H20P03H2 co
-
co I
HO CH
I
HCOH
I
- It
e-
CHO
H COH
H COH
1
I
CHpOP03Hp
CHpOH I
7H20p03H2
'\,
CHpOP03H2
I
H COH
I
CH20P03H2
~
HO CH I HCOH
I
45 SCHEME 2 1 .-The "non-oxidative pathway" for o-glucose catabolism.
If the pentose phosphates (44 or 45) are indeed the precursors of the five-carbon chain of thiazole, it seems fairly obvious that the carbonyl group will participate in building the heterocyclic ring. Thus, carbon atoms C-1, C-2, and C-5 of the sugar would be the respective precursors of the methyl, C-2, and C-8 carbon atoms of the thiamine thiazole. Under these conditions, if the oxidative pathway is operating, D-[1-14C]glucosewould produce unlabeled thiazole, D-[6-14c]glucose, thiazole labeled on C-8, and ~-[2-'~C]glucose thiazole labeled on the methyl carbon atom. On the other hand, in the non-oxidative pathway, these three glucose precursors would produce thiazole molecules labeled respectively on the methyl, C-8, and C-4 carbon atoms. Actually, activity from D-[ l-14C]glucose is located almost entirely on the methyl group. With ~-[6-'~C]glucose as precursor, 80% of the label was located at C-7 of the thiazole. However, in a study with D-[2-'4C]glUCOSe, half of the radioactivity was found on the methyl group, and the other half at C-4. The distribution of activity between C-4 and C-8 serves as a measure of the relative contributions of the two pathways, which appear to be approximately equal under the conditions of the experiment.* The distribution of activity in the thiazole was elucidated with the help of the degra-
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
29 1
dation described in Scheme 6. The intervention of a non-oxidative pathway is not surprising in the yeast S. cerevisiae, an organism essentially developed during thousands of years for fermentation purposes. The respective contributions of the oxidative and non-oxidative pathways vary, according to the yeast strains and the incubation conditions. The conclusion cannot be confirmed by experiments using labeled ribose because exogenous ribose is not taken up by S. cerevisiae. A more-recent study was conducted on cultures of another yeast, Candida ~ t i i i sIt. ~has ~ been known for some time that the ribose of the FWA in this yeast is only formed by the oxidative p a t h ~ a y . ~Again, ' labeled glucose molecules were used as a precursor, and the main carbon source provided to the culture was glycerol, to avoid excessive dilution of label. Thiamine was extracted from the cells; the thiazole was separated and degraded following the method of Scheme 5 to localize the radioactive carbon atoms. Likewise, the specific activity of the ribose moiety of adenosine 3'-phosphate from the cellular RNA hydrolyzate was determined. The dilution rates of the specific activity into the ribose, with D-[U''C]glucose, ~-[2-'~C]glucose, and ~-[6-'~C]glucose,respectively, were about tenfold for each. The figures were, respectively, 8.2, 9.9, and 9.65 for thiazole. As expected, the label from ~-[6-'~C]glucose was found exclusively on C-8. The degradation of the thiazole labeled with ~-[2-'~C]glucose as precursor indicated labeling at C-4 and the methyl carbon atom, and, from the reported figures, the reviewers calculate the ratio of non-oxidative/oxidative as 1/3. This is difficult to reconcile with the 138-fold dilution of label observed with D-[ 1-'4C]glucose, which seems to indicate a much smaller contribution of the non-oxidative pathway, as expected with this organism. A direct localization of labeled atoms on the D-ribose molecule would have been useful in this context. In these experiments, the culture medium contained cold (unlabeled) glycine. Because no label was observed at C-2 upon growth in the presence of D-[U''C]glucose confirmed that this carbon originated from glycine. Scheme 22 summarizes the present stage of our knowledge of the synthesis of thiazole in yeasts. The existence of two biosynthetic pathways for thiazole is commented on in Sections VII and VIII. CHO
I
HCOH
-
I
HOCH
I
HCOH
I H COH
I CHzOH SCHEME 22.-Proposal yeast.
-
,H) " -
CHOH CHZOPOSH,
H2C'
H\
YH
N
H A . H'
'C02H
CH20P03H2
for the formation of the thiamine thiazole from a pentulose and glycine in
292
SERGE DAVID AND BERNARD ESTRAMAREIX
v. 5-AMINO- 1-(P-D-RIBOFLJRANOSYL)IMIDAZOLE5 '-PHOSPHATE, THE PRECURSOR OF PYRAMINE IN
ENTEROBACTERIA
1. Derepression of the Synthesis of Thiamine In a growing culture of a mutant of the enterobacterium Salmonella typhimurium auxotroph for thiamine, the concentration of thiamine in the cells is strictly controlled, in the vicinity of 30 ng per mg of dried cells, and there is no excretion of thiamine into the medium. The synthesis of thiamine is negligible in resting cells. This regulation is because thiamine, above a certain concentration, induces a repression of its own synthesis, which comes into effect as soon as the cell content reaches 40 ng per mg of dried cells. Thiamine then represses production of the enzymes involved in its synthesis. On the other hand, it was found that the thiamine content of cells can be kept minimal (20 ng) by culture in the presence of adenosine. Under such conditions, there is derepression of the enzymes involved in thiamine ~ynthesis.~' Starting from these observations, Newell and Tucker designed a most useful system for study of the biosynthesis of thiamine. Culture in the presence of adenosine provided cells containing about 15-20 ng of thiamine per mg (of dried cells). Then, the cells were removed by centrifugation and suspended in a medium devoid of adenosine, and not allowing growth. These cells immediately began to synthesize significant quantities of thiamine, up to five times the normal content. This phenomenon of derepression is not limited to incubation in the presence of adenosine, but can be observed whenever the concentration of thiamine is kept artificially low during growth: thus, a mutant incapable of making thiazole can only grow in the presence of external thiamine. If only limiting quantities are supplied, the synthesis of pyramine is derepressed and it accumulates in the medium. It was found later that the actual repressor is thiamine d i p h ~ s p h a t eThe . ~ ~ elaboration of a technique for the preparation of cells derepressed for the synthesis of thiamine was a major breakthrough in the field because it allowed the observation of the synthesis of relatively large quantities of thiamine in resting cells. Studies with labeled precursors were made easier, and the use of a mutant auxotrophic for a given compound indicated whether or not this compound was involved in thiamine biosynthe~is.~~ From this observation of the inhibition by adenosine, and other observations, Newell and Tucker suspected the existence of a common synthetic pathway for adenosine and thiamine, and proved (with the help of a collection of mutants) that the bifurcation occurred after the 5-amino- 1-( P-D-ribofuranosy1)imidazole 5'-phosphate (46) step (Scheme 23). Finally, they found that 5-amino- 1-(P-D-ribofuranosy1)imidazole (47), labeled with I4C in the imidazole ring, was incorporated into pyramine without significant loss of molar radioactivity by a mutant that is able to use this nucleoside (presumably after pho~phorylation).~~~~~
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
293
SCHEME 23.-Some important steps in the biosynthesis of adenosine 5'-phosphate, and the branching of the sequence at the AIR level, leading ultimately to pyramine, in S. ryphimurium cells.
A more-detailed account of derepression phenomena, regulation of thiamine biosynthesis, and mutant investigations can be found elsewhere.'
2. From Imidazole to Pyrimidine: The Ring Expansion Henceforward, the chapter focuses on problems closely connected with the chemistry of ribonucleotide 46 and ribonucleoside 47. The official numbering of the atoms in these molecules is recalled in formulas 46, 47. The common abbreviations, AIR and AIRS respectively, are used for the ribotide and the riboside.
46
R=POSHZ
47 R = H
294
SERGE DAVID AND BERNARD ESTRAMAREIX
Although the foregoing conversion indicates that all of the carbon atoms of the base of AIRS participate in the formation of pyramine, this pyrimidine contains three more carbon atoms not accounted for. To understand what happens, it is necessary to elucidate details of the imidazole ring-enlargement. The path of each individual carbon atom can be determined by using samples of the riboside labeled at specific places. A chemical synthesis of 47 has been reported55and was utilized later on. However, for the present purpose, it is simpler to take advantage of the fact that the biosynthesis of the imidazole ring of AIR is well established. Resting cells of suitable mutants were incubated with radioactive precursors, pyramine was extracted from the medium, and the site of labeling was elucidated with the help of the degradation described in Scheme 7. The organisms utilized were two S. typhimurium mutants, thi-28n and thi-28/T.Gly, which both need thiamine and tryptophan for growth; the second needs also glycine. It is well known that the carbon atom of formate, carbon atom C-1 of glycine, and carbon atom C-2 of glycine are the respective precursors of C-2, C-5, and C-4 of the imidazole ring in AIR. [14C]Formate was incorporated at C-2 of pyramine by resting cells of mutant thi-28n.gly. With [ l-14C]glycine as precursor, the label was found on carbon C-4 of pyramine. Incubation with [2-14C]glycineproduced a pyramine labeled on C-6. The conclusion is that C-2, C-4, and C-5 of imidazole are the precursors of C-2, C-6, and C-4 of pyramine.5g56Thus, the ring expansion involves the breaking of the double bond between carbon 4 and 5 of imidazole, as shown in Scheme 24. This Scheme also depicts the correspondence between the nitrogen atoms of the 5-aminoimidazole base and those of pyramine, in anticipation of results obtained in the next subsection, and obtained with a different technique.
SCHEME 24.-Correspondence between the carbon atoms of AIR and those of pyramine, and the mode of opening of the imidazole ring in the ring expansion in the synthesis of pyramine.
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
295
Further work demonstrated that the three missing atoms came from the ribose part of AIR. For this, it was necessary to prepare samples of AIRs specifically labeled on the ribose part. The methods are described in the following section.
3. Preparation of Specifically Labeled Samples of 5-Amino-l(P-D-ribofuranosyl)irnidazole(AIRs)
a. Chemical Methods.-Scheme 25 summarizes the reported chemical synthesis of AIRs. Treatment of D-ribose with saturated methanolic ammonia produced D-nbopyranosylamine (48) in greater than 90% yield.57 This glycosylamine, when stirred with 2,2-dimethoxypropane and p-toluenesulfonic acid, produced the sulfonate salt of D-nbofuranosylamine derivative 49. Although 48 and 49 are crystalline compounds, and thus most probably homogeneous, their anomeric configurations in the solid state have not been ascertained. From the proton NMR spectra, compound 49 appears to exist in CDCl, solution as the pure p anomer, but as an a$ mixture in dimethyl sulfoxide. Reaction of 49 with the methoxymethylene derivative of an alkylmethylene cyanoacetate 50 produced a mixture of the protected p nucleoside (51), together with its a anomer. Chromatography on a column of silica gel followed by crystallization finally produced crystalline 51. Acidic deacetalation produced 52, 5-Amino- ~-(P-Dribofuranosy1)imidazole itself is an unstable molecule. An aqueous solution could be prepared from 52 in two steps. Hydrolysis of the ester function by 0.25 M NaOH at 80°C, followed by acidification to pH 4.7 produced acid 53, which was smoothly decarboxylated in situ at 50°C under a stream of nitrogen. Chromatography on Dowex-50 X8 (NH4+) then produced an aqueous solution of 5-amino- 1-(P-D-ribofuranosyl)imidazole, which was used at once in metabolic studies?* The difficulties inherent in the estimation of the riboside in solution are dealt with at the end of this section. Despite some uncertainties, there is no doubt, from experiments in the laboratory of the authors of this chapter, that a considerable loss of product reacting positive in the Bratton-Marshall assay (see later) was observed on freeze-drying. Scheme 26, which recalls the classic reactions involved in the synthesis of 50 from small, common molecules, will help in following the methods used for labeling the imidazole ring of AIRs. Nitrosation with ("N)NaNO, allowed the preparation of AIRs labeled on N-3. When methyl cyanoacetate was prepared with (''N)KCN, AIRs labeled on the amino nitrogen were obtained. With the same synthetic sequence, labeled ribose molecules produced AIRs labeled on the ribose moiety. From D-erythrose and (I3C)NaCN, the FischerKiliani synthesis, as modernized by Serianni et al?' produced D-( 1-13C)ribose and D-( I -I3C)arabinose.The labeled arabinose was transformed into D-(2-13C)nbose in the presence of dioxobis(2,4-pentanedionato)-O-O'-molybdenum(VI)in
SERGE DAVID AND BERNARD ESTRAMAREIX
296
48
49
CN 49
I
+ MeOCH=N- H
7
-
C02R
50
{xco2R
fl
NH2
OR' OR' 51
R', R'= CMe2
52
R'. R' = H
OH OH 53
SCHEME25.-Chemical
synthesis of AIRS.
N,N-dimethylformamide.60 The sugars were isolated on a column of Dowex-50 X8 in the calcium form.61Both D-(l-13C)-and ~-(2-'~C)-ribose are now commercially available. These sugars allowed the preparation of samples of AIRS labeled with I3C either on C-1' or on C-2'. In conclusion, four ribonucleosides are now available practically fully labeled at a single position.58
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
I
I
CH2Cl
CHpCN
/C02CH3 HO-N=C \ 'CN
SCHEME 26.-The
291
Na2S204
/Co2CH3 NH2-Y 'CN
50 preparation of small molecules intermediate in the chemical synthesis of AIRs.
b. Biochemical Methods.-Specifically labeled samples of AIRS can also be prepared biosynthetically with the help of strain W-1 1 of E . coli. This organism excretes AIRs in the medium, when cultured under certain conditions, with glucose as the main carbon source.62From a culture in the presence of D-(UI3C)glucose,an AIRs evenly labeled with I3C was obtained. Incubation in the presence of inactive D-glucose and ~-[U-'~C]riboseproduced AIRs where 84-90% of the radioactivity was located on the ribose part.63This labeling was expected a priori because it is known that D-ribose is poorly metabolized by E . coli in the presence of glucose, its carbon atoms being mainly incorporated into direct metabolites of D-ribose phosphate. In the same way, from ~-[l-'~C]ribose, a sample of AIRs with 91% of its radioactivity on C-1' was prepared.64In the last preparation of this series, the incubation medium contained [ 1-I4C]lactate. This preparation produced a sample of AIRs labeled practically only at C-l', C-2' and C-3' in the ribose part and at C-5 of the imidazole, in the relative ratiosH 1, 1, 3, 3. As is well known, ~-[l-'~C]lactate is metabolized into [ 1-'4C]pyruvic acid, D-[ 1-'4C]glyceraldehyde 3-phosphate, and thence into the phosphates of hexoses labeled at C-3 and C.4. The oxidative pathway converts this labeled glucose phosphate into ribose phosphate labeled on C-2 and C-3. On the other hand, the action of transaldolase and transketolase in the non-oxidative pathway results in the introduction of label at positions 1 and 3. Thus, in the two known routes to ribose phosphate, C-3 originates from a labeled carbon atom of
SERGE DAVID AND BERNARD ESTRAMAREIX
298
lactate and should be labeled at the same level as C-1 of triose phosphate. As for C-5 of imidazole, its precursor is C- 1 of glycine, and therefore, C - 1 of D-glyceraldehyde 3-phosphate, and it should also be labeled at the highest level, as at C-3’. Scheme 27 shows the degradation methods utilized in this context to localize the activity in each carbon atom of D-ribose, after hydrolysis of the riboside.
Q
D-ribose
Q / \
- ““YN ””YN+ HCOH
CHO
HCOH
HC02H
HCOH
HC02H
I
+ + CH20
I
I
CH20H
D-Ribose
-
CH20CPh3 1 HCOH Ribitol-
CH20CPh3
I
CHO
I
+ +
I
CHO
I
H COH H COH COCPha
-t
H C02H
-
2
CH20H
I
COCPh3
I
COCPh3 SCHEME27.-A bon atom.
degradation of D-ribose,which allows the localization of radioactivity in each car-
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
299
For quantitative work, it is necessary to estimate the concentration of 5amino- 1 -(P-D4bofuranosyl)imidazole in aqueous solution. It seems that the only available method is the Bratton-Marshall assay, which was originally developed for the estimation of arylamines in biological fluids. The principle of the method is the spectrometric estimation of a salmon-pink colored dyestuff obtained by diazotation in situ, followed by coupling with N-( 1-naphthy1)ethylenediamine.6sThe only remaining problem then is to know the molar extinction of this dye because pure samples of AIRs are not available. A value of 16 800 at 520 nM was obtained for the dyes prepared from a model compound, 5-amino1-cyclohexylimidazole-4-carboxylicacid (54), which is crystalline. A comparable molar extinction can be expected for the dye prepared from imidazole 55, if the carboxyl group does not exert too much influence on the chromophore. Actually, its influence is perceptible even with the naked eye, the dyestuff prepared from 53 having a somewhat different, wine-red color, with h,,,>520 nM. The molar extinction for 55 is 17400 at 500 nM. When the decarboxylatjon of 54 was conducted under mild acidic conditions (pH 4.8,50"C, 1 hour), estimation of 5-aminoimidazole 55 by the Bratton-Marshall method led to the conclusion that the reaction was almost quantitative.66Similar conditions for the final decarboxylation were adopted in the preparation of samples of AIRs labeled with stable isotopes.58
46 R = H 56 R=C02H
54 R=CO?H 55 R = H
57
SERGE DAVID AND BERNARD ESTRAMAREIX
300
c,o\l I
(HO),PO-OEH,
Q N
NH2
(HO),PO-O-CH, -i"NH2
$XH*
(HO),PO-O-CH,
\ I c-c I
I
OH OH
HO HO
OH OH
1',2'.3.4',5'-'4Cs
3-"N
arnino-"N
SCHEME 28.-The seven specifically labeled AIRS prepared. The sites of labeling are indicated with the labeled atoms in bold type.
However, more-rigorous treatment (5% acetic acid, 100°C, 17 hours) opened the imidazole ring and produced N'-cyclohexyl-a-formylaminoacetamidine(57), characterized as the crystalline picrate. Amidine 57 produced no dye in the Bratton-Marshall assay. The same behavior can be expected from AIR (46), although the product of hydrolytic ring-opening was not actually isolated. On the other hand, it was observed that a solution of AIRS (0.2 mM in 0.01-M ammonium hydroxide) prepared by biosynthesis, when stored at 4°C did not change appreciably within a day. A decrease in the concentration of AIRS of about 30% occurred within a month. The six specifically labeled AIRs prepared by the foregoing methods are shown in Scheme 28. 4. Biosynthetic Studies Thiamine was biosynthesized by resting cells of S. typhimurium strain thi 10/r-ath-38P, which can synthesize thiamine from exogenous glucose, AIRs, and t h i a ~ o l eDerepression .~~ was achieved by conventional means. The organism was cultivated in the presence of a suboptimal amount of thiamine (20 nM), the washed cells were resuspended in a minimal medium containing glucose (10 mM), thiazole (1 -2 mM), and labeled AIRs (10 pM). During the incubation (1.5 hours; 37"C), the level of thiamine diphosphate in the cells had risen from about 0.04 to 0.5 nmol/mg. In work with molecules labeled with stable isotopes, thiamine was extracted and cleaved by ethanethiol to 4-amino-5-(ethyl-
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
301
thiomethyl)-2-methylpyrimidine(Scheme 9), which was examined by mass spectrometry. In the experiments with radioactive isotopes, thiamine diphosphate was diluted with inactive carrier, and cleaved by ethanethiol to the same pyrimidine. This was converted in two steps into 4-hydroxy-2,5-dimethylpyrimidine, which was degraded according to Scheme 7. The experiments with (U-I3C)AIRs showed that this nucleoside supplied all of the carbon atoms of pyramine. Because out of 6 carbon atoms of pyramine, only three may come from the imidazole part of AIRs, it can be concluded that the three other carbon atoms come from the ribose part of this nucleoside. In complete agreement with these results, radioactivity from AIRs, labeled mainly with 14C in its ribose part, was found to incorporate into the three carbon atoms of pyramine, the origin of which was, at the time, unknown. Owing to the minute amount of AIRs supplied (as compared with that of glucose) in both experiments, the incorporation of label from AIRs after metabolic degradation is ruled out. Further experiments with labeled precursors were necessary to shed a little more light on this puzzling observation. Pyramine, biosynthesized from AIRs labeled with 14Con c-1’on the ribose part, exhibited only marginal radioactivity. This result rules out C-1 ‘ of ribose in AIRs as a precursor of pyramine. This conclusion was confirmed with a precursor labeled at the C-1’ position with the stable ‘jC isotope. The mass spectrum of the ethylthio derivative of pyramine was identical with that of an unlabeled sample (Scheme 9). On the other hand, the fragmentation of pyramine obtained from (2’-I3C)AIRs indicated clearly that C-2’, in the ribose part, was the precursor of carbon C-7 of the methyl on C-2 of the pyrimidine ring (Scheme 29). This result was confirmed by an experiment with a sample of AIRs labeled with I4C on C-1’. C-2’. C-3’, on the ribose, and C-5 on the imidazole, with an approximate distribution of 1, 1, 3, 3. This precursor produced pyramine with the methyl group almost as radioactive as C-1’or C-2‘, and much less than C-3’ of AIRs. Because of the incorporation of C-5 of imidazole into C-4 of pyramine, and the comparable activities of C-3’ and C-5 in the precursor AIRs, the specific activity of pyramine
SCHEME 29.-Carbon atom C-2’ of AIRs is the precursor of the methy1 of pyramine. Thc lahdctl atoms are printed in bold type.
SERGE DAVID AND BERNARD ESTRAMAREIX
302
I
‘ ’
H2N H H-& !?“ --C
\
HO-2-Y H
L
N
/,
OH OH SCHEME 30.-Correspondence between ribose and pyramine carbon atoms in the biosynthesis by S. typhimurium.
was, as expected, close to that of C-3’ of the ribose. Furthermore, C-5 and C-8 of pyramine were not labeled in this experiment, and, because it is known that these carbon atoms come from ribose, they can only come from the unlabeled atoms of the ribose part of AIRs, that is, from C-4’ and C-5’. Finally, the experiments with AIRs, specifically labeled either on N-3 or on the amino nitrogen, proved that N-3 of the imidazole ring is the precursor of N-1 of pyramine, and that the amino nitrogen atom of the imidazole becomes the amino nitrogen atom of pyramine. The mode of incorporation of the carbon atoms is depicted in Scheme 30, and that of the nitrogen atoms in Scheme 3 1. The connection now clearly established between the heavy atoms of AIRs and those of pyramine shows that the conversion involves the breaking of five bonds: between C-4 and C-5, N-1 and C-1’, C-1’ and C-2‘, C-2’ and C-3’, and C-3’ and C-4’, while three new bonds are created, C-4’ to C-4, C-4’ to C-5, and C-2’ to
c-2. The following very important observations must be accounted for in any mechanistic proposal: cells were incubated with a mixture of (2’-l3C)A1Rs and (3-’’N)AIRs. A mass-spectrometric analysis of the product of biosynthesis showed that this was a mixture of two pyrimidines, one labeled at the methyl carbon atom, the other at N- 1: no pyrimidine twice labeled or unlabeled was observed; these latter would have arisen from recombination of fragments carrying C-2’ or N-3. The conclusion is that the fragments containing C-2’ and N-3, orig-
OH OH
H/
SCHEME 3 1 .-Correspondence between the nitrogen atoms of AIRs and those of pyramine in S . lyphimurium.
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
303
CHpCOpH 58
SCHEME 32.-Decarboxylation of 4-amino-2-carboxymethyl-5-hydroxymethyl-pyrimidine.
inating from base and sugar, remain mutually bound in some unspecified manner during the building of the pyrimidine. Clearly, we are in the presence of a new, unprecedented transformation in ribonucleotide chemistry.’* It has been shown already that C-2’ of ribose is the precursor of the methyl group, and C- 1’ is eliminated in the biosynthesis. The following observation can be pertinent to the point. Pyrimidine (58) is very unstable and quickly decarboxylates in aqueous solution at room temperature to give pyramine (Scheme 32).67Thus, if a C-l’-C-2’ fragment of the ribose part of AIRS became attached by C-2’ to C-2 of a pyrimidine, oxidation of C-1’ to produce a carboxylic acid function could result in its smooth elimination. VI. PYRAMINE SYNTHESIS IN YEASTS Much less is known about the participation of sugars in the biosynthesis of pyramine in yeasts, and although it has been proven that sugars can provide some carbon atoms, the exact nature of the more advanced intermediates of sugar origin is not yet clear. Some features of the biosynthesis in S. cerevisiae are summarized in Scheme 33. Two ‘’N atoms from DL-( 1,3-”N2)histidine were incorporated into the N-3 and amino nitrogen atoms of pyramine. The nitrogen atom of (”N)aspartate, a known precursor of N-1 of histidine, was incorporated into pyramine without di l~ti on.6*-~~ It was also found that N-1 and C-2 of pyramine came respectively from N-1 and C-2 of pyrido~ol.~’-’~ The three carbon atoms of pyramine not accounted for are C-5, C-6, and C-8. Again the problem was examined with the yeast C . utitis, which makes ribose derivatives by the oxidative pathway. In these experiments, glycerol was the main carbon source. The label of ~-[l-’~C]glucose was only incorporated at a very high dilution. Carbon C-2 of ~-[2-~~C]glucose was incorporated with the same dilution in pyramine (about 6) as in the ribose of adenylic acid. Degradation of the labeled pyramine showed that the radioactivity was localized on C-6. With ~-[U-’~C]glucose the dilution was 5.4, admitting the incorporation of three carbon atoms, and was the same as in ribose.72Thus, it is possible that a threecarbon fragment of ribose, C-1 -C-2-C-3, is the precursor of the C-6-C-5-C-8 sequence of pyramine, as shown in Scheme 34. However, an unexpected fragmentation of the pentose molecule, as in the enterobacteria, cannot be ruled out.
SERGE DAVID AND BERNARD ESTRAMAREIX
304
COpH
I
H2NCH
C02H CO2H
I
I I
H2NCH
HCNH2
I
bO\QH
N-
I
1
SCHEME 33. -The yeast.
CHpOH
CH2
CH2
1
participation of L-histidine and pyridoxol to the biosynthesis of pyramine in
SCHEME34.-The participation of D-glUCOSe to the biosynthesis of pyramine by C. ufilis
SUGARS, NUCLEOTIDES, THIAMINE BIOSYNTHESIS
305
VII. THE DISTRIBUTION OF THE FOUR BIOSYNTHETIC ROUTES IN NATURE 1. Biosynthesis of Pyramine a. Cells for Which the AIRS Pathway is Established or Possible.-It would be useful to be able to determine which mode of synthesis is operating without resorting to the complicated experiments described here. When an organism utilizes the AIR pathway, the following observations can be anticipated: (a) inhibition by adenine or adenosine, (6)existence of adth- mutants, which require both adenine and thiamine for their growth, and (c) typical incorporation of formate at C-2 of pyramine, and glycine at C-4 and C-6 of pyramine, a fact readily explained by the mode of introduction of these precursors molecule in the skeleton of imidazole. In the light of these criteria, organisms other than S. typhimurium, are now examined. Escherichia coli: Adenine and adenosine are inhibit~ry'~ and the synthesis of thiamine can be derepressed by culture in their p r e ~ e n c e . 'adth~ , ~ ~Mutants are known.76[I4C]Formateincorporates at C-2 of pyramine without dilution of molar activity. Glycine labeled with stable isotopes was fed to E . coli and the pyramine was analyzed by mass spectrometry. The two carbon atoms of glycine separated during the biosynthesis. The carboxyl was foundI2 at C-4, and the C-N fragment was the precursor of C-6-N-1. In conclusion, it is beyond doubt that pyramine synthesis follows the AIR pathway in E. coli. Enterobacterbacter aerogenes: adth-Mutants have been isolatedJ7 and adenine inhibits the synthesis of thiarni11e.7~~~~ [I4C]Formateincorporates at C-2 of pyramine." Micrococcus denitrijicans: Adenosine derepresses the enzymes involved in the coupling of pyramine with t h i a ~ o l e . ~ ~ Pseudomonas putida, Bacillus subtilis: [ I4C]Formate incorporates at C-2 of pyramine.78 Spinach chloroplasts: There is some evidence that pyramine originates from AIR." b. Cells for Which the Histidine Pyridoxol Pathway is Established or Possible.-This pathway has been established for two yeasts, S. cerevisiae and C . utilis, but it was also found that [14C]formateis the precursor of C-4 of pyramine in Mucor racernosus,Aspergillus nidulans, and Neurospora cra~sa.~' c. Evidence for a Eukaryote-Prokaryote Dichotomy.-Strictly speaking, incorporation of formate at C-2 only means that the histidine pathway is not operating, and incorporation at C-4 only means that the AIR pathway is not operating. However, as long as a third route to pyramine remains undiscovered, this kind of evidence deserves consideration. The classification of the organisms mentioned in sections VII.1, a and VII.1 b, strongly suggests that the AIR
306
SERGE DAVID AND BERNARD ESTRAMAREIX
pathway is characteristic of prokaryotes and the histidine pathway is characteristic of eukaryotes. It might be significant that the more primitive organisms utilize a ribonucleotide, surely a primitive molecule, as precursor.
2. Biosynthesis of Thiazole The tyrosine-deoxypentulose pathway is firmly established for S. typhimurium, E . coli, and spinach chloroplasts. The glycine-pentulose pathway was discovered with the yeasts S. cerevisiae and C . utilis. There are similarities between these two modes of biosynthesis. Carbon C-2 and nitrogen in both cases arise from an amino acid, either tyrosine or glycine, and all of the other carbon atoms are lost. It is not excluded that both paths converge toward the same precursor of thiazole-especially if it is considered likely that the aromatic residue of tyrosine is probably eliminated before the carboxyl group. Also, in both instances, the rest of the thiazole molecule is built from a five-carbon sugar. Again, it can be speculated that the tyrosine-deoxypentulose route is characteristic of prokaryotes and the glycine-pentulose route is characteristic of eukaryotes. The question would naturally arise as to whether there is a genetic link between the biosyntheses of pyramine and thiazole in the sense that all organisms making pyramine by the AIR route will make thiazole from tyrosine. In this respect, attention is drawn to a report*' that the prokaryote B . subtilis incorporates nitrogen from ['5N]glycine, into its thiazole, an observation appearing to indicate that it makes it in a manner similar to the yeasts. VIII. CONCLUSION Although the gross features of the biosyntheses of thiazole and pyramine have been elucidated, nothing is known about the nature and order of the individual steps. The relevant enzymes have not yet been found, although it might be hoped that the knowledge accumulated on the precursors and the paths of atoms will help in this respect. An attempt has been made recently to find the genes involved in the biosynthesis of thiazole.82 Because sugars are involved in most of the mechanisms established for the synthesis of these heterocycles, the development of carbohydrate chemistry has been most helpful in these researches -especially for the preparation of specifically labeled molecules. Conversely, the contribution of these efforts to carbohydrate chemistry and biochemistry has shown the involvement in biosynthesis of 1-deoxy-D-threo-pentulose-scarcely before recognized and considered a rare sugar-and of fully functionalized pentuloses of still unknown configuration (or their phosphates). Finally, evidence has been found in prokaryotes for a most extraordinary transformation of 5-amino-l-(~-~-ribofuranosyl)imidazole 5'-phosphate into a pyrimidine. Surely, this transfornation should be explained in terms
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of organic chemistry, and it indicates that there are still unexplored properties in the organic chemistry of ribonucleotides. It might be significant that prokaryotes, the more primitive organisms, utilize a ribonucleotide precursor, surely a primitive molecule. Indeed, it had been suggested that primitive life developed in a so-called ARN universe, which has bequeathed to the contemporary world, among other things, the nucleotide coenz y m e ~ . *Pyramine ~ could be added to this legacy, as the product of a “fossil” mode of synthesis. On the other hand, it might also be significant that the biosynthesis in spinach chloroplasts follows the prokaryotic route, utilizing 1deoxy-D-rhreo-pentulose as precursor. There is also some evidence that pyramine originates from AIRS. This is interesting because some evolutionary hypotheses have been put forward for the origin of the chloroplasts in the eukaryotic cell: either the chloroplasts descended from free-living prokaryotes, which entered into an endosymbiotic relation with a host cell having a nuclear genome, or the progenitor genome segregated, becoming physically compartmentalized within a single cell. “It does appear that the endosymbiot hypothesis is the more plausible. . . A theory proposes that chloroplasts derived from an ancestral photosynthetic prokaryote related to cyanobacteria is supported in part by comparison between chloroplasts and cyanobacterial operons coding for ribosomal ARN’s.’~~ The discovery that chloroplasts make thiamine, as do bacteria, also supports the endosymbiot hypothesis. REFERENCES 1. B. Estramareix and S. David, N e w J . Chem., 20 (1996) 607-629. 2. R. R. Williams, R. E. Waterman, J. C. Keresztezy, and E. R. Buchman, J . Am. Chem. Soc.. 57 (1935) 536-537. 3. G. E. Bonvicino and D. J. Hennessy, J . Org. Chem., 24 (1959) 451 -454. 4. S. David, B. Estramareix and H. Hirshfeld, Biochim. Biophys.Actu, 148 (1967) 11-21, 5. B. Estramareix and M. Lesieur, Biochim. Biophys. Actu, 192 (1969) 375-377. 6. P. E. Linnett and J. Walker, J . Chem. Sue. C, (1967) 796-799. 7. R. L. White and 1. D. Spenser,J. Am. Chem. Soc.. 101 (1979) 5102-5104. 8. R. L. White and I. D. Spenser, J . Am. Chem. Soc.. 104 (1982) 4934-4943. 9. S. David and H. Hirshfeld, Bull. Sue. Chim. France, (1966) 527-529. 10. G . Grue-Soerensen, R. L. White, and 1. D. Spenser, J . Am. Chem. Soc., 108 (1986) 146- 158. 1 1. R. H. White and F. B. Rudolph, Biochirn. Biophys. Acfu,542 (1978) 340-342. 12. R. H. White and F. B. Rudolph, Biochemistry, I8 (1979) 2632-2636. 13. B. Estramareix and M. ThCrisod, Biochim. Biophys. Actu. 273 (1972) 275-282. 14. R. H. White, Biochim. Biuphys. A m , 583 (1979) 55-62. 15. E. Bellion, D. N. Kirkley, and J. R. Faust, Biochim. Biophys. Actu, 437 (1976) 229-237. 16. B. Estramareix, D. Gaudy, and M. ThBrisod, Biochimie (Paris), 59 (1977), 857-859. 17. E. Bellion and D. H. Kirkley, Biochim. Biophys. Actu, 497 (1977) 323-328. 18. E. DeMoll and W. Shive, Biochim. Biophys. Res. Commun., 132 (1985) 217-222. 19. K. Tazuya, K. Yamada, K. Nakamura, and H. Kumaoka, Biochim. Biophys. Acta, 924 (1987) 2 10-2 15.
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20. M. Thbrisod, J. C. Fischer, and B. Estramareix, Biochim. Biophys. Res. Commun., 98 (1981) 374-379. 21. S. David, B. Estramareix, J. C. Fischer, and M. ThCrisod, J . Am. Chem. Sac. 103 (1981) 7341 -7342. 22. S. David, B. Estramareix, J. C. Fischer, and M. ThCrisod, J . Chem. Soc. ferkin Trans. I , (1982) 2131-2137. 23. J. H. Julliard and R. Douce, froc. Natl. Acad. Sci. USA, 88 (1991) 2042-2045. 24. L. Slechta and E. Johnson,J. Antibiotics, 29 (1976) 685-687. 25. H. Hoeksema and L. Baczynskeyj, J. Antibiotics. 29 (1976) 688-691. 26. A. Yokota and K. Sasajima, Agric. B i d . Chem.,48 (1984) 149- 158. 27. I. A. Kennedy, T. Hemscheidt, J. F. Britten, and I. D. Spenser, Can. J . Chem., 73 (1995) 1329- 1337. 28. M. L. Wolfrorn and R. B. Bennett, J. Org. Chem., 30 (1965) 458-462. 29. A. Ishizu, K. Yoshida, and N. Yamazaki, Curhohydr. Res., 23 (1972) 23-29. 30. A. D. Backstrom, A. S. McMordie, and T. P. Begley, J . Carbohydr. Chem.. 14 (1995) 171- 175. 31. W. L. Dills, Jr., W. M. L. Ho, and T. R. Covey, J. Carhohydr. Nucleosides Nucleorides, 8 (1981) 21 1-216. 32. R. H. White, Biochemistry, 17 (1978) 3833-3840. 33. R. H. White, Experientia, 36 (1980) 637-638. 34. A. Yokota and K. Sasajima, Agric. B i d . Chem.,50 (1986) 2517-2524. 35. M. Thensod, unreported experiments. 36. M. ThCrisod, D. Gaudry, and B. Estramareix, Nouv. J. Chim., 2 (1978) 119-121. 37. B. Estramareix and M. ThCrisod, Biochem. Biophys. Res. Commun., 95 (1980) 1017-1022. 38. E. R. Buchanan and E. M. Richardson,J. Am. Chem. Sue.. 67 (1945) 395-399. 39. R. E. Hill, A. Iwanow, B. G. Sayer, V. Wysocka, and I. D. Spenser, J . B i d . Chem., 262 (1987) 7463-7471, 40. R. E. Hill, B. G. Sayer, and I. D. Spenser, J . Am. Chem. Sue.. 111 (1989) 1916- 1917. 41. I. A. Kennedy, R. E. Hill, R. M. Pauloski, B. G. Sayer, and I. D. Spenser, J . Am. Chem. Soc., 117 (1995) 1661- 1662. 42. E. Wolf and I. D. Spenser, .I. Org. Chem., 60 (1995) 6937-6940. 43. A. Klemer and G. Rodemeyer, Chenz.Ber. 107 (1974) 2612-2614. 44. D. Horton and W. Weckerle, Carhohydr: Res. 44 (1975) 227-240. 45. J. C. Fischer, D. Horton. and W. Weckerle, Can. J. Chem., 55 (1977) 4078-4089. 46. P. E. Linnett and J. Walker, Biochem. J., 109 (1968) 161- 168. 47. P. E. Linnett and J. Walker, Biochim. Biophys. Acta, 184 (1969) 381-385. 48. R. L. White and I. D. Spenser, Biochem. 1..179 (1979) 315-325. 49. K. Yamada, M. Yamamoto, M. Hayashiji, K. Tazuya, and H. Kumaoka, Biochem. Int., 10 (1985) 689-694. 50. S. David and J. Renaut, Bull. Sue. Chim. Bid., 36 (1954) 1311 - 1317. 51. P. C. Newell and R. G. Tucker, Biochem. J., 100 (1966) 512-516. 52. P. C. Newell and R. G. Tucker, Biochem. .I., 100 (1966) 517-524. 53. P. C. Newell and R. G. Tucker, Biochem. J., 106 (1968) 271 -277. 54. P. C. Newell and R. G. Tucker, Biochem. J., 106 (1968) 278-287. 55. N. J. Cusack, B. J . Hilditch, D. H. Robinson, P. W. Rugg, and G. Shaw, J. Chem. Sue. ferkin Trans. I , (1979) 1720-1731. 56. B. Estramareix, Biochim. Biophys. Acta, 208 (1970) 170-171. 57. R. S. Tipson, J . Org. Chem.. 26 (1961) 2462-2464. 58. B. Estramareix and S. David, Biochim.Biophys. Acta, 1035 (1990) 154- 160. 59. A. S. Serianni, H. K. Nunez, and R. Barker, Carbohydr. Res., 72 (1979) 7 1-78. 60. M. L. Hayes, N. J. Pennings, A. S. Serianni, and R. Barker, J . Am. Chem. Soc., 104 (1982) 6764- 6769.
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S. J. Angyal, G. S. Bethell, and R. J. Beveridge, Curbohyd?:Res. 73 (1979) 9- 18. S. M. Love and B. Levenberg, Biochim.Biophys. Actu. 35 (1959) 367-373. B. Estramareix and M. ThCrisod, J . Am. Chem. Soc. 106 (1984) 3857-3860. B. Estramareix and S. David, Biochim. Biophys. Res. Commun., 134 (1986) 1136- 1141. A. C. Bratton and E. K. Marshall, Jr., J . B i d . Chem.. 128 (1939) 537-550. M. Franks, C. P. Green, G. Shaw, and G . J. Litchfield, J . Chem. SOC.C, (1966) 2270-2274. S. David and H. Hirshfeld,J. Chem. SOC.C, (1969) 133-137. K. Tazuya, M. Morisaki, K. Yamada, and H. Kumaoka, Biochem. Int., 16 (1988) 955-962. K. Tazuya, K. Yamada, and H. Kumaoka, Biochim. Biophys. Actu, 990 (1989) 73-77. K. Tazuya, C. Azumi, K. Yamada, and H. Kumaoka, Bitamin, 67 (1993) 68 1-688. K. Tazuya, K.Yamada, and H. Kumaoka, Biochem. Mol. Biol./nt., 30 (1993) 893-899. K. Tazuya, C. Azumi, K. Yamada, and H. Kumaoka, Biochem. Int., 12 (1986) 661-668. K. Tazuya, C. Azumi, K. Yamada, and H. Kumaoka, Biochem. Mol. B i d . Int., 33 (1994) 769-774. 74. H. S. M0yed.J. Bucferiol..88 (1964) 1024-1029. 75. T. Kawasaki andT. Nose,J. Biochem., 65 (1969) 417-425. 76. A. H. Stouthamer, P. G. de Haan, and H. J. J. Nijkamp, Genet. Res. Camb., 6 (1965) 442. 77. M. S. Brook and B. Magasanik,J. Bacteriol., 68 (1954) 727-733. 78. K. Yamadd, M. Morisaki, and H. Kumaoka, Biochim. Biophys. Acfu, 756 (1983) 41 -48. 79. H. Sanemori, Y. Egi, and T. Kawasaki, J . Bacteriol., 126 (1976) 1030- 1036. 80. J. H. Julliard and R. Douce, personal communication. 8 1. K. Tazuya, M. Morisaki, K. Yamada, H. Kumaoka, and K. Saiki, Biochem. Int.. 14 (1995) 253 1. 82. A. D. Backstrom, R. Austin, S. McMordie, and T. P. Begley, J. Am. Chem. Soc., 117 (1995) 2531 -2352. 83. G. E Joyce, Nature, 338 (1989) 217-224. 84a. D. M. Lonsdale, in A. Marcus (Ed.), Molecular Biology, p. 229, Academic Press, San Diego, Vol. 15, The Biochemistty of Plants, 1989. 84b. M. Sugiura, [bid. p. 133. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73.
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ADVANCES IN CARBOHYDRATE CHEMISTRY AND BIOCHEMISTRY, VOL. 52
MOLECULAR ARCHITECTURE OF POLYSACCHARIDE HELICES IN ORIENTED FIBERS
BY RENGASWAMI CHANDRASEKARAN Whistler Center for Carbohydrate Research 1160 Smith Hall, Purdue University West Lafayette. Indiana 47907, USA
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3 12 313 3 14 318 320 . . . . . . . . . . . . 326 IV. (1-+4)-Linked Polysaccharides . . . . 326 1. Cellulose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 333 2. Chitin . . . . 335 3. Mannan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337 ............ 340 348 353 ........................ 356 356 1. (I+3)-P-~-Glucan . . ................................... 36 I 2. ( 1 - + 3 ) - p - D - x y ~. ~ . . . . . . . . . . . . . . . . . . . . , . . , . . . . . . . . . . . . . . . . .. . . 36 1 ............................................... 3. ( 1+3)-lY,-D-GlUCan . . 362 364 366 368 370 .............................................. . . . . . . . . . . . 378 382 ........................ 383 383 385 389 393 395 ................................... 1. Xanthan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395 2. Galactomannans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 396 . . . . . . . . . . . . . . . . . . . . . . .
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Copyright 0 1997 by Academic Press. All nghts of reproduction In any form reserved.
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4. Rhizohium trifolii Capsular Polysaccharide .................. Acknowledgments ....... ............................... References ...................... ........ IX. Appendix ..................................................
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405
I. INTRODUCTION X-Ray diffraction from single crystals is the most direct and powerful experimental tool available to determine molecular structures and intermolecular interactions at atomic resolution. Monochromatic CuKa radiation of wavelength (A) 1.5418 8, is commonly used to collect the X-ray intensities diffracted by the electrons in the crystal. The structure amplitudes, whose squares are the intensities of the reflections, coupled with their appropriate phases, are the basic ingredients to locate atomic positions. Because phases cannot be experimentally recorded, the phase problem has to be resolved by one of the well-known techniques: the heavy-atom method, the direct method, anomalous dispersion, and isomorphous replacement.' Once approximate phases of some strong reflections are obtained, the electron-density maps computed by Fourier summation, which requires both amplitudes and phases, lead to a partial solution of the crystal structure. Phases based on this initial structure can be used to include previously omitted reflections so that in a couple of trials, the entire structure is traced at a high resolution. Difference Fourier maps at this stage are helpful to locate ions and solvent molecules. Subsequent refinement of the crystal structure by wellknown least-squares methods ensures reliable atomic coordinates and thermal parameters. Under crystallizing conditions, however, helical structures invariably grow much faster along the helix axis than in the other directions. Consequently, it is seldom possible to achieve the isotropic growth rate necessary to produce single crystals in the case of helix-forming polymers, such as polysaccharides, polypeptides, and polynucleotides. Although this is a major experimental impediment with noncrystalline polymers, it is often possible to prepare polycrystalline and/or oriented specimens in the form of fibers or films that are suitable for X-ray diffraction analysis. Such investigations have produced reliable helical models for a variety of native, as well as synthetic, polymer chains. Five articles on polysaccharide helices solved prior to 1979 have appeared in the volumes published between 1967 and 1982.2-6The first was a review on X-ray fiber diffraction and its application to cellulose, chitin, amylose, and related structures, and the rest were bibliographic accounts. Since then, X-ray structures of several new polysaccharides composed of simple to complex repeating units have been successfully determined, thanks to technological advances in fiber-diffraction techniques, the availability of fast and powerful computers, and the development of sophisticated software. Also, some old models have been either re-
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jected in favor of better substitutes or revised to greater precision, with the help of modem least-squares refinement protocols. According to current count, more than 50 well-defined polysaccharide X-ray structures are known from the literature. The main thrust of this chapter is to provide a detailed description of the molecular structures of the canonical forms. In every case, the morphology is illustrated in a stereo drawing. In addition to revealing the three-dimensional shape, it also shows, in most examples, the interactions of the helix with its neighbors in the crystalline state. The diagrams are very helpful for understanding the structural roles of cations and ordered water molecules on the associative properties of anionic polysaccharide chains. These interactions form the molecular basis of the observed functional properties of the polymer systems. Some fiber-preparation techniques and types of diffraction patterns from fibrous specimens are first described. The methodology for solving and refining helical structures using X-ray data is subsequently presented. The rest of the chapter is devoted to the three-dimensional structures of specific polysaccharides in oriented fibers. They include cellulose, mannan, chitin, and xylan, commonly known as structural poZysaccharides; the storage polysaccharide amylose and some of its derivatives: hyaluronan, chondroitin, keratan, and others in the glycosaminoglycan family; agarose, alginate, carrageenans, curdlan, gellan, and pectate (which are gel-formers); and branched polymers, such as galactomannan, welan, xanthan, and a few unrelated microbial structures. 11. POLYSACCHARIDE FIBERPREPARATION
To obtain good-quality X-ray data that are suitable for polysaccharide structure analysis, it is essential to induce axial, as well as lateral, organization of the long-chain molecules, as much as possible within the diffracting specimen. This can be achieved during the process of slow evaporation of a saturated polymer solution under controlled experimental conditions. The idea is to reduce entropy and thus increase the extent of three-dimensional ordering of the polymer molecules in a condensed state, be it a single crystal or not. The most commonly used method is to prepare a fibrous specimen from a polysaccharide solution, whose concentration is typically of the order of 2 mg/mL. A few drops of the solution are placed in the gap of approximately 2 mm between the beaded ends of two thin glass rods whose other ends are clamped in the threaded rods of a fiber puller and the solution is allowed to dry by gradually reducing the initial humidity of 100% surrounding the sample to about 80 or 75% over a period of 2 to 4 hours.’ Once the sample reaches a semi-solid state, the gap between the glass rods is gradually increased so that the specimen stretches without breaking and becomes a fiber, having dimensions of 5 mm or more in length and about 0.5 mm in thickness. It is then equilibrated at the desired humidity for a few hours. Finally, the glass rods with attached fiber are carefully removed from the puller,
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and are clamped in a small fiber holder, which can then be transferred to a flatfilm pin-hole camera for X-ray exposure. Another method is to cast films. Large drops of a concentrated polysaccharide solution on a Teflon block are allowed to dry overnight or longer. The film might have crystallinity, but not orientation. Strips of film, 5 by 10 to 15 mm, are cut and stretched under constant load, 500 mg to about 20 g, depending on the material, at 70 to 100%relative humidity (r.h.) for up to a week or longer. Stretching, up to 300% of the initial length, can yield good orientation of the polymer chains. In both methods, because crystallinity is influenced by temperature, humidity, co-solute, pH, etc., parameters relevant for the system have to be optimized for the best results.
111. X-RAYDIFFRAC~ION ANALYSIS
A fiber-diffraction pattern is recorded on a flat-film camera in which the fiberto-photographic film distance is typically in the range of 3 to 4 cm. During exposure to X-rays, the specimen chamber is continuously flushed with a slow and steady stream of helium gas that has been bubbled through a saturated salt solution so that (a) the fiber is maintained at a constant desired r.h. and (b) fogging of the photographic film from air scattering is reduced. The nature of a diffraction pattern is largely governed by the extent of molecular organization in the fiber, the building block of which is the unit cell of dimensions, a, b, and c conventionally expressed in A and interaxial angles a,p, and y in degrees (Fig. 1). This diagram shows a hypothetical polymer chain whose helix axis coincides with the c-axis. When the unit cells in the specimen have perfect three-dimensional periodicity, as in a single crystal (Fig. 2a), the diffraction corresponds to a series of reflections, which satisfy Bragg’s law: 2d sin0 =nh
(1)
where d is an interplanar spacing, 8 is the Bragg angle, and n is a positive integer. Although the position of a reflection is directly related to the unit-cell parameters, its intensity depends on the atomic arrangement. In other words, the observed intensity distribution is correlated to both molecular shape and molecular packing within and between the unit cells. Fibrous specimens, on the other hand, are far less ordered than the ideal single crystal, and they can be grouped under four major categories. The first corresponds to a randomly oriented assembly of microcrystallites. Figure 2b illustrates this situation schematically; for clarity, only two to three unit cells stacked along the c-direction are depicted per microcrystallite. In the absence of a clear definition, a microcrystallite is thought of as a tiny single crystal consisting of roughly three to four or more unit cells along each principal axis (u, h, or c). It is too small to produce a measurable signalhoke ratio when irradiated with
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FIG. I.-Schematic drawing of a hypothetical polysaccharide chain whose helix axis is along the c-edge of the unit cell.
X-rays. The diffraction from this polycrystalline and disoriented fiber is the sum of the diffraction from all the randomly oriented microcrystallites, and it corresponds to a series of concentric rings, each with its characteristic d-spacing. The intensity is uniform on a ring, but it varies among rings. This type of diffraction, commonly referred to as a powder pattern, is prevalent among minerals and polymers that have a low degree of polymerization.
A
FIG. 2.-Differenr types of diffracting specimens: {a) a single crystal (left) composed of threedimensionally periodic unit-cells and its diffraction pattern (right) containing Bragg reflections of varying intensities.
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C
FIG.2. (conrinuedj-(hj an assembly of randomly oriented microcrystallites (left) diffracts to produce a series of concentric rings (right); (c) an assembly of partially oriented blocks of microcrystallites (left) diffracts to produce large arcs (right).
When the fiber is stretched, longer blocks of unit cells might be facilitated, as shown in Fig. 2c. This falls under the second category, as the orientation of the large microcrystallites is no longer random, but somewhat tempered. Consequently, circles are trimmed down to arcs in the diffraction pattern in response to enhancement in orientation. The third category, shown in Fig. 2d, results when all of the long molecules or microcrystallites are aligned along the fiber axis, but they aggregate with little lateral ordering. This assembly, called an orientedfiber,diffracts to produce a series of layer lines that are perpendicular to the fiber axis. The intensity is nonuni-
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Mer idian 1=4 1=3 1=2
1=1 1=0 E q u a t o r 1=-1 1=-2
1=-3 1=-4
FIG. 2. (conrinued)--(d) an aggregate of microcrystallites whose long axes are parallel, but randomly oriented (left), diffracts to produce a series of layer lines (right); and ( e ) a polycrystalline and preferentially oriented specimen (left) diffracts to give Bragg reflections on layer lines (right). The meridional reflection on the fourth layer line indicates 4-fold helix symmetry.
form along any layer line and is directly related to the molecular transform. The d-spacing of the first layer line equals the c-repeat. The fourth category represents the state when the specimen is both crystalline and oriented as in Fig. 2e, and it is the best scenario for successful structure analysis. Note that the individual crystallites are large, with sufficient lateral
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ordering, and they are rotated differently about their long axes, which are nearly parallel to the fiber axis. The coupling of polycrystallinity with good alignment in a (stationary) fiber is equivalent to that of a rotating single crystal. Therefore, the diffraction pattern will show sharp Bragg reflections on layer lines at discrete positions that correspond to reciprocal lattice points. Figure 2e also sketches certain terms commonly used in fiber diffraction. The vertical line passing through the center, where the incident X-ray beam hits the film, is called the meridian and it is parallel to the fiber or helix axis, The horizontal lines are called layer lines, whose numbers start at 1 = 0 on the equator, increase upward, and decrease downward, as shown. Notice that no reflections are on the meridian, except for I = 5 4 . This indicates that the polymer forms a four-fold helix of pitch c. The two helical parameters, n (the number of repeats per turn) and h (axial rise per repeat) are 4 and 4 4 , respectively, in this example; also, t (the turn angle per repeat) is given by 360/n in degrees. Although t is positive for right- and negative for left-handed helices, h is reckoned positive in both cases. Any molecular model under consideration must satisfy the corresponding helical parameters. The distance of each reflection from the center of the pattern is a function of the fiber-to-film distance, as well as the unit-cell dimensions. Therefore, by measuring the positions of the reflections, it is possible to determine the unit-cell dimensions and, subsequently, index (or assign Miller indices to) all the reflections. Their intensities are measured with a microdensitometer or digitized with a scanner and then processed.*-1° After applying appropriate geometrical corrections for Lorentz and polarization effects, the observed structure amplitudes are computed. This experimental X-ray data set is crucial for the determination and refinement of molecular and packing models, and also for the adjudication of alternatives.
1. Computer Model Building and Refinement of Helical Structures In contrast to single-crystal work, a fiber-diffraction pattern contains much fewer reflections going up to about 3 8, resolution. This is a major drawback and it arises either as a result of accidental overlap of reflections that have the same 1 value and the same Bragg angle 9, or because of systematic superposition of hkl and its counterparts (-h-kl, h-kl, and -hkl, as in an orthorhombic system, for example). Sometimes, two or more adjacent reflections might be too close to separate analytically. Under such circumstances, these reflections have to be considered individually in structure-factor calculation and compounded properly for comparison with the observed composite reflection. Unobserved reflections that are too weak to see are assigned threshold values, based on the lowest measured intensities. Nevertheless, the number of available X-ray data is far fewer than the number of atomic coordinates in a repeat of the helix. Thus, X-ray data alone is inadequate to solve a fiber structure.
POLYSACCHARIDE HELICES IN ORIENTED FlBERS
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One way to circumvent this difficulty is to use existing stereochemical information. This includes bond lengths, bond angles, and some conformation angles, as derived from surveys of crystal structures of related monomers." An average or standard geometry for a sugar ring is an excellent starting point in polysaccharide structure analysis. Once the monosaccharide ring shape is fixed, three conformation angles (+, and are the only molecular variables needed to describe the geometry of the helix, instead of 33 coordinates for l l non-hydrogen atoms. This large decrease in the number of variables significantly increases the data-to-parameter ratio, and fiber-structure analysis becomes meaningful. The Linked-Atom Least-Squares (LALS) a n a l y ~ i s ' ~and . ' ~ the variable virtual bond (PS79) methodi4 constitute two important programs developed for the generation and refinement of fiber structures. Both are developed on the same basic principies. The LALS program has been extensively used to determine more than 100 structures to date; these include polysaccharides, polypeptides, polynucleotides, and polyesters. This program incorporates known information on bond lengths, bond angles, and conformation angles to describe a tree geometry for all of the atoms in one repeat, plus three adjoining atoms in the next repeat. The extra three-atom plane is necessary for achieving helix connectivity. In addition to refining the main chain and other relevant conformation angles, the positioning of the repeat is simultaneously adjusted by refining three Eulerian angles and a distance from the helix axis (z-axis) for a conveniently chosen root atom, until adjacent repeats conform to the desired n and h values. The function minimized by the LALS program is of the form:
+,
x)
R =Zw,AFn? +CunAT,2 +Ze,A0? +Z$Acj2 +ZA,C,
(2)
=X+Y+E+C+L
(3)
The first term (X) on the right side accounts for the sum of the squares of the differences (AF,,,) between observed (F,) and calculated (FJ X-ray structure arnplitudes of Bragg reflections. The second term ( Y ) accounts for the sum of the squares of the differences (ATn) between observed (To) and calculated (Tc) X-ray structure amplitudes of continuous diffraction. Either or both terms can be used as necessary. The third term ( E ) minimizes the differences (A0,) between expectedlstandard values ( 0 J , and corresponding conformation and bond angles (0J of the current model. The fourth term (C) includes both intra- and interchain hydrogen bonds, and the differences Acl between acceptable (do)and calculated non-bonded distances (dJ for those contacts that are smaller than the acceptable limiting values; this is designed to keep the model free from steric compression. The weights associated with these four types of observations are wm,un, el, and kl, respectively. Finally, the fifth term imposes constraints (Gh, with Lagrange multipliers A,) for helix connectivity and ring closure, and it vanishes when the constraints are satisfied. During the refinement, there is a provision to calculate structure factors with either normali5 or water-smeared atomic
320
RENGASWAMI CHANDRASEKARAN
scattering factors." The latter is particularly useful in studying hydrated fibers. An unobserved reflection is included in the refinement only when its F , value is larger than Fu. A number of alternatives have to be examined before choosing the best molecular model. They include (a) both right- and left-handed helices, and (b) single, as well as multistranded, helices with parallel and antiparallel strands. The next stage involves the packing arrangement in the unit cell. If two or more helices are present, according to the measured fiber density, their positions, orientations, and relative polarities have to be individually tested. The relative merits of E , X, Y, or competing models are assessed and compared on the basis of C; or in terms of the crystallographic R-values, R = ZIFo-F,I a F 0 and R = [ Zl Fu-FI.I *aF,2) using Hamilton's significance test." During the final stages of structure analysis, if good Bragg data are available, difference Fourier maps are excellent tools to locate ordered water molecules and/or cations that play a major role in the integrity of the helix and in the association of the helices. Also, the sugar rings are flexed by refining the endocyclic conformation angles. Endocyclic bond angles and the bond angle at the bridge oxygen atom are also varied. The accuracies of the final atomic coordinates are within a few tenths of an A and the R-values are typically around 0.2 in a majority of reported polysaccharide structures.
a,
2. Data Presentation Since the theory of helix diffraction was proposed" in the early 1950s, more than 200 biological and synthetic polymer helices have been successfully investigated to date by fiber diffraction techniques. At present, the number of polysaccharides in this class is larger than 50. In the beginning, molecular models were manually built and examined only by trial and error. With the arrival of computers in the 1960s, programs were developed to refine models against their X-ray data. About 30 atoms or less in a repeating unit were within the normal reach of many main-frame computers. To reduce the size of the problem, it was common to exclude hydrogen atoms while generating polymer helices. Thus, the coordinates of hydrogen atoms were not obtained for some structures solved in the 1970s. Because the scattering power of a hydrogen atom is low, omission of hydrogen atoms might not affect the X-ray results, but it does influence molecular morphology. Studies in the 1980s realized the importance of hydrogen atoms in generating stereochemically satisfactory molecular and packing models. Fast computers of the current decade and improved versions of compatible software have helped investigators to explicitly include hydrogen atoms in a routine fashion. Also, polymers with large and complex oligosaccharide repeats, which were not amenable before, are now feasible targets for X-ray analysis.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
32 1
This chapter provides a consolidated report of polysaccharide structures published in the past 40 years. Evidently, some are old and some are new; some are simple and some are complex. The quality of experimental data mirrors the precision of the final model in every case. Nevertheless, the conservation of conformation and diversity in chain packing are persistent features among related polymers. Important molecular details have been compiled and are listed in seven Tables. The helix type, single ( t ), double ( tt or tJ), or triple ( ttt ), and crystallographic unit-cell dimensions and space group for 47 polysaccharides, numbered from 1 to 47, are collated in Table I. When necessary, this number is used, rather than the full name of a polymer. In all cases, the fiber axis is parallel to the c-axis of the unit cell. The chemical repeating units are listed in Table 11. They range from a monosaccharide to a branched hexasaccharide. The distribution covers 21, 19, 3, 2, and 2 polymers composed of mono-, di-, tetra-, penta-, and hexa-saccharide repeats, respectively, but none with a trisaccharide repeat. On the basis of their linkage type, the polymers are further arranged in five groups: the first deals with (1-+4)-linked polysaccharides, the second with (1+3), the third with alternating (1+4), (1+3), the fourth with the gellan family of polysaccharides and, finally, the fifth with some branched polymers. A careful examination of the published atomic coordinates showed errors in some reports. They have been corrected properly and the revised coordinates are the input for generating the helical structures for this chapter. As various conventions were used in the original publications, there was confusion when comparing the conformation angles in related structures. This has been rectified by recalculating these parameters using a standard convention. The eclipsed cis conformation sets the dihedral angle to zero, and clockwise rotation of the farthest bond while looking along the middle bond is reckoned positive.62For the (1-n)-linkage, n being 1, 2, or 3, 4 and 9 refer to the dihedral angles 0 - 5 C-1-0-n-C-n and C-I-0-n-C-n-C-n 1. However, for the (1+6)-linkage, they are 0-5-C-1-0-6-C-6 and C-1-0-6-C-6-C-5, respectively. Unless otherwise specified, the hydroxymethyl group orientation, as in glucose, refers to the dihedral angle C-4-C-5-C-6-0-6. The orientation (6) of the acetamido group in glycosaminoglycans refers to C-3 -C-2 -N-C-7. For sulfate attachment to atom 0 - n , the two dihedral angles are 0, =C-n + I-C-n-0-n-S and 6, =C-n-0-n-S-0-S1. However, if n = 6, 6, =C-n-1-C-n-0-n-S. The helical parameters and major conformation angles of polysaccharides in the five groups are listed in Tables 111 to VII. The atomic coordinates of 31 selected helices are assembled in Tables A1 to A31 in the Appendix. Stereo and mono drawings are provided for a majority of structures so that the variety of molecular structures and their preferred packing arrangements can be readily visualized and compared among related members. The relevant figure and coordinates table for each helix can be inferred from the last two columns in Tables I11 to V (or rows in Tables VI and VII).
+
w N N
TABLE I Crystallographic Data on Polysaccharide Structures
No. 1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 16 17 18 19 20 21 22 23 24 25
Polymer Cellulose I Cellulose II Chitin I" Chitin II" Mannan I Mannan II (1 -4)-P-D-Xylan A-Amylose B-Amylase V-Amylose KOH-Amylose Tri-0-ethylmylose Na+ Pectate Pectic Acid Poly(P - D - M ~ A ) Poly(WL-GU~A) Curdlan 1 Curdlan I1 Curdlan 111 (1 - 3 ) - ~ - D - x y ~ ~ (1 + 3 ) - c ~ - ~ - G l ~ ~ a n Galactoglucan L-Carrageenan K-Carrageenan Agarose
Helm TYPe
t t
t t
r
t t Tt tt t
t t T f
t t t ttf rtt ttt f t tf tt tt
a
Unit-cell Dimemsions b c
8.17 8.01 4.85 4.74 8.92 9.00 9.16 21.24 18.50 12.97 8.84 15.36 8.39 9.9 8.6 10.7 28.8 15.56 14.41 15.4 16.46 14.49 13.73
7.86 9.04 9.26 18.86 7.21 16.65 9.16 11.72 18.50 22.46 12.31 12.18 14.27 12.3 1.6 8.6 18.6 15.56 14.41 15.4 9.55 9.79 13.73
...
...
...
. I .
10.38 10.36 10.38 10.32 10.27 10.35 14.85 10.69 10.40 7.91 22.41 15.48 13.36 13.3 10.4 8.7 22.8 18.78 5.87 6.12 8.44 15.89 13.28 25.0 9.5
Y 97.0 117.1 97.5 90.0 90.0 90.0 120.0 123.5 120.0 90.0 90.0 90.0 90.0 90.0 90.0 90.0 90.0 120.0 120.0 120.0 90.0 90.0 120.0
... ...
Space Group
I222 P3,21 B2
p2;2,2, p21212, PI Pl P6, P6, p21212, p2,2,21 P3,12 ...
...
Reference
24 25 26 21
32 33 34 35 36 37 38 39 40 41 42
n
z
26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Na+ Hyaluronate I Na+ Hyaluronate I1 K+ Hyaluronate I K+ Hyaluronate U Na+ Hyaluronate 111 Ca2+Hyaluronate K+ Hyaluronate Na+ Chondroitin 4SO; K+ Chondroitin 4SO; Ca" Chondroitin 4.30; Na+ Dermatan 4SO; I Na' Dermatan 4SO; I1 Na' Dermatan 4SO; Ill Keratan 6-sulfate Li+ Gellan K+ Gellan K+ Native Gellan Ca2+WeIan Xanthan Galactomannan Escherichia coli M41 CPS' Rhizohium trifolii CPS'
t t t t t t
Lt
t t t t t t t tt tt tt tt
?
t t T
9.89 11.53 9.96 11.73 11.70 20.93 17.14 14.52 13.85 7.45 14.60 11.51 12.67
9.89 9.89 9.96 9.25 1 1.70 20.93 17.14 14.52 13.85 17.81 14.60 10.65 12.67
...
...
15.60 15.75 16.47 20.83 29.0 9.3 20.3 16.8
15.60 15.75 16.47 20.83 24.9 30.8 11.78 9.7
33.94 33.86 37.88 35.42 28.50 28.30 32.8 28.32 27.73 19.64 28.23 18.78 73.53 18.9 28.20 28.15 28.42 28.69 47.0 10.3 30.44 20.2
90.0 90.0 90.0 90.0 120.0 120.0 90.0 120.0 120.0 90.0 120.0 90.0 90.0
... 120.0 120.0 120.0 120.0 90.0 90.0 90.0 90.0
43 43 44 45 46 47 48 49 50 51 52 52 52 53 54 55 56 57 58 59 60 61
Note: a. b. and care in A. a=P= 90 and y are in degress. a Chitin I and U were originally termed P- and a-chitin, respectively. Non-half-staggered double helix. Capsular polysaccharide.
W W N
W
P N
TABLE II Chemical Repeating Units of Polysaccharides Polymer
No.
1-2 3-4 5-6 7 8-11 12 13-14 15 16 17-19 20 21 22 23 24 25 26-32 33-35 36 -38 39 40-42 43
Cellulose Chitin Mannan (1 +4)-P-D-Xylan Amylose 2,3,6-Tri-O-ethylamylose Pectate Poly(P-D-mannuronic acid) Poly(a-L-guluronicacid) Curdlan (1 +3)-P-D-xylan (1 3)-cY-D-GlUCan Galactoglucan damageenan K-Carrageenan Agarose Hyaluronan Chondroitin4-sulfate Dermatan 4-sulfate Keratan 6-sulfate Gellan Welan
-
-
Repeating Unit
4)-P-~-Glc-( 1 4)-P-o-GlcNAc-(1+ 4)-P-~-Man-(1 -4)-P-D-Xyl-( 14)-a-D-Gk-(1 + -+ 4)-2,3,6-EG-a-D-Gk-( 1 -+ 4)-a-~-GalA-( 1+ 4)-P-o-ManA-(1 -~)-~-L-GuLA-(1 + 3)-P-D-GlC-(1 3)-p-D-xyl-( 1 + -+ 3)-a-D-Glc-(1 + +3)-P-~-Glc6Ac-( 1 +3)-c-o-Gal4,6-Pyr-(1 -+ ~ ) - P - D - G ~ ~ S O1;+ - ( 4)-3,6-An-a-~-Ga12SO;-(1+ +3)-P-~-Ga14SOy-( 1 -+ 4)-3,6-An-m-o-Gal-( 1-+ 1 +4)-3,6-An-a-~-Gal-(1 4 -+ 3)-P-~-Gal-( 4 ~)-P-D-GIcNAc-( 1 -+4)-P-D-GkA-( 1 + +3)-p-~-GalNAc4SO;-( 1 +4)-P-o-GlcA-( 1+ -+ 3)-P-D-GalNAc4SO,-( 1 -4)-a-~-IdoA-( 1 3)-P-~-Ga16SOi-(1 4)-P-~-GlcNAc6S0;-( 1+ +3)-P-D-Gk-(1 4)-P-D-GkA-(1 +4)-P-D-Gk-( 1 +4)-a-~-Rha-( 1 +3)-P-D-Gk-(1 +4)-P-D-GlCA-(1 +4)-P-D-GlC-(1 +4)-a-L-Rha-(1 2 3 -+
-+
-+
-
-
-+
-+
-+
--
-+
t OAc
-
-+
-+
t 1
a-L-Rha or a-L-Man
44
Xanthan
45
Galactomannan"
-P
4)-P-~-Man-(1 + 6
f
1
(a-D-Gd)>
46
Escherirhia roli M41 CPSb
---*
2)-a-D-Man-( 1 +3)-P-~-Glc-(1 +3)-p-~-GlcA-(1 43)-a-~-Gal-(1 + 4
t
1 p-o-Glc4,6-Pyr-( 1 +2)-a-D-Mm 41
Rhizobium trifolii CPS'
@+-Gal-( 1 +4)-P-D-Gd 1
.1 6 +4)-a-D-G1C-( 1 +3)-a-~-Man-( 1 +3)-P-~-Gal-(l-+ 2
t
1 a-D-Gal Nore: All monosaccharide residues are pyranosyl tautomers. a The distribution of galactose residues is irregular such that the occupancy x is either zero or I . UI> is 0.6 in guaran. Capsular polysaccharide.
zi
m m
E
326
RENGASWAMI CHANDRASEKARAN
I v . (1+4)-LINKED POLYSACCHARIDES Three distinct classifications are possible in this group of polysaccharides having monosaccharide repeating units. Cellulose, mannan, chitin, and xylan belong to a family of structural polysaccharides and, except for xylan, they display similar ribbon-like molecular morphologies. Amylose and its derivatives are members of the storage polysaccharide family and they exist in numerous polymorphic forms. Alginate and pectate are industrially useful gel-forming polysaccharides. Examination of data presented in Table I11 affords some insight into the extent of variety, as well as the conservation of conformation. All polymers, except 16, have 4C, pyranose rings in their main chains. The three-dimensional structures presented here are helpful to correlate with the observed physical properties.
1. Cellulose At least four crystalline allomorphs (I, 11,111, and I V ) are known for cellulose from studies by X-ray diffraction and infrared spectroscopy. Among them, native cellulose fibers from Valonia,ramie, cotton, and woods, referred to as cellulose I (l),and the fibers produced after regeneration or mercerization, referred to as cellulose I1 (2),form the two major families. Despite some X-ray and electrondiffraction investigations on forms 11163 and IV,64 which are derived by heat or alkali treatment from forms I and 11, their structural details remain elusive. The first X-ray diffraction established that (a) the cellulose chain forms a 2-fold helix of pitch 10.3 A; (6) the monoclinic unit cell, a = 8.35, b = 7.9, c = 10.3 A, and y = 96", accommodates two chains (a total of four glucose residues) passing through (000) and (%!40), respectively; and (c) an antiparallel packing is preferred over a parallel alignment of both chains. From a historical perspective, these results form a milestone in cellulose crystallography. Since then, these molecular features have become widely accepted and repeatedly confirmed by several independent studies. However, the packing arrangement originally proposed has met with serious criticisms, specifically in relation to the biosynthesis of cellulose.
a. Cellulose I (l).-Gardner & Bla~kwell'~ used the LALS program to define the molecular structure and to propose the correct packing arrangement of Valonia cellulose I. The ribbon-like 2-fold helix of pitch 10.38 8, is stabilized by a series of 3-OH.a.0-5 hydrogen bonds (2.75 A) formed across each glycosidic oxygen atom. The main-chain conformation angles (Table 111) are near the global energy minimum for an isolated cellulose chain. The X-ray data consist of 36 out of 39 reflections that fit the monoclinic unit cell. Note that the three reflections not indexable by this cell were omitted from the structure analysis. On the basis of a significantly lower R-value of 0.18, as compared to 0.21 for the antiparallel packing, the parallel model was adjudged to be the best for cellulose I.
-
TABLE In Helical Parameters and Conformation Angles in (1
No.
Polymer
Cb
ch>
7
114.8 114.8 114.8 114.8 114.9 117.0 117.0 116.5 117.4 117.0 113.6 123.0 115.8 116.3 119.7
2
Cellulose I Cellulose LI"
180 180
5.19 5.18
3 4 5
Chitin Ih Chitin IIb Mannan I'
180 I80 180
5.19 5.16 5.14
6 7 8
Mannan I1 (1 +4)-p-D-xylan A-Amylosed
180 - 120 - 60
5.18 4.95 3.56
9
B-Amylosed
-60
3.47
10
V-Amylose
-60
1.32
1
4)-linked Polysaccharides
+
4J
X
-98 - 96 -96 -98 -94 -90 -90 -88 -58 92 86 93 84 84 115
-143 - 145 -145 - 143 - 150 -149 -149 - 153 - 109 -153 - 145 - 150 - 144 -144 -131
-81 174 - 70 55 -123 175 -175 - 23 50 62 56 53 68 -168
Fig.
Table
3
A1
4 5 -
A2 -
6.7 8 9
A3 A4
10
A5
11
A6 A7
12
(continued)
3 W m
I2
W
4 N
TABLE 111 (continued)
No. 11
12
13
14 15 16
Polymer KOH-Amy losed
2,3,6-Tri-O-ethylamylose Na' Pectate'
Pectic Acid Poly( P - D - M ~ A ) POI~(CX-L-GUIA)
CIS
ch>
7
-60
3.74
115.6 116.3 113.7 122.1 116.5 116.5 116.5 116.5 117.1 117.6
-90
120
120 180 180
3.87 4.45
4.43 5.20 4.35
+
*
93 92 92 64 80 80 80 73 -94 -108
- 149 -151 - 162 90 90 90 97 -145 -134
- 150
W N 00
X 57 68 -68 -94 115
Fig.
Table
13 14
A8 A9
15,16 17 18 19
A10 A1 1 A12 A13
91
99 93 94 99
Nore: in & . are the average helical parameters per monosaccharideresidue. T is the bridge bond angle C-l-O4-C4. The three conformation angles are +(0-5-C-l-04-C4), $(C-l-04-C-4-C-5) and x(C-4-C-5-(2-6-0-6 or 0-61). a The two chains in the unit cell are conformationallyindependent. Orientation of the acetamidogroups, x(C-3-C-2-N-C-7). is -134" in 3 and -133" in 4. ' The two residues per turn are conformationallyindependent. dRepeating unit is a maltotriose in 8 and 11, and maltose in 9. ' The three residues per turn have slightly different carboxylate group orientations.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
329
A
B
FIG.3.-Parallel packing arrangement of the 2-fold helices of cellulose 1 (1).(a)Stereo view of two unit cells approximately normal to the ac-plane. The two comer chains (open bonds) in the back, separated by a, form a hydrogen-bonded sheet. The center chain is drawn in filled bonds. All hydrogen bonds are drawn in dashed lines in this and the remaining diagrams. ( b ) Projection of the unit cell along the c-axis, with a down and b across the page. No hydrogen bonds are present between the comer and center chains.
330
RENGASWAMI CHANDRASEKARAN
The lateral ordering of the chains produces hydrogen-bonded sheets parallel to the ac-plane, as shown in Fig. 3a. This is accomplished through an interplay between the molecular structure and packing parameters. Each hydroxymethyl group adopts a tg (namely C-6-0-6 trans to C-5-0-5 and gauche minus to C-5-C-4) conformation [x = -81’1 so that intrachain 2-OH-..0-6 (2.87 A), as well as interchain 6-OH-e.0-3 (2.79 A), hydrogen bonds are optimized. An axial projection of the unit cell is shown in Fig. 3b. The relative displacement between the comer and center chains (sheets) along the fiber axis is 0.27c, and it leads to good stacking interactions among the pyranosyl rings. These structural features are responsible for the strength and rigidity displayed by the crystalline regions of cellulose. Similar results were simultaneously published by Sarko and and any differences between the two studies are only marginal. b. Alternate Unit Cells for Cellulose I?-Results from subsequent work67 on ramie and Valonia cellulose I structures are virtually the same in every respect. However, Takahashi and Matsunaga6’ have implicated a statistical packing arrangement in which the sheets are randomly distributed in the ratio of 0.7 “up” and 0.3 “down” at the comer, and 0.5 “up” and 0.5 “down” at the center for improving the X-ray fit. The inclusion of these four occupancy parameters as additional variables results in a lower R-value (0.12)-0nly at the expense of (weakening) the “cellulosic” 3-0H.. . O-5 hydrogen bonds (3.16 A); therefore, the odds are very slim. All indications to date conclude that the cellulose I chains pack in the parallel sense. The three reflections omitted in the Valonia analysislg are not easy to ignore because they correspond to the fine structural details of the crystalline phase. They can be accounted by two alternatives. The first is an eight-chain super monoclinic cell, having a and b double the corresponding values in the twochain unit cell: however, a few of the eight chains have to be crystallographically noneq~ivalent.l~*~~ Although this large cell introduces statistical packing of the sheets with different translations, chains exhibiting different orientations of the hydroxymethyl groups, etc., the analysis is tedious and the results are too complex for ready comprehension. The second choice is a simpler solution. According to Sarko and all 39 observed reflections in the Valonia X-ray pattern are indexable by a twochain triclinic unit cell with a = 9.41, b = 8.15 and c = 10.34 A, IX = 90°, p = 57.5”, and y = 96.2”. Ramie cellulose, on the other hand, is completely consistent with the two-chain monoclinic unit cell. Also, there are significant differences between their high-resolution solid-state NMR spectra, indicating that Valonia and ramie celluloses, the two most crystalline forms, reflect two distinct families of biosynthesis. On this basis, the Valonia triclinic and the ramie monoclinic forms are classified69as Ia and ID,respectively. It has been shown from a systematic analysis of the NMR spectra by these authors, and from electron-dif-
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
33 I
fraction data and Fourier-transform infrared spectra7’q7’ that all other native celluloses can be represented by a mixture of Ia and I, in different proportions. Visualization of crystal structures in these cases is difficult. The triclinic form can be transformed into the monoclinic form in the solid state. Annealing experim e n t ~in~Vuloniu ~ cellulose demonstrate that temperature (up to 260°C) is the determinant for the observed Ia+$ irreversible transition.
c. Cellulose I1 (2).-The material obtained from native cellulose-either by a solution-regeneration process or by mercerization (involving a swelling treatment with alkali)-is referred to as cellulose 11. Fiber-diffraction analysis2’ of this crystalline form has revealed a 2-fold helix as its molecular structure whose backbone is isomorphous with that of 1. Two cellulose chains pass through the unit cell the same way as in 1, except that they run antiparallel. Both chains maintain the 3-OH...0-5 (2.69 A) hydrogen bonds. The X-ray results (final R-value = 0.17 for 44 observed reflections) show that the hydroxymethyl orientations are gt and tg, respectively, for the comer and center chains. Consequently, 2-OH...0-6 (2.73 A) bonds are present only in the “down” center chains, which form a sheet in the 020 plane and exhibit interchain 6-0H.. - 0 - 3 (2.67 A) hydrogen bonds (Fig. 4a). The “up” comer chains, connected by 6-OH...0-2 (2.76 A) bonds, also form a sheet structure; their 2-OH groups make a new set of 2-OH...0-2 (2.77 A) bonds in the I10 plane with a neighboring center chain. In other words, adjacent antiparallel sheets are now connected. Because of this additional linkage, cellulose I1 is energetically more stable than cellulose I. The relative orientations of the comer and center chains, which are significantly different from 1, can be visualized from the axial projection of the unit cell (Fig. 4b). Similar results have also been published e l ~ e w h e r eIt. ~is~ now well known that the transformation of cellulose I to cellulose 11, from parallel to antiparallel packing, is irreversible. Logically, therefore, it is believed, that I is a metastable structure and I1 is the stable form of cellulose. According to a recent report, the unit cell of cellotetraose hemihydrate in single crystals contains two antiparallel chains, which are conformationally distinct-especially in the sugar g e ~ m e t r i e sHowever, .~~ all hydroxymethyl groups adopt similar g t orientations. Whether this oligosaccharide morphology can be implemented for cellulose I1 in fibers remains to be seen. d. Cellulose Derivatives.-Fiber diffraction analyses have confirmed that the ribbon-like chain conformation is conserved in several chemically modified cellulose derivatives. Cellulose I t r i a ~ e t a t ecellulose ,~~ I1 t r i a ~ e t a t ecel,~~ lulose I1 hydrate,77and cellulose 11- hydrazine complex7* are some examples. In every case, there is considerable swelling of the unit cell in a plane normal to the helix axis in order to accommodate the non-cellulosic components. Parallel and antiparallel packing arrangements are preserved in type-I and type-I1
FIG.4.-Antiparallel packing arrangement of the 2-fold helices of cellulose I1 (2). (a) Stereo view of two units cells approximately normal to the ac-plane. The two comer chains (open bonds) in the back form a hydrogen-bonded sheet. The center chain (filled bonds) is linked to the comer chains by hydrogen bonds. (h) Projection of the unit cell along the c-axis and a is down the page.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
333
derivatives, respectively. The unit cell of cellulose I triacetate has four chains, two up and two down, related by P2,2,2, ~ymrnetry.’~ Because all potential hydroxyl groups are substituted in these structures, neither intra- nor interchain hydrogen bonds exist. Packing of the chains is facilitated only by van der Waals forces. In contrast, adjacent cellulose chains are linked by hydrogen bonds via hydrazine molecules, which are present one per glucosyl unit, in the hydrazine Examination of these and other related cellulose structures reveals that the variety of packing arrangements originates through the exploitation of the full range of C-5 -C-6 rotation to maximize intermolecular interactions.
2. Chitin Chitin is the most abundant polysaccharide composed exclusively of amino sugars and has distinct fundamental characteristics. As a (1+4)-linked polymer composed of ~-acetyl-~-D-glucosamine as the building block, it is a good replacement of cellulose as the structural entity in the cell walls of many species of lower plants, such as fungi, mycelial yeasts, green algae, brown and red algae, and in the skeletal tissues of lower animals, including arthropods (notably crabs and lobsters), and mollusks. Thus, it is not surprising that chitin adopts a 2-fold helical conformation similar to that of cellulose. Three crystalline modifications, a,P, and y, are known from X-ray diffraction studies. Of these, the a and P forms are analogous to cellulose I1 and I, respectively, in terms of chain packing, and their structural details have been characterized to varying extents. Henceforth, chitin I (3) will denote P-chitin and chitin I1 (4) a-chitin. The y-form, however, is still unsolved. a. Chitin I (3).-This form crystallizes in a one-chain monoclinic unit The cellulose-like 2-fold helical structure has been refined to a final R-value of 0.27 for 60 X-ray data. The orientation of the trans planar acetamido group is roughly perpendicular to the pyranose ring, and that of the hydroxymethyl group is gg. The only intrachain hydrogen bond 3-OH..-0-5 (2.75 A) keeps the backbone fairly rigid, as in cellulose. The molecular structure and intermolecular interactions are illustrated in Fig. 5a. Polarities of all the chains are the same in the crystalline lattice. The short lateral separation (4.85 A) along the a-axis leads to overlapping of the pyranose rings between chains. This stacking is further stabilized by two interchain hydrogen bonds, NH . * 0-7 (2.76 A) and 6 - 0 H . .. O-7 (2.89 A). A projection of the unit cell along the c-axis is shown in Fig. 5b. The absence of hydrogen bonds between chains in the bc-plane offers a structural explanation for the relative ease with which chitin I can be swollen in water to produce chitin hydrates.
b. Chitin I1 (4).-X-Ray and mfrared analysis2*is one of the oldest structural investigations and the details might not be as accurate as would be desired for 4. The molecule exhibits cellulose-like conformation angles in the backbone and, hence, the 3-0H. 0-5 hydrogen bond (2.68 A) is preserved. The hydroxy-
334
RENGASWAMI CHANDRASEKARAN
P
B
d FIG.5.-Parallel
packing arrangement of the 2-fold helices of chitin I (3). (a) Stereo view of two unit cells approximately normal to the bc-plane. The two comer chains (open bonds), separated by h, in the back are hydrogen bonded to the comer chains (filled bonds) in the front. (b) Projection of the unit cell along the c-axis with u down and b across the page. The diagonal orientation of the sugar rings facilitates interchain hydrogen bonds involving the N-acetyl moieties along the a-axis.
methyl group is statistically disordered so that x corresponds to either the trans or gauche domain, the mean value being - 123". The acetamido group is roughly normal to the pyranose ring, as in 3. The two chains passing through (OOO) and (%%O) of an orthorhombic unit cell are antiparallel and related by space group symmetry. They are linked by weak 6-0H.. . O-6 (3.3 A) hydrogen bonds. Further, NH ... O-7 hydrogen bonds (2.69 A) exist between similar chains, separated by the a-axis. Thus, because of the acetamido groups, there are more intra- and inter-chain hydrogen bonds in 3 and 4 than in 1 and 2. Because of the polarity problem, the chitin 1-11 transition is also irreversible, as in the case of cellulose.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
FIG.6.-X-Ray of 10.27 A.
335
diffraction pattern from mannan I (S), showing 2-fold helix symmetry and a c-repeat
3. Mannan Microfibrils of mannan are present in the cell walls of ivory-nut endosperm and date seeds, and the granular form of mannan occurs in siphoneous green algae.7yTwo distinct crystalline forms, I and 11, represent the native and alkalitreated material, respectively. An X-ray diffraction pattern from mannan I is shown in Fig. 6. In both forms, mannan chains are isohelical to cellulose, although the 2-OH group in mannose is axial (instead of equatorial), as in glucose. The packing arrangements of the 2-fold helices of mannan I and I1 differ considerably, although antiparallel chains are the common features.
a. Mannan I (5).-Early X-ray s t ~ d i e s ~proposed ~ , ~ " a ribbon structure for mannan I using non-hydrogen atoms only. The most recent X-rayz3and electrondiffraction" analyses have included the hydrogen atoms; accordingly, the structure is better defined. They show that 5 crystallizes in a two-chain orthorhombic unit cell. The two chains passing through (000) and (%2!40)are related by crystallographic screw axes perpendicular to the chain direction and, hence, are antiparallel. According to the X-ray results, the backbone conformation angles are = -90" and $ = - 149", and the hydroxymethyl group orientation is g t , but x
+
336
RENGASWAMI CHANDRASEKARAN
n
B
d
FIG.7.-Antiparallel packing arrangement of the 2-fold helices of mannan I (5). (a) Stereo view of two unit cells approximately normal to the hc-plane. The two comer chains (open bonds) in the back are not hydrogen bonded to each other. The antiparallel center chain (filled bonds) is linked to the left comer chain by 2-0H.. 0 - 5 bonds. ( b ) Projection of the unit cell along the c-axis; the a-axis is down the page. This highlights the hydrogen bonds between the comer and center chains.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
331
alternates between 175 and - 175”in successive residues. The molecule is stabilized by two intrachain hydrogen bonds, 3-OH -. 0 - 5 (2.58 A) and 6-0H.. ,O-3 (3.0 A). The molecular geometry and intermolecular interactions are illustrated in Fig. 7a. The comer and center chains are connected by 2-OH...0-5 (2.93 A) hydrogen bonds. As shown in Fig. 7b, the sugar rings are somewhat rotated from the hc-plane. Notice that 4, $, and x are -81, -161, and 149”, respectively, in the electron-diffraction study.8’ Any conformational and, hence, packing differences between the two independent investigations are perhaps not significant.
b. Mannan I1 (6).-X-ray a n a l y s e ~ ~ show ~ . ’ ~ that 6 crystallizes in a fourchain orthorhombic unit cell. The two “up” and two “down” chains, related by crystallographic dyads normal to the c-axis, are conformationally identical. The molecular structure is essentially the same as that of 5, except that the hydroxymethyl group is in the tg conformation. As the packing diagrams in Fig. 8 show, antiparallel strands connected by 6-0H.. . O-6 (2.6 A) hydrogen bonds form sheets almost parallel to the b ~ - p l a n e .In~ ~addition, a water molecule ( W ) on a two-fold rotation axis per mannose residue forms an intersheet 0 - 2 ..W . ..O-2 bridge (0...W = 2.9 A) and provides additional stability to the mannan I1 structure. Cellulose, chitin, and mannan are chemically simple and related biopolymers. The latter two differ from cellulose primarily in configuration or substitution at C-2 of P-D-glucose. Nonetheless, all of them display similar ribbon-like molecular shapes. The robustness of their main-chain conformation originates from the 3-OH...0-5 hydrogen bond. However, structures 1 to 6 have quite different packing arrangements. This appears to be a consequence of the variability in interchain interactions. The parallel chain packings for cellulose I and chitin I are compatible with concepts of the biosynthetic mechanisms that produce the very long microfibrils and spines.23 This hypothesis is readily understood, but it leaves open the question of how chitin 11, mannan I, and mannan 11, also native polymers, achieve biosynthesis of antiparallel chains. 4. (1+4)-P-~-Xylan Among the naturally occumng polysaccharides built up of P-D-xylose repeating units, both (1-4) and (1-+3)-linked polymers have received some attention. Because xylose has only a 6-H atom in place of the 6-CH20H group in glucose, it is logical to expect the two polymers to be analogous to cellulose and curdlan, respectively. One of the principal hemicelluloses, constituting up to 35% of the dry weight of hardwoods, is the polysaccharide (1+4)-P-D-xylan (7). X-ray data from hydrated xylan fibers25are compatible with a trigonal unit cell, and meridional reflections on 1 = 3n are diagnostic of 3-fold helix. A
RENGAS WAMI CHANDRASEKARAN
338
B
FIG.%-Packing arrangement of four symmetry-related 2-fold helices of mannan I1 (6).(a) Stereo view of two unit cells approximately normal to the bc-plane. The two chains in the back (open bonds) and the two in the front (filled bonds) are linked successively by 6 - O H . . . 0 - 6 bonds. The front and back chains, both at left and right, are further connected by 0 - 2 . . . W . ..0-2 bridges. (b) Projection of the unit cell along the c-axis; the a-axis is down the page. This highlights the two sets of interchain hydrogen bonds between antiparallel chains, distinguished by filled and open bonds. The crossed circles are water molecules at special positions.
left-handed 3-fold helix fits the data better than a right-handed helix. The molecular geometry (Fig. 9a) has 117.4' for the bond angle at the bridge oxygen atom. A cellulose-like 3-OH...0-5 (3.16 A) hydrogen bond stabilizes the sinuous helix. The two antiparallel chains passing through (%%O) and (%%O) of the unit cell satisfy the space-group symmetry, P3,21 (Fig. 9b). A spine of six consecutively hydrogen-bonded water molecules, one per xylose residue, is fur-
POLYSACCHARIDE HELICES LN ORIENTED RBERS
339
FIG.9.-Antiparallel packing arrangement of the 3-fold helices of (1+4)-P-D-Xyh (7). (a) Stereo view of two unit cells roughly normal to the helix axis and along the short diagonal of the ab-plane. The two helices, distinguished by filled and open bonds, are connected via water (crossed circles) bridges. Cellulose type 3-OH...0-5 hydrogen bonds stabilize each helix. (6) A view of the unit cell projected along the c-axis highlights that the closeness of the water molecules to the helix axis enables them to link adjacent helices.
ther linked to atoms 0 - 2 and 0-3, establishing water bridges between chains. There are, however, no direct interchain hydrogen-bonds in the crystal structure. A similar molecular structure is also proposedx2 for the gummy polysaccharide from corm sacs of Wutsoniu pyrumidatu in which the (1+4)-xylan backbone is highly substituted with 2- as well as 3-linked L-arabinofuranosyl side
340
RENGASWAMI CHANDRASEKARAN
chains. Although this might suggest that bulky substituents have no detectable influence on xylan morphology, an earlier X-ray analysis on xylan diacetateX3 has shown that the 0-acetyl groups at C-2 and C-3 confine this polymer to a cellulose-like two-fold helix of pitch 10.31 A. No water molecule is found in its two-chain monoclinic unit cell. The molecular structure and interhelix interactions are both dominated mainly by van der Waals forces. Energetically, an isolated chain will prefer only a two-fold helix in all three cases. Based on the X-ray results, the packing effects are reckoned to be the source for the ability of xylan dia~etate?~ and the inability of both ~ y l a n 'and ~ its related branched polymer.'* to assume a two-fold helical structure.
5. Amylose Starch is the storage polysaccharide of D-glucose in plants. Its two major components are the linear ( 1-4)-a-~-glucan amylose and the branched polysaccharide amylopectin, which contains (1-4) and (1+6)-links. The relative amount of these two components varies with the species and hybrid form of starch. For example, high-amylose corn starch has up to 70% amylose, waxy maize starch has about 98% amylopectin and less than 2% amylose, and potato starch has 21% amylose. Two principal types of crystalline starch granules are the A-starch of cereals and the B-starch of tubers. X-Ray diffraction patterns suggest that the starch molecules exist as helices in both cases.84A third, rare, so-called type-C starch, found in some plants, yielding distinctive diffraction patterns, is now recognized to be a mixture of the A- and B-forms. Polycrystalline and well-oriented specimens of pure amylose have been trapped both in the A- and B-forms of starch, and their diffraction pattern^'^.'^ are suitable for detailed structure analysis. Further, amylose can be regenerated in the presence of solvents or complexed with such molecules as alcohols, fatty acids, and iodine; the molecular structures and crystalline arrangements in these materials are classified under V-amylose. When amylose complexes with alkali or such salts as KBr, the resulting structuresx6are surprisingly far from those of V-amyloses.
a. A-Amylose @).--Solid-state deacetylation of oriented and crystalline amylose triacetate fibers with 0.2 M KOH in 75% ethanol, followed by exposure to 80% or higher r.h. at temperatures of 85°C or higher gives rise to pure A - a m y l ~ s e X-Ray . ~ ~ diffraction patterns were indexedx4on an orthorhombic unit cell of dimensions a = 11.9, b = 17.7, and c = 10.52 A. Consistent with the presence of meridional reflection on the third layer line, the authors proposed a 6-fold, right-handed, half-staggered parallel double helix of pitch 2c or 21.04 8, as a possible molecular model. A conspicuous feature is the relatively low bond angle (T = 105") at the glycosidic bridge oxygen atom. Two antiparallel-packed double helices pass through (000) and (%%O) of the
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
34 I
cell. Thus, half-a-turn per double helix and eight water molecules are present in the unit cell. However, the antiparallel packing of helices has been questioned from biosynthetic considerations that favor all amylose chains to be paralle1.88.89 With the aid of newly collected X-ray powder and electron microcrystal diffraction data, in conjunction with the X-ray fiber data of Wu and S a r k ~ Im,~~ berty et a1.26re-examined and rejected the previous model. Powder patterns were from pure amylose (DP 15), obtained after mild hydrolysis of potato starch. Electron-diffraction data were from micro single crystals grown from the same material. These, as well as the original X-ray fiber datas4 after re-assignment of indices, are compatible with a monoclinic unit cell that accommodates 12 glucose residues (a maltotriose/asymmetric unit) and four water molecules in order to be compatible with the fiber density of 1.51 g/mL. The space group is B2 and the final structure corresponds to a 6-f0ld, left-handed, parallel double helix of pitch 21.38 A. Two double helices, having the same polarity, pass through (000) and (
FIG.10.-Parallel packing arrangement of 6-fold. A-amylose (8) molecules. (a) A stereo side view of less than 2 turns of a pair of double helices 10.62 A (=a/2)apart. The two strands in each helix are distinguished by open and filled bonds, and the helix axis is also drawn, for convenience. Note that atom 0 - 6 mediates both intra- and inter-double helix hydrogen bonds.
RENGASWAMI CHANDRASEKARAN
342
6
FIG. 10. (continued)-(b) A projection of the unit cell contents along the c-axis, with a down and b across the page. A water molecule (crossed circle) per trisaccharide bridges three surrounding helices.
structure has been refined against the observed X-ray intensities, which include 34 fiber data and 21 powder peaks extracted from the one-dimensional 28 scan. The corresponding final R-values are 0.27 and 0.21. The electron-diffraction data were not used in the refinement. Because the A-amylose double helix has a trisaccharide repeat, three sets of and x) listed in Table I11 define the conformation of the four angles (7,4, chain in which all the glucose residues adopt identical 4C, ring geometries. There is no intrachain hydrogen bonding, but the gg orientations of the hydroxymethyl groups result in interchain hydrogen bonds between atoms 0-2 and 0-6 within the double helix, and among atoms 0-2, 0-3, and 0-6 between double helices. The one and only water molecule per maltotriose residue is also involved in hydrogen bonds with three double helices surrounding it, as shown in Fig. lob. The hydrogen bond distances range from 2.6 to 2.9 A.
+,
b. B-Amylose (9).-SimiIar material preparation as for 8, but through two stages of three days each of 80 and 100%r.h., respectively, at room temperature,
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
343
and a third stage of annealing in hot water at 9OoC for one hour produces B-amylose from amylose triacetate fibers.” X-Ray diffraction patterns correspond to a hexagonal unit cell. As with their results on A-amyl0se,8~the authors proposed an antiparallel packing of two &fold, right-handed, half-staggered, parallel double helices passing through (%%70)and (%%O). Half-a-turn per double helix and 36 water molecules were located in the unit cell. Again, as in the case of A-amylose, the antiparallel packing has faced severe criticisms from the point of view of starch biosynthesis.88*8Y Using the same X-ray data of Wu and Sarko,8s Imberty and Ptrez” re-investigated B-amylose. The corrected model essentially resembles the revised A-amylose structure16 just described, but the packing arrangement differs. The B-amylose chain is described in terms of a maltose repeating unit. The pitch of the half-staggered, parallel, 6-fold, left-handed double helix is 20.8 A. The final Rvalue after refinement against 34 reflections is 0.15. Two sets of (7,4, $, and listed in Table 111, define the disaccharide conformation. As Fig. 1 l a illustrates, hydrogen bonds absent within each chain, but present between chains connect-
x),
b FIG. I 1.-Parallel packing arrangement of 6-fold, B-amylose (9) molecules. ((1) Stereo side view of slightly less than 2 turns of a pair of double helices 10.7 8, apart along the long diagonal of the ahplane. The two strands in each helix are distinguished by open and filled bonds, and the helix axis is also drawn, for convenience. Notice that atom 0-6 mediates both intra- and inter-double helix hydrogen bonds.
344
RENGASWAMI CHANDRASEKARAN
B
FIG. 1 1 . (contitiued)--(b) A view of the unit-cell contents down the c-axis and remaining four helices, which surround a cluster of 6 water molecules (crossed circles) per disaccharide in the middle.
ing atoms 0 - 2 and 0-6, stabilize the double helix. Two double helices of the same polarity pass through (%!40)and (%%O) of the unit cell. Six water molecules per disaccharide repeat, or 36 per cell, have been located. The crystalline lattice corresponds to space group P6, so that the two helices in the cell are related by a crystallographic 2 , axis parallel to c passing through (%!hO). It displays a hexagonal network of amylose helices, as shown in Fig. 1Ib. The channel in the middle, almost as wide (10 A) as the helix itself, is filled with water molecules that are hydrogen bonded to the surrounding helices. If another amylose double helix were to replace these ordered water molecules, the resulting packing arrangement would mimic that of A-amylose, shown in Fig. lob. With regard to molecular morphology, whether it is A- or B-amylose, there is no room for a water or similar molecule to enter the cavity in the interior of the
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
345
helix. The origin of this stems from the fact that of -60", in conjunction with a large of roughly 3.5 A, produces a narrow and relatively extended helix. Coaxial intertwining of two such helices leads to a tight complex and low solubility, as observed. Extrapolation of the molecular structure of an a-rnaltohexaose duplex complexed with triiodide in single crystals leads to a left-handed, 8-fold, antiparallel double-helix for amylose.gOThe pitch of this idealized helix is 18.6 A, so h is only 2.33 A. Although this model is no contender to the fiber data, in terms of biosynthesis, it is doubtful that the native amylose helix favors antiparallel chains.
c. V-Amylose (lo).-A family of 6-fold, left-handed, single helices with very low h values (around 1.35 A) are observed, under suitable experimental conditions, when amylose fibers are formed from solution in Me,S0,28 iodine?' or butano19*in anhydrous, hydrous, or intermediate states. The structure of anhydrous V-arnyloseZ8(lo), shown in Fig. 12a, is chosen to represent the entire family. The main-chain conformation angles, 4 = 115" and = -131", are up to 30" away from those in A- and B-amylose, and the bond angle at the bridge oxygen atom is 120". The hydroxyl group has the g t orientation. The helix is stabilized by intrachain 3-OH...0-2 (2.8 A) and 6-OH...0-3 (2.9 A) hydrogen bonds, which link adjacent residues and turns, respectively. The two helices in the orthorhombic unit cell are antiparallel and connected by intermolecular 2-0H.. .O-2 (2.9- A) hydrogen bonds (not shown). An axial projection of the unit-cell contents is shown in Fig. 12b. Variations among the known V-amylose structures are only marginal. The inner diameter (4.5 A) of the shallow helix is large enough to accommodate water and molecules of similar size easily. De-
+
A
FIG. 12.-Packing arrangement of shallow, 6-fold, V-amylose (10) helices. (a) Stereo view of two unit cells approximately normal to the be-plane. The helix at the center (filled bonds) is antiparallel to the two helices at the comers in the hack (open bonds). Intrachain hydrogen bonds (3-OH...0-2 and 6-OH ' .' 0 - 3 ) are shown in thin lines.
346
RENGASWAMI CHANDRASEKARAN
FIG.12. (conrinued)-(h) A c-axis projection of the unit cell shows that water molecules (crossed circles), 3 per monosaccharide, inside and between helices, are involved in the stability of the helices.
pending on the complexing agent or solvent used, the full range of flexibility available to the hydroxymethyl group is exploited. As a consequence, the packing arrangements of helices display some changes among the various examples studied to date.
d. KOH - Amylose complex (1 1).- An extended six-fold, left-handed, helix with h = 3.74 8, is almost unique for amylose complexed with KOH,29 and its morphology is far from the shallow structure of 10. The repeating motif is compatible with a trisaccharide moiety in the final model, similar to that in Aamylose (8). Each trisaccharide is associated with a KOH ion pair and three water molecules. The main-chain conformation angles (4 and 6)for the three saccharides are minimally afar from 93 and - 150", respectively, the bond angle at the bridge oxygen remaining near 115". Thus, the amylose chain in the KOH complex (Fig. 13a) is virtually superposable on either chain in A- or B-amylose double helix. The orientations of the three hydroxymethyl groups are two gg and one tg. A potassium ion is involved in connecting two helices-each of which provides two oxygen atoms as ligands. The close packing of helices in an orthorhombic lattice, further stabilized by a water molecule per monosaccharide, is shown in Fig. 13b.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
341
e. Amylose Derivatives.-Several amylose derivatives, in which all three potential hydroxyl groups are substituted, are of some interest, They include amylose triacetate,”’ tri-O-methylamylose,y4 tri-O-ethylamyl~se,’~and their complexesY5with solvents. All of them generally conform to d-fold, left-handed, helices, whose h values vary from 3.75 to 4.05 A. Of necessity, no intrachain hydrogen bonds are possible in these helices and crystalline packings are dictated by van der Waals forces alone. The structure of tri-0-ethylamylose (12) (h = 3.87 A) is reviewed as an example in this category. Its main-chain conformation angles are = 64” and = - I62”, and the bond angle at the bridge
+
+
FIG. 13.-Packing arrangement of extended, 6-fold, KOH-amylose (11) helices. (a) Stereo view of two unit cells approximately normal to the bc-plane. The helix (filled bonds) at the center is antiparallel to the two helices (open bonds) at the comers in the back. Potassium ions (crossed circles) have water molecules (open circles) and hydroxyl groups from amylose helices as ligands.
348
RENGASWAMI CHANDRASEKARAN
FIG.13. (rontinued)--(b) A c-axis projection of the unit cell shows that the amylose helices are packed tightly, aided by ions and water molecules.
oxygen atom is 122". Although x is -94", all three ethyl groups adopt roughly extended conformations. This can be visualized from Fig. 14a, which also shows that the orthorhombic unit cell accommodates two antiparallel helices. The interdigitation of the substituents from neighboring helices is an interesting observation in Fig. 14b.
6. Pectin Pectin belongs to a family of plant polysaccharides in which the polymer backbone consists of (1+4)-linked a-D-galacturonic acid repeating-units. Often, (1+2)-linked a-L-rhamnose residues interrupt the regular polygalacturonate sequence. The high viscosity and gelling properties of pectins are exploited by the food and pharmaceutical industries. X-Ray studies on sodium pectate, calcium pectate, pectic acid, and pectinic acid (methyl ester of pectic acid) have disclosed their structural details.
a. Sodium Pectate (13).-The X-ray diffraction pattern of sodium pectate" shows that the polymer forms a 3-fold helix of pitch 13.36 A, as is evident from meridional reflections on the third and sixth layer lines (Fig. 15). The 1,4-diaxial links, coupled with the 4C, chair conformation for the galacturonate residue, generate a right-handed helix with h = 4.45 A providing a better fit with the
FIG. 14.-Antiparallel packing arrangement of extended, 4-fold. 2,3,6-tri-O-ethylamylose (12) helices. la) Stereo view of two unit cells approximately normal to the bc-plane. The helix at the center (filled bonds) is antiparallel to the two helices (open bonds) at the comers in the back. There is no intra- or inter-chain hydrogen bond, and only van der Waals forces stabilize the helices. ( 6 )A c-axis projection of the unit cell shows that the ethyl groups extend into the medium in radial directions.
RENGASWAMI CHANDRASEKARAN
350
FIG.15.-X-ray diffraction pattern from a polycrystalline and well-oriented fiber of sodium pectate (13).diagnostic of 3-fold helix symmetry.
X-ray data (26 reflections) than a competing left-handed helix. The space group is P2, and the screw axis is parallel to the h-axis. The final model (R = 0.23) has conformation angles = 80" and IJJ = 90" and the bond angle at the bridge oxygen atom is 116.5'. The three residues per turn have slightly different carboxylate group orientations in the vicinity of 100" (Table 111). Each monosaccharide is associated with one sodium ion and two water molecules. The helix is stabilized by intrachain 2-OH.. . O-6 1 hydrogen bond (2.8 A) across each bridge oxygen atom. Neighboring antiparallel helices in the two-chain unit cell, separated by 8.4 A, are bridged by sodium ions located around the carboxylate groups and water molecules. These features are illustrated in Fig. 16.
+
b. Pectic Acid (14).-According to the X-ray study" on the acid form, pectic acid retains the same type of helical structure and same pitch as sodium pectate (13). Because of the absence of ions in this case, however, the inter-helical association is directly through 3-OH...0-62(2.8 A) and 61-OH...0-61 (2.8 A) hydrogen bonds (Fig. 17a). The modified packing arrangement (Fig. 17b) is reflected by altered lateral dimensions of the rectangular cell (Table I). Water molecules were not located in this study.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
35 1
B
0 0
0 0
FIG.16.-Antiparallel packing arrangement of 3-fold sodium pectate (13)helices. (a) Stereo view of two unit cells roughly normal to the bc-plane. The helix at the center (open bonds) is antiparallel to the two in the front (filled bonds). Intrdchain hydrogen bonds stabilize each helix. Sodium ions (crossed circles) and water molecules (open circles) connect adjacent helices. ( b )A view of the unitcell contents down the c-axis highlights the ions and water molecules located between the helices.
FIG. 17.-Antiparallel packing arrangement of 3-fold pectic acid (14) helices. ( a ) Stereo view of two unit cells roughly normal to the bc-plane. The helix at the center (open bonds) is antiparallel to the two in the front (filled bonds). Intrachain hydrogen bonds stabilize each helix. Association of helices is through direct hydrogen bonds involving the carboxyl groups. (h) A view of the unit-cell contents down the c-axis highlights the interactions between the three helices near the bottom.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
353
c. Calcium Pectate and Pectinic Acid.-Preliminary X-ray analysisy6 of calcium pectate is also in support of a molecular structure and packing arrangement as observed for pectic acid, with the only difference that the interchain 6 1-OH.. .O-6 1 hydrogen bond is replaced by an 0-6 1 .. .Ca2+... O-61 interaction. Methylation of the carboxyl group converts pectic acid to pectinic acid, and its gelling properties depend on the degree of methylation. These authors have speculated a hexagonal packing arrangement for pectinic acid that consists of a column of methyl (hydrophobic) groups trapped within a triad of %fold polymer helices.
7. Alginic Acid Alginic acid constitutes one of the structural polysaccharides of marine brown algae and some bacteria. The (1+4)-linked polymer contains blocks of p-D-mannuronic acid (ManA) and blocks of a-L-guluronic acid (GulA). The composition and block lengths are species dependent. For example, the sample from Fucus or Asophyllum species is 97% poly(mannuronic acid) and that from Lamineria hyperhorea is rich in poly(gu1uronic acid).3’ Alginic acid is useful to the food industries because of its cation-dependent gelling properties. Because GuiA and ManA adopt 4C, and ‘C, chair conformations, respectively, the morphologies of the two polymers are quite unrelated.
a. Poly(P-D-Mannuronic Acid) (15).-The X-ray diffraction data3* recorded from a bundle of fibers prepared from Fucus vesiculosius are reminiscent of those from mannan I (5). The authors used polarized infrared spectra as an aid to structure determination. The molecule is a ribbon-like 2-fold helix with features characteristic of cellulose and mannan-especially the 3-OH .. . 0 - 5 hydrogen bond (2.7 A). The two helices positioned at (‘AOO) and (%%O) in the orthorhombic unit cell are antiparallel and related by the space group symmetry. One of the carboxylate oxygen atoms is hydrogen bonded to atom 0 - 3 of a neighboring chain of the same polarity, separated by the h-axis. The antiparallel chains are connected by 2-OH. . . 0 - 5 hydrogen bonds (3.0 A). These features are shown in Fig. 18a. The c-axis projection (Fig. 18b) shows that the sugar rings are oriented roughly parallel to the bc-plane. b. Poly(a-L-Guluronic Acid) (16).-The structure of 16 is also derived from a joint analysis of X-ray diffraction data and polarized infrared ~pectra.’~ The meridional reflection on the second layer line is diagnostic of a two-fold helix of pitch 8.7 A, which is 1.7 A shorter than in cellulose or mannan. Atoms 0-1 and 0 - 4 are both axial in the favored ‘C, chair conformation for guluronate residue.
354
RENGASWAMI CHANDRASEKARAN
A
FIG.18.-Antiparallel packing arrangement of 2-fold poly(ManA) (15) helices. (a) Stereo view of two unit cells roughly normal to the bc-plane. The helix at the center (filled bonds) is antiparallel to the two in the back (open bonds). Intrachain hydrogen bonds stabilize each helix. Association of helices through direct hydrogen bonds involve the carboxylate groups for parallel chains, but involve the axial hydroxyl groups for antiparallel chains. (b) A view of the unit-cell contents down the c-axis highlights the interactions between the helices.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
355
Consequently, the molecular structure is more buckled (Fig. 19a) than the familiar ribbon-like cellulose chain. The two chains in the unit cell, located at ('AOO) and (%%O), and related by space-group symmetry, are antiparallel, as shown in Fig. 19a. The helix is stabilized by 2-OH ...0-61 hydrogen bonds (2.7 A). Adjacent helices are bridged by water molecules, which are present at one per guluronate residue, via 0 - 2 . . . W . - - 0 - 3 (in the front) and 0-5...W.-.0-3 (in the back) interactions. The axial projection in Fig. 19b suggests that the sugar rings completely overlap on each other. It is considered that pairs of carboxylate groups can be connected by calcium ions. The pairwise association of helices mediated by an array of calcium ions in the middle bears certain resemblance to a Styrofoam box packed with eggs. This similarity has led to the so called eggbox modely7 to depict the junction zone implicated in the alginate gelation process.
FIG. 19.-Antiparallel packing arrangement of 2-fold poly(Gu1A) (16) helices. (a) Stereo view of two unit cells roughly normal to the bc-plane. The helix at the center (filled bonds) is antiparallel to the two in the back (open bonds). Intrachain hydrogen bonds stabilize each helix. Association of antiparallel helices involves the carboxylate groups and water molecules (crossed circles).
356
RENGASWAMl CHANDRASEKARAN
FIG.19. (continuedl--(b) A view of the unit-cell contents down the c-axis highlights the interactions between the helices via water molecules. There is almost complete overlap between the sugar rings in each helix.
v. (1-+3)-LINKEDPOLYSACCHARIDES This group of polymers listed in Table IV includes both a-and P-glucans, and xylan, all of which have monosaccharide repeating units. The galactoglucan (22) has a disaccharide repeat that involves alternating a-and P-pyranosyl configurations. Although three structures are single helices, three others are triple helices. Their morphologies and packing arrangements are quite interesting.
1. (1+3)-P-~-Glucan The extracellular microbial polysaccharide having (1+3)-linked P-D-glUCOSe as its repeating unit, commonly known as curdim, forms resilient gels from aqueous solutions when heated to about 95°C. X-Ray diffraction patterns from oriented specimensgRhave led to the identification of three distinct forms (I, 11, and 111), which represent the native specimen, the hydrated form (after annealing at 14OoC),and the dehydrated form (after annealing), respectively. Initial interpretation has supported similar triple-helical structures for all three forms, but form I is now known to exist as a single helix.'4
a. Curdlan I (17).-The most-recent X-ray re-e~amination'~ of form I reveals that, consistent with a meridional reflection on the sixth layer line, the
V
TABLEIV
P
Helical Parameters and Conformation Angles in (1 -P 3)-linked Polysaccharides No.
Polymer
C b
chz
7
116.5 104.6 110.6 106.4 120.4 118.5 116.3 115.3
18 19 20 21
Curdlan I Curdlan Il Curdlan 111 (1 +3)-p-D-Xyh (1 -P 3-c-D-Glucanh
60 60 60 60 I80
3.80 3.13 2.94 3.06 4.22
22
Galactoglucan'
180
7.95
17
4J -71 - 87
- 92 - 93 I03 102 -101 88
* 126 121 126 127 103 104 88 100
Fig.
X
-54
Table
-82
20 21
A14 A15
-
-
-
52 62 - 29
22
A16
23
A17
d
-
Note: in degrees and in 8, are the average helical parameters per chemical repeat, which is a monosaccharide in 17 to 21, but a disaccharide in 22. T is the bridge bond angle C-I-0-3-C-3. The three conformation angles are Q(O-5-C-1-0-3-C-3), +(C-I-O-3-C-3-C-4) and x(C-4-C-5-C-6-0-6). The 18 hydroxymethyl groups in one turn of the triple helix have quite different orientations. The two residues per turn are conformationally independent. 'The orientation of the acetate group is given by f~,(C-5-C-6-0-6-C-7)= 132" and O,(C-6-0-6-C-7-C-8)=-143". The orientation of the pymvate group is given by O(0-6-C-7-C-8-0-81)=-44".
s
c
358
RENGASWAMI CHANDRASEKARAN
molecular structure is a six-fold, right-handed, single helix. This is further shown to be superior to the previously proposed ~ i x - f o l dand ~ ~ seven-foldlW triple-helical models. The single helix of pitch 22.8 A,illustrated in Fig. 20a, is stabilized by 4-OH. . . 0 - 5 hydrogen bonds (3.14 A). Two helices pass through (000) and (!4!hO) of the unit cell in a parallel mode. No hydrogen bonds are formed between the helices, and the interstitial space (Fig. 20b) is reported to be filled with about 250 water molecules. The final R-value is 0.14 for 40 reflections. b. Curdlan 111 (19).-The dehydrated form 111 (19) is structurally well organized. Its X-ray analysis3' reveals that 19 crystallizes in a hexagonal cell with space group P6, and there are six glucose residues per cell. The layer line spacings are consistent with a 6-fold, parallel, triple helix whose pitch is 3c = 17.61 8, so that h is 2.94 A.A right-handed helix is superior to any alternative. The final R-value is 0.23 for 21 reflections. The triple helix shown in Fig. 21a has only 110.6' for the bond angle at the bridge oxygen atom, and it is smaller than the expected 116.5'. The core of the triple helix exhibits triads of interchain 2-0H.. . O-2 hydrogen bonds (2.72 A) occurring at successive levels separated by h. The intrachain 4-OH...0-5 distance of 3.18 8, between adjacent residues might be considered as a weak hydrogen bond. The packing of molecules in the unit cell (Fig. 21b) is facilitated by a series of strong hydrogen bonds (2.70 to 2.75 A) between neighboring triple helices involving atoms 0-4 and 0-6.
A
FIG.20.-Parallel packing arrangement of 6-fold. curdlan I (17) helices. ( a ) Stereo view of two unit cells approximately normal to the bc-plane. The helix is stabilized by intrachain 4-OH...0-5 hydrogen bonds. There are only van der Waals interactions between the helices.
POLY SACCHARIDE HELICES IN ORIENTED FIBERS
359
FIG.20. (conrinued)-(h) A c-axis projection of the unit cell shows large gaps between the helices, which are allegedly filled by 250 water molecules.
FIG.21.--Structure
of the 6-fold anhydrous curdlan 111 (19) helix. (a) Stereo view of a full turn of the parallel triple helix. The three strands are distinguished by thin bonds, open bonds, and filled bonds, respectively. In addition to intrachain hydrogen bonds, the triplex shows a triad of 2-OH...0-2 interchain hydrogen bonds around the helix axis (vertical line) at intervals of 2.94 A. (b) A c-axis projection of the unit cell contents illustrates how the 6-0H.. '0-4hydrogen bonds between triple helices stabilize the crystalline lattice.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
36 1
c. Curdlan I1 (18).-This hydrated form I1 is mildly distorted from the ordered structure of 19. An X-ray analysis3sof 18 indicates that its unit cell is also hexagonal as in 19, but its c value is 18.78 8,. This has been interpreted in terms of a triple helix whose backbone is essentially similar to that of 19, but the orientations of the 18 hydroxymethyl groups in one turn are scattered in the entire range of staggered domains. This irregularity accounts for the presence of the 18.78 8, layer line and also justifies the treatment of the structure analysis of 18 to a lower symmetry space group (Pl). The glycosidic bridge angle is 104.6”, much smaller than in 19. Six water molecules per monosaccharide were located in the unit cell between triple helices. These water molecules bridge adjacent helices through hydrogen bonds. The final R-value is 0.17 for 79 reflections. 2. (1--+3)-p-~-Xylan The cell walls in some siphoneous green algae contain the structural polysaccharide xylan (20), whose repeating unit is (1*3)-linked p-D-xylose. Structure a n a l y ~ i s ” ~ ’with ~ ’ limited X-ray data is in favor of a 6-fold, righthanded, triple helix of pitch 18.36 8, in the wet state, or 17.55 8, in the dry state, which is conformationally and morphologically similar to that of 19 (Fig. 2 1a) described earlier. The one-triple helix unit-cell is hexagonal (Table I) in the wet state. Upon dehydration, the cell shrinks by 12% laterally and 5% axially. Although the details on packing arrangement are not given in the original publication^,^^^'^' the absence of atom 0 - 6 suggests that van der Waals forces must be responsible for the lateral organization of the triple helices of 20.
3. (1+3)-a-~-Glucan Such non-cellulosic polysaccharides as (1+3)-a-~-glucan (21) provide structural stability to the cell walls in certain microorganisms, including some fungi. One of the crystalline forms of this polymer has been i n ~ e s t i g a t e d . ~ ~ The results show that the polymer forms a fully extended and relaxed, 2-fold helix of pitch 8.44 8, (Fig. 22a), which is stabilized by 2-OH-..0-4 (2.9 8,) hydrogen bonds. The two repeating units per turn have almost the same backbone conformation angles, but the hydroxymethyl groups in them differ by 10” in x. The orthorhombic unit cell accommodates four chains related by space group P2,2,2,. There is an extensive network of interchain hydrogen bonds involving all free hydroxyl groups (Fig. 22b). The sheet-like packing arrangement, analogous to those observed for cellulose and related polymers (1 to 6), is consistent with its functional property as a structural polysaccharide.
362
RENGASWAMI CHANDRASEKARAN
B
FIG.22.-Antiparallel packing arrangement of the 2-fold helices of (1-+3)-a-D-glucan (21). (a) Stereo view of two unit cells approximately normal to the nc-plane. The two chains in the back (open bonds) are antiparallel and so are the chains in the front (tilled bonds). Each helix is stabilized by 2-OH.. '0-4 hydrogen bonds across the bridge oxygen atoms. Interchain hydrogen bonds are fonned in sheets along the a direction. (h) An axial projection of the unit cell shows that the sheets in the front and back are also joined by hydrogen bonds.
4. Galactoglucan
Mutant YE-2 of Rhizobium meliloti excretes a mixture of soluble polysaccharides that include a complex succinoglycan having a branched octasaccharide repeat as well as a simple galactoglucan (22) having a linear disaccharide repeat.Io2 In contrast to the case of the succinoglycan, oriented fibers of the potassium salt of 22 have yielded good X-ray data and its three-dimensional structure has been e ~t a bl ishe d.~~ The polymer forms a two-fold helix of pitch
POLYSACCHARIDE HELICES IN ORIENTED FTBERS
363
15.89 A. The combination of (1+3)-linkage with alternating axial and equatorial orientations for the C- 1 -0-1 bonds gives rise to a sinuous right-handed twist to the polymer chain, as shown in Fig. 23a. Both the pyruvic carboxylate and actetyl groups on adjacent residues form the exterior of the helix. No intrachain hydrogen bonds are in the main chain. However, a potassium ion around the carboxylate group and three water molecules in its vicinity are bound to every disaccharide repeat in an ordered way. These guest molecules are instrumental in linking the acetate and carboxylate moieties of adjacent residues via hydrogen bonds.
A
I
FIG. 23.-(a) Stereo view of about two turns of the 2-fold helix of potassium galactoglucan (22). Each carboxylate group is bound to a potassium ion (crossed circle). The helix is stabilized by hydrogen bonds from the acetate and pyruvate groups to the main chain via water molecules (open circles).
364
RENGASWAMI CHANDRASEKARAN
FIG.23. (continued)--(h) An axial projection of the unit cell shows that the helices associate via carboxylate...potassium...water...carboxylateinteractions.
Two helices are packed antiparallel in the orthorhombic unit cell. Association of the helices occurs through a series of periodic carboxylate...potassium. . water. ..carboxylate interactions. An axial projection of the unit-cell contents (Fig. 23b) shows that the helices and guest molecules are closely packed. This is the first crystal structure of a polysaccharide in which all the guest molecules in the unit cell, consistent with the measured fiber density, have been experimentally located from difference electron-density maps. The final R-value is 0.26 for 54 reflections, of which 43 are observed, and it is based on normal scattering fa~t0rs.l~
VI. (1+4), (1'3)-LINKED
POLYSACCHARIDES
In contrast with the monotonous monosaccharide repeat and the same type of linkage in the polysaccharide structures (1 to 21) described in Sections IV and V, this section deals with rather more complex polymers (23 to 39), which are composed of disaccharide repeats. Further, combining two types of linkages enhances the formation of exotic morphologies not amenable to the former set. The sequence listed in Table I1 is referred to as -A-B- in Table V while listing
TABLE V Helical Parameters and Conformation Angles in (1 -+4), (1
No.
Polymer
ch
chs
T~
QI
23 24 25 26 30 32 33 34 35 36 31 38
L-Carrageenan" K-Carrageenan Agarose Na+ Hyaluronate I Na+ Hyaluronate 111 K+ Hyaluronate I11 Na+ Chondroitin 4.50; K+ Chondroitin 4SOi Ca2+Chondroitin 4SO; Na+ Dermatan 4SO;I Na+ Dermatan 4SO; I1 Na+ Dermatan 4SO; III*
120 120 - 120 -90 - 120 - 90 -120 -120 180 - 120 180 135
8.85 8.33 6.33 8.49 9.50 8.20 9.44 9.24 9.82 9.41 9.39 9.19
39
Keratan 6-sulfate"
180
9.45
116.5 116.5 116.5 116.5 116.5 118.8 116.5 118.2 116.5 116.5 116.5 116.5 116.5 116.5
-87 - 98 - 124 - 80 - 83 -79 - 80 -87 - 98 -87 - 98 - 103 - 103 - 102
xA 94 108 -113 -107 -135 -90 -129 -136 -174 -137 -178 -141 -141 -149
176 -178 -69 -177 39 98 -122 -66 -147 80 96 93 91 -179
+,,
3)-linked Polysaccharides
+
T~
Q2
J12
116.5 116.5 116.5 116.4 116.4 114.0 116.6 119.2 116.5 116.5 116.5 116.5 116.5 116.5
75 61 -52 -45 -66 -70 -87 -85 -79
79 81 157 106 118 117 128 137 107 120 134 103 103 125
-64 -105 -160 -160 -120
xe ...
...
...
... ...
... -91 -131 -108 110 42 -89 5 -7 18 -4 -179
Note: are average helical parameters per disaccharide repeat. 7,. $, refer to A( 1 +4)B and T ~+z,, entations of hydroxymethyl or carboxymethyl groups in residues A and B, respectively. a 0, and O2 for the sulfate group in residue B are - 140 and - 165' in 23; - 150 and 180" in 39. The two disaccharide repeats are conformationally independent.
'
8
-79 -95 -86 -113 -131 -93 -111 -155 -119 -125 -120
€I1
115 118
... __. ... .._ 163 150 118 120 124 121 124 180
O2
Fig.
Table
-159 -155
24 25 26 28 29 30
A18 A19 A20 A2 1 A22 A23
-
-
31 32
A24 A25
-
-
-
-
33
A26
... ... ...
... 103 112 138 65 140 96 111 180
to B(1+ 3)A linkage. xA and xBare the ori-
366
RENGASWAMI CHANDRASEKARAN
the conformation angles. The structures include carrageenans and agarose, which are useful as gelling agents and they form double helices. Hyaluronan, chondroitin, dermatan, and keratan are members of the glycosaminoglycan family, commonly found in connective tissues; except for hyaluronan, they are sulfated. Their structures constitute a spectrum of single helices and one double helix. The packing arrangements in all cases are generally controlled by cations and water molecules. Although heparan sulfate and heparin are biologically relevant blood anticoagulant polysaccharides belonging to this family, their molecular morphologies are either too sketchy to describe or are yet to be unraveled.
1. Carrageenans Carrageenans belong to a family of gel-forming sulfated polysaccharides found in the marine red algae Rhodophyceae. Two principal members, known as L- and K-carrageenan, differ chemically in their degree of sulfation. In the case of K-carrageenan, the 3,6-anhydrogalactose residue B is not sulfated. Both polymers form thermally reversible gels that exhibit substantial differences in their physical properties. For example, L-carrageenan forms very clear and elastic gels that neither exhibit syneresis nor undergo hysteresis effects. In contrast, K-carrageenan gels are hazy and brittle, and exhibit syneresis, as well as hysteresis effects. Their molecular structures are not the same.
a. L-Carrageenan (23).-Using X-ray diffraction data from polycrystalline and well-oriented fibers of Ca2+ 6-carrageenan, that have meridional reflections on the third and sixth layer lines, Arnott et al.,O have shown that the polymer forms a three-fold, right-handed, parallel, half-staggered, double helix. The pitch is 2c = 26.56 A. The double helix, shown in Fig. 24a, incorporates the favored ,C, and IC, chair geometries in residues A and B, respectively, and contains both sulfate groups on its periphery. The two glycosidic bridge angles are 116.5". The main-chain conformation angles (Table V) defining the backbone geometry correspond to low-energy domains of the corresponding disaccharide fragments. The galactose residues are connected by 6 interchain 6-OH... 0 - 2 hydrogen bonds (2.7 A) per pitch length. The trigonal unit-cell accommodates only one double helix. A packing arrangement with up- and down-pointing molecules distributed randomly at each cell comer, similar to that shown in Fig. 24b, explains the presence of both Bragg reflections and layerline streaks. The 2-sulfate groups on the anhydrogalactose residues of adjacent double helices, linked through direct SO, -. ..Ca2+.. SO,- interactions, are considered to be responsible for the aggregation of polymer chains during gel formation. +
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
361
b. K-Carrageenan (24).-Fibers prepared from the potassium salt of Kcarrageenan are somewhat oriented, but substantially less crystalline, than those of L-carrageenan (23). Consequently, the diffraction pattern shows only continuous intensities on layer lines.41Notable features are that the first layer-line spacing is 25 A, which is roughly twice that of iota carrageenan, and meridional intensities are present on the sixth and ninth layer lines. On the basis of some similarity in overall intensity distribution with that of iota carrageenan, and as a reasonable fit with the observed X-ray intensities, a double-helical model has emerged for K-carrageenan. As shown in Fig. 25, the two chains in the 3-fold,
FIG.24.-(a) Stereo view of slightly over a turn of the 3-fold double helix of t-carrageenan (23). The two chains are distinguished by open and filled bonds for clarity. The vertical line is the helix axis. Six interchain hydrogen bonds per turn among the galactose residues stabilize the double helix. The sulfate groups lined up near the periphery are crucial for intermolecular interactions.
RENGASWAMI CHANDRASEKARAN
368
6
FIG.24. (ronrinued)--(h) An axial projection of the unit cell contents. The double helix at each corner can be either “up-” or “down-pointing:’ in terms of the X-ray data. All are, however, “up” in this diagram so that a calcium ion (crossed circle) is connected to the sulfate groups in three surrounding helices.
right-handed, parallel, double helix are offset from the half-staggered position by 1.1 A along, and 28” about, the common helix axis. Because of this offset, the 25 A layer line is not extinguished in the diffraction pattern; second, there are only half the number of interchain 6-OH...0-2 (2.5 A) hydrogen bonds between the galactose residues. The main-chain conformation angles are subtly different from those in iota carrageenan. Details of the interactions among helices and the structural role of potassium ions remain unknown. Consistent with their chemical differences, the molecular structures of L- and K-carrageenans are not identical. A shorter pitch and an offset positioning of the two chains in the kappa helix is compatible with the lack of sulfate group on every 3,6-anhydrogalactose residue. The variations in molecular structures mirror the types of junction zones formed by these polymers and relate to the observed gelation properties. 2. Agarose Agarose (25) is an excellent gel-forming polysaccharide belonging to a family of red seaweeds Rhodophyceae. The fundamental difference in covalent structure between agarose and carrageenan is in the inversion of the 3,6-anhydrogalactose residues from D to L. As in the case of K-carrageenan, agarose fibers are oriented
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
369
U
FIG. 25.-Stereo view of about a turn of the 3-fold double helix of K-carrageenan (24). The two chains are distinguished by open and tilled bonds for clarity. The vertical line is the helix axis. Only three interchain hydrogen bonds per turn among the galactose residues stabilize the helix. The sulfate groups near the periphery are crucial for intermolecular interactions.
and non-crystalline. Therefore, the diffraction patterns of agarose consist of only continuous intensities on layer lines. The first layer-line spacing is 9.5 A and meridional intensity is on the third layer line. With both monosaccharides in the favored 4C, chair conformations, Amott et ~ 1 . ~produced ’ a 3-fold, left-handed, half-staggered, parallel, double helix of pitch 2c = 19.0 8, as the best choice. Because of the absence of sulfate groups, the agarose helix (Fig. 26) is much shorter than the carrageenan helices. The conformation angles (Table V) are unrelated to the carrageenans for chemical reasons. Surprisingly, there are no hydrogen bonds and the double helix is stabilized only by van der Waals forces. The central cavity, however, might hold water molecules, which can mediate interchain hydrogen bonds with oxygen atoms 0 - 2 A and 0-5B positioned in the interior.
370
RENGASWAMI CHANDRASEKARAN
FIG.26.-Stereo view of over one turn of the 3-fold double helix of agarose (25). The two chains are distinguished by open and filled bonds for clarity. The vertical line is the helix axis. Only van der Waals forces stabilize the double helix.
Agarose films dried at about 100°C produce sharper diffraction patterns, which have been interpretedlo3in terms of extended single helices, in which h ranges from 8.9 to 9.7 A. However, these models are incompatible with chiroptical data,IM which indicate only double helices akin to the original X-ray strucme4*or similar modelslo5derived from energy minimization.
3. Hyaluronan Hyaluronan, also known as hyaluronic acid, is an unsulfated glycosaminoglycan found in mammalian connective tissues, where it forms the central core of the proteoglycan aggregate. Extensive X-ray investigations on polycrystalline and well-oriented fibers prepared from sodium, potassium, and calcium salts reveal that hyaluronate helices are polymorphic. At least seven allomorphs (26 to 32) are characterized under three major categories. All are 4-fold and 3-fold, left-handed, helices, incorporating 4C, pyranose ring conformations. Under the influence of cations, humidity, or both, the 4-fold helix is tolerant to stretching
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
37 1
and contracting, as is evident from its axial rise per disaccharide ranging from 9.5 to 8.5 A, but the 3-fold helix is limited to the fully stretched value of 9.5 A. In the presence of potassium ions, a DNA-like antiparallel double helix is also possible. In every case, one or more intrachain hydrogen bonds per disaccharide repeat contribute to helix stability. Although the repeat has the potential to participate in up to four hydrogen bonds (marked 1, 2, 3, and 4 in Fig. 27) within the chain, no allomorph displays more than two of them because of conformational restrictions. Such versatility in morphology is commensurate with the
FIG.27.-Schematic drawing of a hyaluronan segment. Each disaccharide repeat has the potential to participate in four hydrogen bonds, 1 and 2 across the (1+4), and 3 and 4 across the (1-+3)-linkage.
312
RENGASWAMI CHANDRASEKARAN
known biological functions of hyaluronan in connective tissue, cartilage, umbilical cord, cornea, and the like and is unsurpassed by any other member in the glycosaminoglycan family, The variations in molecular structures and crystal packings are illustrated with an example from each of the three categories.
a. 4-Fold Helix.-There are four allomorphs in this group. Two of them are strict 4-fold helices with -A-B- repeats. The other two are relaxed or mildly perturbed from this symmetry and hence described by 2-fold helices with -AI-B 1 -A2-B2- repeats. Relaxation occurs when monovalent ions are used. The structure of the 4-fold sodium form is fully described first. Subsequently, the essential features in the remaining three allomorphs are compared and contrasted with the first. (i) Sodium Hyaluronate I (26).-The fiber-diffraction pattern from sodium hyaluronate at 0% r.h. shows meridional reflections on the 4n layer lines, indicating 4-fold helix symmetry:’ This corresponds to the dry state. The best molecular model compatible with the X-ray data is a left-handed helix of pitch 33.94 A, shown in Fig. 28a. The helix is stabilized by hydrogen bonds 2 and 3
FIG.28.-Antipaallel packing arrangement of 4-fold helices of sodium hyaluronate (26). (a) Stereo view of a unit cell approximatelynormal to the hc-plane. The two comer chains in the front (filled bonds) are linked directly by hydrogen bonds. The chain at the center (open bonds) interacts with the comer chains via sodium ions (crosses circles) and hydrogen bonds.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
U
373
W
FIG.28. (conrinuedi--(hl An axial projection of the unit cell shows that the close packing of the chains is more prominent along the diagonals than along the edges.
(see Fig. 27). In the GlcNAc residue, the orientation of the hydroxymethyl group is gt. The carboxylate group orientation in the glucuronate residue is xB= -91". Consistent with space group symmetry P4,2,2, two helices pass through (000) and (hh0)of the unit cell in an antiparallel mode (Fig. 28b). The guest molecule is only a sodium ion per disaccharide near the carboxylate group; it has a roughly octahedral coordination to six ligands from three surrounding helices. If antiparallel helices are linked by carboxylate . ..sodium. ..hydroxymethyl interactions, as well as 3-0H... 0-62 (2.59 A) hydrogen bonds, two others, 2-OH. . 0 - 6 (2.37 A) and 6-OH. . . 0 - 7 (2.79 A), connect neighboring helices of the same polarity. Such direct interactions in the absence of water molecules produce a tight packing arrangement.
(ii) Sodium Hyaluronate I1 (27).-When the fibers of 26 are hydrated (such as at 75% r.h.), the square base of the tetragonal cell breathes uniaxially (along a) to become an orthorhombic unit cell."3 In this relaxed state, termed as 27, the
374
RENGASWAMI CHANDRASEKARAN
helix symmetry drops from 4, to 2 , so that the new repeating unit consists of two disaccharides that are minor conformational variants of 26. Although the maximum departure is only 14" in $, IJJ values, large rotations of about 67 and 80" occurring in the orientations of the two acetamido groups, and almost 60" for one of the carboxylate groups, are sharp indicators that the four water molecules located per tetrasaccharide repeat do perturb the rigidity of side groups. Yet, there is no change in intrachain hydrogen-bonding scheme, relative to the 4fold structure 26, but some old interchain hydrogen bonds are lost in place of new, because of the expansion of a. This structure still possesses one sodium ion near every carboxylate group. The octahedral coordination schemes for the two ions in the tetrasaccharide repeat are not the same, but both of them utilize one or two water molecules as ligands.
(iii) Potassium Hyaluronate I (28).-An extended 4-fold helix prevails at 85% r.h., giving rise to a second tetragonal form (28) when potassium replaces s0dium.4~Because of the 1 1 % longitudinal stretching relative to the sodium helix 26, only one intrahelical hydrogen bond 3 (see Fig. 27) is preserved in 28. The molecular and crystal structures show many similarities and few differences among the two tetragonal forms. For example, the main-chain conformation angles undergo only modest (<13") changes and the carboxylate group is just 5" away; however, the hydroxymethyl and acetamido groups differ by 31 and 56", respectively. The packing arrangement (space group P4,2,2), with one potassium ion and two water molecules per disaccharide repeat, is analogous to that observed for the sodium structure (26). The potassium coordination includes one water molecule and two ligands from each of three surrounding helices.
(iv) Potassium Hyaluronate I1 (29). -Fibers of potassium hyaluronate also give rise to another diffraction pattern showing meridional reflections on even layer lines and corresponding to an orthorhombic unit cell.45In this relaxed state (29), the helix symmetry is 2,, or 4, perturbed, so adjacent disaccharides within a tetrasaccharide repeat are no longer identical and is 8.85 A, 0.35 A longer than in 26. However, both disaccharides are virtually indistinguishable, either among themselves or with the high symmetry form, except for the conformations of a carboxylate and an acetamido group, which are 26 and 35", respectively, further rotated from 26. Despite relaxation, hydrogen bonds 3 and 4 are present in every disaccharide, but only one of the two acetamido groups is able to make hydrogen bond 2 within the helix. Each tetrasaccharide is associated with two potassium ions near the carboxylate groups and two water molecules. Two helices pass through (000) and (IhIhO) of the unit cell in antiparallel fashion, and they are rotated by roughly 90" about their helix axes, relative to that in the orthorhombic form (27). Consequently, the interactions between helices are significantly contrasted in the two structures. The seven coordination for potas-
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
315
sium is facilitated by a carboxylate oxygen atom, a water molecule, and five remaining ligands from three surrounding helices. Mitra et have also re-refined the structures of the regular (26) and relaxed 4-fold sodium hyaluronate (27) helices for direct comparison with their own analysis of the relaxed 4-fold helix of potassium hyaluronate (29). Within experimental error, their final models strongly support the original results, which have been described here.
b. 3-Fold Helix.-The two allomorphs in this group correspond to sodium and calcium as cations. Although the molecular structures are analogous, the packing arrangements are not. The structural details of the sodium form are described first and using them as reference, it is simple to follow the geometry of the calcium allomorph. (i) Sodium Hyaluronate 111 (30).-Some of the fibers prepared at 40°C and 90% r.h. produce diffraction patterns showing meridional reflections on 3n layer lines, implying 3-fold helix symmetry.46The reflections can be indexed on a trigonal unit cell. Structure analysis has led to a left-handed, 3-fold helix with fully extended 9.5 8, for h as the best model. Its morphology is shown in Fig. 29a.
FIG. 29.-Antiparallel packing arrangement of 3-fold helices of sodium hyaluronate (30). (a)Stereo view of a unit cell approximately normal to the long diagonal of the ah-plane. The two chains, drawn in open and filled bonds for distinction, are not only linked by hydrogen bonds, but are also connected by sodium ions (crossed circles).
RENGASWAMI CHANDRASEKARAN
376
B
FIG.29. (contbiued)--(h) An axial projection of the unit cell shows that there is sufficient room for guest molecules in the middle along the short diagonal, such as the water molecule (open circle) bridging both chains.
An important characteristic of this helix is that it is stabilized by hydrogen bonds 1 and 3 within the main chain, the latter being a common feature in all of the allomorphs. The acetamido group does not participate in intrachain hydrogen bonding. The largest departure from the corresponding conformation angles in 26 is 28" for JI1. The orientation of the hydroxymethyl group is gg. The carboxylate group orientation is xB= - 131". Two helices passing through ('%%O) and (%%O) of the trigonal cell are aligned antiparallel, consistent with space group P3,21 (Fig. 29b). One sodium ion (near the carboxylate group) and about 3.5 water molecules are located for a disaccharide repeat. The sodium ion has a total of six ligands in roughly octahedral coordinaiion; these include carboxylate oxygen atom 0-61 from one helix, atoms 0 - 2 and 0-7 from an antiparallel helix, and three water molecules. Thus, a pair of antiparallel helices associate via carboxylate ...sodium.. . O-2(glucuronate)/O-7(carbonyl)interactions. This is further stabilized by a 6-OH...0-3 (2.72 A) interchain hydrogen bond. The remaining % water molecule, occupying a special position on a crystallographic dyad, plays a divalent cation-like role in the packing arrangement by creating a direct carboxylate.. .water.. .carboxylate link between neighboring helices.
(ii) Calcium Hyaluronate (31).-X-Ray diffraction patterns of calcium hyaluronate at 75% r.h. and higher are consistent with 3-fold helix symmetry as in 30, but the trigonal unit-cell dimensions are unusually large:' There are six
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
317
helices of 31 per cell and the space group is P3,12. To satisfy this, the helix symmetry has been relaxed so that three disacchandes in one turn constitute the repeating unit. Because of this additional flexibility, both the main chain and side groups experience substantial excursions from the regular helix of 30. The largest departure in a main-chain conformation angle is 38" and two of the three hydroxymethyl group orientations correspond to near-eclipsed values. However, both hydrogen bonds 1 and 3 prevail and provide helix stability. Interactions between the six (three up- and three down-pointing) helices in the unit cell are facilitated by calcium ions (which occupy special positions on crystallographic dyads and hence are shared by two helices) in the form of carboxylate...calciurn.. .carboxylate interactions. The coordination for the ion is completed by three pairs of dyadically related water molecules. The surroundings of the three calcium ions per turn are similar. In essence, the molecular morphologies are nearly the same, but the intermolecular interactions in 31 are much more complex than in 30.
c. Potassium Hyaluronate I11 (32).-Polycrystalline and well-oriented fibers of potassium hyaluronate prepared at low pH (3.0 to 4.0) correspond to a hemi- or fully protonated state of the polymer. The initial X-ray investigationim correctly interpreted the X-ray data in terms of an antiparallel, left-handed, 4-fold double helix with a contracted pitch of 32.8 A. In conformity with systematic h + k + 1 = odd absences, the space group of this tetragonal form was chosen as 14,22. Two double helices, related by a crystallographic dyad, pass through (1/41/40and ) (%%O) per cell. However, Sheehan et ~ 1 . acknowledged ' ~ certain deficiencies in their proposal. First, their model does not resemble, even remotely, the left-handed 4-fold single helix43of 26. Second, it is unstable because of the lack of intra- or inter-chain hydrogen bonds. A careful re-examination4' of the published X-ray data"' has produced an excellent double helix (Fig. 30a), in which the chain is closely related to 26. Each chain is extensively hydrogen bonded across the bridge oxygen atoms. This is the only allomorph to exhibit three hydrogen bonds, 2, 3, and 4, per disaccharide repeat. The double helix is stabilized by interchain carboxyl .. .carboxylate hydrogen bonds and carboxyl .. .water. ..water.. .carboxyl bridges. A potassium ion and a water molecule per disaccharide repeat have been located. A view of the crystal structure projected along the c-axis is shown in Fig. 30b. It is interesting that the cations are regularly placed between the duplexes and not within. If they are not involved in close interactions with the polymer chains, it might seem that they are redundant for the stability and survival of the double helix. The association of the double helices is mediated by a series of 6-OH...0-7 (2.72 A) hydrogen bonds, which are made possible because of the gg hydroxymethyl orientation vis-8-vis gt in 26.
378
FIG.30.-Packing
RENGASWAMI CHANDRASEKARAN
arrangement of 4-fold antiparallel double helices of potassium hyaluronate (32).
( a ) Stereo view of a unit cell approximately normal to the line of separation of the two helices. The
two chains in each duplex, drawn in open and filled bonds for distinction, are linked by not only direct hydrogen bonds, but also water bridges. Inter double-helix hydrogen bonds are mediated between hydroxymethyl and N-acetyl groups. Potassium ions (crossed circles) at special positions have only a passive role in the association of hyaluronate chains.
The foregoing structural details highlight not only the flexibility of the hyaluronate chain, but also the ease with which it is possible to make or break intrachain hydrogen bonds to stabilize a particular helix type. The variations in axial rise (8.2 to 9.5 A) and turn angle (-90 to -120") are substantial. Such structural behavior is hard to predict from conformational analysis alone because of the complexity in handling polymer helices having disaccharide, or larger, repeating units in energy calculations. 4. Chondroitin Sulfate
Chondroitin sulfates are one of the four major polysaccharides of proteoglycans. The repeating unit of chondroitin is a disaccharide similar to that in hyaluronan, except that GalNAc replaces GlcNAc. The galactose residues are 0-sulfated-either at position 4 or 6 in the native state. Systematic s t ~ d i e s ~ ~ - ~ ' on the monovalent and divalent forms show that the molecular structures of chondroitin 4-sulfate chains are left-handed helices in which h can vary from 9.3 to 9.8 A as t switches from -120" to 180". In the case of chondroitin 6-sulfate, preliminary work'07 suggests a similar trend in h coupled with three distinct val-
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
379
B
3
FIG.30. (continued)-(h) An axial projection of the unit cell shows that there is sufficient room for guest molecules between the double helices, which are contrasted by open and filled bonds.
ues for t (- 120", 135", and 180"); probable molecular models are sketched, but no structural details are given. a. Sodium Chondroitin 4-Sulfate (33) and Potassium Chondroitin 4-Sulfate (34).-XX-Ray analyses of 33 (Ref. 49) and 34 (Ref. 50) demonstrate that a lefthanded 3-fold helix, with sulfate groups in the periphery, is preserved in both cases. One cation per disaccharide and water molecules bound to adjacent helices are located in both structures. Although their trigonal unit cells (Table I) are isomorphous, their crystal-packing arrangements are not, presumably because the coordination properties of the ions are not alike. The results for 34 are presented here. The helix shown in Fig. 31a is stabilized by a 3-OH...0-5 hydrogen bond (2.74 A) across every (l*)-linkage. The sulfate groups occur on the helix periphery.
380
RENGASWAMI CHANDRASEKARAN
B
FIG.3 I. -Antiparallel
packing arrangement of 3-fold helices of potassium chondroitin 4-sulfate (34). (a) Stereo view of a unit cell approximately along the crystallographic 2-fold axis perpendicular to the helix axis. The two chains, drawn in open and filled bonds for distinction, are not only linked hydrogen bonds but also connected by potassium ions (crossed circles) and water molecules (open circles). (b) An axial projection of the unit cell shows that there is sufficient room for guest molecules in the middle along the short diagonal, especially the water molecules and the ions bridging both chains. This also highlights that the sulfate groups are farthest from the helix axis so as to protrude into neighboring unit cells.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
38 1
Related by space-group (P3,21) symmetry, two chains are packed in the unit cell in an antiparallel fashion (Fig. 31b). A potassium ion, in the midst of a pair of carboxylate groups from these two helices, nucleates carboxylate .. potassium.. .carboxylate interactions. Additional ligands to the ion from each helix include atom 0-5 of the glucuronate residue and a sulfate oxygen atom. Thus, octahedrally coordinated potassium ions and ordered water molecules (four per disaccharide) are responsible for the lateral organization and stability of the polymer chains. This arrangement leads to a spike-like channel surrounded by six polymer helices. However, the channels are larger and cylindrical in shape49in the analogous sodium salt form 33. 9
b. Calcium Chondroitin 4-Sulfate (35).-Partial or full replacement of monovalent ions with calcium, for example, produces a dramatic transition from 3-fold to 2-fold helix symmetry concomitant with a small extension in pitch. X-Ray data5' of 35, consistent with meridional reflections on even layer lines, show that the polymer forms a 2-fold helix with h = 9.82 A per disaccharide repeat. The helix, shown in Fig. 32a, is stabilized by two intrachain hydrogen bonds, 3-OH.s.0-5 (2.64 A) across (1-4) and 2-OH 9.0-7 (2.99 A) across (1+3)-linkages. The main-chain conformation angles are up to about 38O, far from the corresponding values in the 3fold helix of 34. However, the remaining conformation angles in the two cases are very similar with one exception; the hydroxymethyl group orientation is gt.
FIG.32. -Antiparallel packing arrangement of the 2-fold helices of calcium chondroitin 4-sulfate (35). (a) Stereo view of two unit cells approximately normal to the bc-plane. The two comer chains, drawn in filled bonds are hydrogen bonded to the antiparallel center chain (open bonds). Calcium ions (crossed circles), associating with sulfate and carboxylate groups and water molecules link adjacent antiparallel chains, which are also directly hydrogen bonded.
382
RENGASWAMI CHANDRASEKARAN
B
FIG.32. (continued)-(b) An axial projection of the unit cell shows that there is sufficient room for
guest molecules in the middle. Calcium ions also bridge adjacent chains of the same polarity along the o-direction (pointing down).
Optimization of the X-ray fit has led to two antiparallel helices in the unit cell passing through (000) and (0950). There are one calcium and about six water molecules per disaccharide repeat. Two parallel chains separated by 7.44 (along a ) are connected by carboxylate . .calcium .. .carboxylate interactions, as shown in the packing diagram (Fig. 32b). Other ligands to calcium include one of the sulfate oxygen atoms and five water molecules. The ability of the calcium ion to form sulfate ..calcium.. .carboxylate coordination across the ( 1+3)-linkage (Fig. 32a) appears to be crucial in the formation of the extended 2-fold helix. Each pair of antiparallel strands is connected by direct 6-0H.. .O-2 hydrogen bonds (2.77 A), as well as through two calcium ions and a water molecule.
-
5. Dermatan 4-Sulfate
Dermatan sulfates interact with collagen, elastin, and some glycoproteins to maintain structural integrity of the tissues involved. Dermatan differs from chondroitin by having a-L-iduronate instead of P-D-glucuronate residues. Detailed X-ray investigation5*of sodium dermatan 4-sulfate shows that, as in the case of chondroitin, its structure is also polymorphic. Diffraction patterns of good quality have allowed the determination of the molecular structures and packing arrangements for three distinct helical forms (36 to 38). These investigators used the same 4C, chair conformation for both residues in the disaccharide repeat
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
383
because the otherwise truns-diaxial hydroxyl groups in the IC, ring for iduronate lead to bad stereochemistry, as well as a poor X-ray fit. This action has later been questioned since the arrival of NMR spectra in support of the IC, chair or ’So skew-boat In view of this controversy, only the essential ingredients of the X-ray results” are included here. Form I (36) is a %fold, left-handed, helix of pitch 28.2 Its molecular morphology and trigonal packing-arrangement are analogous to thatSo of 34, described previously. Form I1 (37) is a 2-fold helix of pitch 18.8 whose main chain resembles that of 35, but the side chains in the two cases have different conformations, as well as packing arrangements. Form 111 (38) is rather novel in that it is a right-handed helix with 8, symmetry; its h and t values are 9.2 8, and 135”, respectively. The asymmetric motif is, however, a tetrasaccharide in which the two disaccharide repeats differ only in their side-chain conformations. There is considerable interdigitation, as two chains are packed in an antiparallel fashion in a tetragonal unit cell (space group P4,2,2). Common to all three forms is the cellulose-like 3-OH. 0-5 hydrogen bond, which provides helix ~tability.~’
A.
A,
e .
6. Keratan 6-Sulfate Like chondroitin sulfate, keratan sulfate chains constitute “bristles” attached to the protein backbone in a proteoglycan “brush” and are widely found in cartilage, nucleus pulposus, and the cornea. The degree of sulfation depends on the source. X-Ray diffraction patterns from stretched films of keratan sulfate (39) show only continuous intensities on layer lines:3 as in the case of K-carrageenan (24). Meridional reflections on even layer lines (up to 1 = 6) indicate 2-fold helix symmetry with h = 9.45 Molecular modeling has resulted in a sinuous helix (Fig. 33), stabilized by cellulose-like 3-OH. ..0-5 (2.8 hydrogen bonds across every (1-4)-linkage. The sulfate groups occur on the periphery of the helix. Although two of them near the (1-+4)-linkage are on either side of the helix axis, those near the (1+3)-linkage are on the same side. The sulfate groups and counterions are important in establishing associative interactions between helices, but the details are elusive because of the lack of suitable X-ray data.
A.
A)
VII. THEGELLAN FAMILY OF POLYSACCHARIDES This group includes a set of anionic polysaccharides secreted by unrelated bacteria. The common theme, however, is that their main chains have the same tetrasaccharide repeat. Although (high acyl) native gellan (42) and (deacylated) gellan (40,41) are linear polymers, welan (43) is a branched polymer in which a monosaccharide side chain is regularly attached to each repeat. Other members of this family, such as S-657 and rhamsan, are also branched, like welan.”’
384
RENGASWAMI CHANDRASEKARAN
FIG.33.-A stereo view of the 2-fold helix of keratan 6-sulfate (39) stabilized by intrachain hydrogen-bonds. The sulfate groups are located on the periphery of the sinuous chain.
The side chains in the latter are flexible disaccharides; on account of poor-quality diffraction patterns, their tentative molecular structures are known only from computer modeling.' I On the other hand, well-defined crystal structures are available for gellan and welan, and they can be correlated with the physical properties of the polysaccharides; the details are presented here. Their conformation angles are listed in Table VI.
'
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
385
TABLE VI Helical Parameters and ConformationAngles in the Gellan Family of Polysaccharides Parameter
40
41
42
43
- 120 18.78
- 120 18.95
1 16.5
116.1 -99 -150 - 82 I 16.6 -134 - 148 24 115.9 -141 98 62 116.4 -119 64 91
- 120 19.13 116.6 -90 - 157 -70 116.6 - 147 -157 37 115.9 - 155 96 85 117.6 - 104 90 84 116.5
- 101 - 136 -79 116.5 - 154 - 144 10 115.9 - 150
86 58 117.7 -124 88 77 -
34,35 A27
-
36 A28
-35 168 161 37 A29
1. Gellan Gellan is a gel-forming and texturing polysaccharide that is useful to the food industry. Its repeating unit (Table 11) can be denoted conveniently as -A-B-C-D-. Chemically, 75% of its backbone corresponds to that of cellulose. Its gelation properties very much depend on the amount and nature of the cation used. The polysaccharide native to Pseudomonas elodea contains 2-0-glyceryl and (50%) 6-0-acetyl substituents on residue A, and it forms only weak and rubbery gels. After removal of these substituents by alkali treatment, the polymer is called gelIan and it forms hard and brittle gels. By combining the two polymers in different ratios, and by the use of appropriate cations, gels of desired quality can be prepared.
386
RENGASWAMI CHANDRASEKARAN
a. Lithium Gellan (40).-The first investigation'" using X-ray data from polycrystalline and well-oriented fibers failed, but a later e~amination"~ succeeded in solving the three-dimensional structure of lithium gellan. Short of locating the lithium ions (which scatter X-rays very weakly), this study established that gellan forms a 3-fold, left-handed, parallel, half-staggered, double helix of pitch 56.4 8,. Interchain hydrogen bonds between the carboxylate and hydroxymethyl groups (of residue C) were shown to be crucial to helix stability. Further structural details on gellan, especially with regard to cations, are given in the following section. b. Potassium Gellan (41).-The diffraction pattern shown in Fig. 34 is from a polycrystalline and well-oriented fiber of potassium gellan." It contains nearly 40 sharp Bragg reflections up to 3 8, resolution, and they can be indexed on a trigonal unit cell (Table I). The molecular structure shown in Fig. 35a is isomorphous with that of 40. The axial rise per tetrasaccharide repeat is 18.77 A, which culminates in a fully extended conformation. Although or-L-rhamnose residues adopt the 'C, conformation, the other three have 4C, chair geometry.
FIG.34.-X-Ray diffraction pattern from a polycrystalline and the well-oriented fiber of the potassium salt of gellan (41) shows 3-fold helix symmetry.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
387
A
FIG.35.-(a) Stereo view of about a turn of the 3-fold double helix of potassium gellan (41). The two chains are drawn in open and filled bonds for distinction. Both intra- and inter-chain hydrogen bonds stabilize the helix. The vertical line is the helix axis. Octahedrally coordinated potassium ions (crossed circles) and triply hydrogen-bonded water molecules (open circles) located above the ions are integral components of the structure of 41.
RENGASWAMI CHANDRASEKARAN
388
B
FIG.35. (cuntinued)-(b) Antiparallel packing arrangement of two double helices, drawn in open and filled bonds, in the trigonal unit-cell projected along the r-axis.
The double helix is stabilized by both intra- and inter-chain hydrogen bonds. The flexibility of the chain is tempered by three hydrogen bonds per tetrasaccharide, all across the (1+4)-linkages: cellulose-like 3-OHB. ..0-5A (2.92 A), 2-OHA...0-61B (2.51 A) and 2-OHB...0-6C (2.45 A). Surprisingly, there is no hydrogen bond across the (1+3)-linkage. Between the chains is the crucial 6OHC...0-62B hydrogen bond (3.04 A) and also a potassium ion linked to both oxygen atoms of a carboxylate group. The roughly octahedral coordination for the ion is generated by oxygen atoms 0-2A, 0-61B, and 0-62B in one chain and, 0-2C and 0-6C in the other chain; a nearby water molecule (W) is the sixth ligand. This ion cage appears to be a fingerprint of any monovalent salt form of gellan. The backbone geometry is defined by the four pairs of 4, angles listed in Table VI, which also contains the side-group orientations. The ability of residue C to make an interchain hydrogen bond with a carboxylate group is especially caused by its gg hydroxymethyl orientation. The R-value for the final model is 0.18 for 5 1 reflections, of which 38 are observed. Two double helices pass through (%'no) and (%%O) per cell in antiparallel fashion (Fig. 35b). Their helix axes are laterally separated by 9.1 A. The space group is P 3 , and the unit cell holds a totai of six tetrasaccharide repeats. Each of them is closely associated with a potassium ion and four water molecules. A pair of potassium ions and another putative water molecule can mediate carboxylate.. -potassium. ..water.. .potassium. carboxylate interactions between gelIan double helices. These experimental results have been extrapolated by computer modeling, which shows that calcium gellan double helices would associate even more strongly than in the case of potassium gellan, mainly because of
+
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
389
direct carboxylate . ..calcium. ..carboxylate interactions.' l 3 This appears to be the molecular basis for the strong and brittle gelation behavior of calcium gellan-even at low ionic strength.
b. Potassium Native Gellan (42).-An X-ray studys6of 42 has revealed that the robust gellan double helix just mentioned must undergo minor conformational changes in the backbone (Table VI) to accommodate the glyceryl groups that are embedded on the helix surface, as shown in Fig. 36a. The final R-value is 0.17 for 42 reflections. Parameters defining the orientation of the glyceryl group at 0-2A are: 8,(C-3-C-2-0-2-C-9) = 42", 0,(C-2-0-2-C-9-C10) = -166", 0,(0-2-C-9-C-IO-C-11) = 78" and 0,(C-9-C-lO-C-l 1-011) = 96". Likewise for the acetate group at 06A: O5(C-5-C-6-0-6-C7) = 159" and 0,(C-6-0-6-C-7-C-8) = 73". The interchain hydrogen bond from the hydroxymethyl of residue C to the carboxylate group is preserved, despite the two terminal hydroxyl groups of the glycerate moiety occupying the same sites as the potassium ion and water molecule, respectively, in 41. This leads to minor differences in the hydrogen-bonding pattern, as compared with 41. In particular, the glyceryl group activates two new interchain hydrogenbonds, 0-6C...0-10A (2.55 8,) and 0-2B...O-I0A (3.11 8,) in each repeat and this enhances the helix stability. Further, the significant shielding of the carboxylate by the glycerate group lowers the occupancy of each potassium to half and displaces the ion itself by nearly 5.5 8, toward the reducing end. In this new position, it is loosely linked to fewer ligands, three in one chain only. These changes, coupled with an increased intermolecular separation (9.5 instead of 9.1 8, in 41), are too harsh to sustain the gellan-like carboxylate... potassium. . .water . potassium. . .carboxylate interactions, which are necessary for strong gelation. Consequently, native gellan forms only weak and rubbery gels. An axial view of the unit-cell contents (Fig. 36b) indicates that the acetyl groups sticking out of the helix protrude into neighboring unit cells.
--
2. Welan Welan is the simplest of the branched polysaccharides in the gellan family. Well known for its excellent viscosity in aqueous solution up to about 130°C (thus useful as a viscosifier in oil-well drilling), it is utilized as a cement additive in the construction of underwater pillars. X-Ray diffraction patterns from welloriented and polycrystalline fibers of calcium welan (43) provide excellent intensity data, about 80 reflections up to 2.5 A resolutions7 and they closely resemble those of gellan. The unit cell is trigonal and much larger than that of gellan. Detailed structure analysis has confirmed that welan also exists as a gellan-like double helix in which the pitch of the polysaccharide chain, 2c = 57.38 A, is 1 8, longer. The rigidity of the backbone is controlled
390
RENGASWAMI CHANDRASEKARAN
FIG.36.--(a) Stereo view of about a turn of the 3-fold double helix of native gellan (42). The two chains are drawn in open and filled bonds for distinction. Both intra- and inter-chain hydrogen bonds stabilize the helix. The vertical line is the helix axis. The potassium ions (crossed circles) have only half occupancy at each site.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
391
B
U
FIG. 36. (conrinued)-(b) Antiparallel packing arrangement of two double helices, drawn in open and filled bonds, in the trigonal unit cell, projected along the c-axis.
by a total of six intrachain hydrogen bonds in every pentasaccharide repeat. They include the cellulosic 3-OHB..-0-5A (2.46 A) as in gellan, 3-OHD-.-02C (3.06 A), and 4-OHA...0-5D (2.93 A) hydrogen bonds within the main chain. The other three are through the rhamnose/mannose side chain (denoted as E in Table VI), namely, 3-OHE...0-62B (3.04 A), 4-OHE.e.0-62B (2.58 A) and 2-OHC.. .0-5E (2.84 A). Gellan-like 6-0HC.e. 0-62B (3.08 A), and side chain-promoted 3-OHE...O-X (3.16 A) and 2-OHB...0-7A (2.49 A) are interchain hydrogen bonds. consequently, the welan double helix (Fig. 37a) is very sturdy. The four pairs of main-chain conformation angles (Table VI) are modestly different from those in gellan (41). Parameters defining the side-chain conformation are also listed in Table VI. The orientation of the acetyl substituent at 0-2A is given by BI(C-3-C-2-O-2-C-7) = -66” and 8,(C-2-0-2-C-7-07) = -21”. The R-value for the final model is 0.22 for 102 reflections, of which 76 are observed. Three welan helices pass through the unit cell, as shown in Fig. 37b. ’hvo of them, I and 11, at (%%O) and (1/3%0), are antiparallel as in gellan. A third helix, 111, at (000) is new and parallel to the first. They are equilaterally 12.0 8, apart from each other, 2.9 A farther than in 41. The unit cell contains a total of nine pentasaccharides surrounded by ordered guest molecules, which are accounted by six calcium ions and 75 water molecules. The two “up” and “down” helices interact via side chains, calcium ions, and/or water molecules. Specifically, helices I and I1 are linked only by side chain. ..side chain hydrogen bonds
392
RENGASWANI CHANDRASEKARAN
FIG.37.--(aJ Stereo view of one turn of the 3-fold double helix of welan (43). The two chains are drawn in open and filled bonds for distinction. The vertical line represents the helix axis. Both intraand inter-chain hydrogen bonds and side chains, hydrogen bonded to carboxylate groups, stabilize the double helix. Calcium ions (crossed circles) are present near the carboxylate groups, but outside the helix to make inter double-helical connections.
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
393
B
FIG.37. (continued)-(h) An axial view projected along the c-axis shows the packing arrangement of three welan double helices in the trigonal unit cell. The helix drawn in solid bonds is antiparallel to the remaining helices (open bonds). Note that calcium ions are positioned between the helices and each water molecule (large open circle) shown here is connected to all three surrounding helices. The interstitial space is occupied by several other ordered water molecules (not shown).
involving atoms 0 - 2 and 0-4. Helices I and 111, which are aligned parallel, are connected by carboxylate ...calcium. . water. ..carboxylate interactions, beside hydrogen bonds between residues A and E. Finally, I1 and 111 are held together by strong carboxylate .. . calcium.. .carboxylate interactions, in addition to sidechain.. .main-chain hydrogen bonds. These three sets of interactions might explain the behavior of welan in viscous solutions at low and high temperatures, and as cement additive, Thus, the crystal structure of welan is an excellent example for a comprehensive visualization of the constructive role of side chains to the stability of a branched polysaccharide helix.
VIII. MOREBRANCHED POLYSACCHARIDES Whether the chemical repeating motif is a simple disaccharide or up to a complex octasaccharide, the molecular morphologies of branched polysaccharides are quite intriguing. The structure of welan (43) is a pleasant surprise. Others
394
RENGASWAMI CHANDRASEKARAN
whose structures are known to varying levels include the galactomannans, composed of disaccharide repeats; xanthan (44) having penta- and the capsular polysaccharides (CPS) 46 from Escherichia coli and 47 from Rhizobium trifolii, having hexa-saccharide repeats. Among them, 46 and 47 have been successfully tackled. Their conformational parameters are listed in Table VII. That the trisaccharide side chain in xanthan is far more flexible than the monosaccharide side chain in welan is just one reason why the structure of xanthan is still elusive. Long side chains are generally susceptible to conformational fluctuations, resulting in less-ordered structures. An example of this type is a regular helical backbone distributed with conformationally nonuniform side chains. Such systems are invariably difficult to solve. TABLE VII Helical Parameters and Conformation Angles in Two Branched Polysaccharides Parameter
Escherichia coli M4146
Parameter
Rhizobium triyolii 47 ~
180 15.22 116.5 76 I06 I08 116.5 -44 117 -99 116.5 - 34 85 - 109 116.5 69 141 -169 1 16.5 91 -127 14 116.5 - 96 I20
-
39 A30
180 10.1 116.6 67 101 - 85 116.8 65 100 - 172 116.9 - 84 -135 70 116.7 101 - 94 - 65 116.6 -90 -100 79 1 16.6 -132 113 83 40 A3 1
96 $6
XF
Fig. Table ~
The orientation of the pyruvate group is given by O(0-6-C-7-C-8-0-81)
= -54".
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
395
1. Xanthan The microbial polysaccharide xanthan (44) from Xanthomonas campestris has a pentasaccharide repeat, as in welan, but it is very different because it contains a disaccharide main chain and trisaccharide side chain. Xanthan is extensively used in a variety of industries because of its unique rheological properties. For example, the very high viscosity in aqueous solution is independent of pH (from 1 to 11) and is insensitive to salt effects and temperature (from 18 to 8OOC). X-Ray diffraction patterns from xanthan show diffuse continuous intensities on layer lines and very few Bragg reflection^.^^-"^ Although the intensity data are not conducive to conducting detailed structural analysis, meridional spots on the 5n layer lines and their spacings indicate that the polymer has 5-fold helix symmetry and pitch of 47.0 A. From a knowledge of the helical parameters alone, several speculative models are proposed in these studies. They include single and double helices, parallel and antiparallel chains, left- and right-handed chiralities, and up to four chains in the unit cell. But the dilemma is that none of them provide an acceptable X-ray fit. Consequently, the molecular details of the xanthan conformation remain unknown.
2. Galactomannans Galactomannans constitute a family of plant polysaccharides containing a mannan backbone and (1+6)-linked ol-~-galactose residues as random side chains. Depending on its source, the galactose/mannose ratio can vary from 0.3 in carob, 0.6 in guaran ( 4 3 , to 0.9 in fenugreek galactomannan. Unlike mannan, and because of the side chains, galactomannans are water soluble, producing extremely viscous solutions; hence, they are used extensively as thickening agents in food products. In combination with xanthan, however, gels are formed. X-Ray fiber-diffraction patterns from any of these galactomannans resemble that of mannan, implying59 2-fold helix symmetry and a pitch of 10.3 A. Because of the three free rotations about the (1+6)-1inkage, the side chains are rather flexible. A typical regular geometry of a galactomannan helix, with a mannan-like backbone and x(C-4-C-5-C-6-0-6) = 60" and side chains on alternate mannose residues adopting the same conformation, is shown in Fig. 38. For the other two staggered domains, the relative orientations of the side chains are significantly altered, but their energies are similar. Therefore, the side chains might not preferentially adopt the same conformation in neighboring residues within the fiber. At present, the exact details of the molecular structure and subsequent packing arrangement in the orthorhombic unit cell, compatible with the observed X-ray data, have not been reported.
396
RENGASWAMI CHANDRASEKARAN
4
4
FIG. 38.-Stereo view of three turns of the 2-fold galactomannan (45) helix containing galactose side-chains on alternate mannose residues. In this conformation, the side chains are turned up toward the non-reducing end, and the backbone is stabilized by intrachain hydrogen bonds. The helix axis is represented by the vertical line.
3. Escherichia coli M41 Capsular Polysaccharide The E. coli M41 mutant CPS (46) has a complex chemical sequence. Its repeating unit is an anionic hexamer; a tetrasaccharide -A-B-C-D- in the main chain and a disaccharide -F-E- side chain, E attached to C (Table 11). Polycrystalline and oriented fibers of the sodium salt of 46 have produced good diffraction data, with reflections up to 3 A resolution. Careful X-ray analysis60 has shown that the polymer forms a left-handed, smooth and sinuous, 2-fold helix of pitch 30.4 A. As shown in Fig. 39a, the main chain is fairly close to the helix axis. A notable observation is that side chain E-F, turned up toward the non-re-
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
391
ducing end, almost shields main-chain fragment A-B-C from the surrounding medium; this leaves residue D nearly naked. The helix is stabilized by three hydrogen bonds per repeat; 0-4B.. .0-6D (2.60 A) within the main chain, 0-3E.-.0-5F (3.05A) within the side chain, and 0-3A...0-4F(2.83 A) between the two. Two antiparallel helices, related by space group symmetry, are packed in an orthorhombic unit cell (Fig. 39b). There is substantial interdigitation between the helices so that side chains and main chains are linked by hydrogen bonds, such as 0-4E...0-4D(2.73 A) and 0-4D...0-3F(2.84A) involving parallel and antiparallel strands, respectively. Plausible sites for sodium ions are near the
FIG.3 9 . 4 4 Stereo view of two turns of the left-handed, 2-fold helix of E . coli capsular polysaccharide (46) stabilized by hydrogen bonds involving both main and side chains. The vertical line represents the helix axis.
398
RENGASWAMI CHANDRASEKARAN
FIG.39. (conrinued)-(h) The antiparallel packing arrangement of helices in the orthorhombic unit cell viewed down the c-axis shows considerable interdigitation. Hydrogen bonds (not shown) connect adjacent chains.
carboxylate groups and for water molecules in the surrounding regions. However, according to the authors, it was not possible to locate these guest molecules unambiguously. The final R-value for this crystal structure is 0.26 for 68 reflections. of which 48 are observed, 4. Rhizobium trifolii Capsular Polysaccharide
A doubly branched gel-forming capsular polysaccharide (47) from Rhiz. trifolii consists of a hexamer repeat, composed of a main chain -A-B-C- and two side chains, a monosaccharide D and a disaccharide F-E, with both D and E attached to A (Table 11). Consistent with the X-ray data revealing predominantly continuous intensities on layer lines and very few Bragg reflections, the polymer forms a right-handed 2-fold helix of pitch 20.2 A. The molecular structure has been refined6' against the continuous intensities to a final R-value of 0.28. The structure, illustrated in Fig. 40a, is very sinuous and has a total of eight hydrogen bonds (four of them bifurcated) per repeat. Notably, the interior main chain is stabilized by 0-3A..-0-5C/O-5D (2.75 A) and 0-6B ---0-2C (3.00 A) hydrogen bonds. The mono- and di-saccharide side chains are in the periphery; those belonging
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
399
to successive repeats are connected by 0-2D...0-3F (3.03 A) and 0-4F..-0-2D/O-3D (3.05 A). The disaccharide side chain is itself stiffened by two hydrogen bonds, 0-6E...O-5F (2.80 A) and 0-2F...0-3E (2.52 A). The extensively hydrogen-bonded polymer chain has the appearance of a double helix. A putative packing arrangement in the monoclinic unit cell (Fig. 40b) reveals that there are no direct interactions among the main chains of adjacent helices. However, the peripheral side chains form hydrogen bonds with both main and side chains. As in the case of 46, the ordered structure of 47 supports the hypothesis that side chains often promote the formation of stable, branched polysaccharide helices.
A
FIG.40.--(a) Stereo view of two turns of the right-handed, 2-fold helix of Rhiz. hifolii capsular polysaccharide (47). The mono- and di-saccharide side chains (filled bonds) are involved in intrachain hydrogen bonds so that the molecule has the appearance of a double helix composed of an inner and outer strands. The vertical line represents the helix axis.
400
RENGASWAMI CHANDRASEKARAN
FIG.40. (conrinued)-(b) A putative packing arrangement of helices in the monoclinic unit cell viewed down the c-axis. The helices are connected by hydrogen bonds involving the side chains.
The X-ray results of 43 to 47 provide interesting information on the relationship between side chains and molecular morphology. The general interpretation is that side chains tend to interfere with helix formation, lateral organization, or both. This is consistent with the difficulties encountered in trapping 44 and 45 in their ordered states. In both cases, the cellulose-like main chains would favor extended ribbon structures and hydrogen-bonded sheets, but the side chains have to be somehow accommodated. On the other hand, the X-ray structures of 43, 46, and 47 prove that side chains in them are crucial for stabilizing the helices and for packing arrangements. The main chains in these cases favor smooth and sinuous helices. Thus, these observations highlight the dual roles of side chains to
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
40 1
molecular structure and intermolecular interactions. Because of flexibility, there are several isoenergetic conformations- especially for long side chains. A regular backbone decorated with side chains in random conformations is highly probable. It is a difficult task to predict correctly the behavior of branched polysaccharides in the solid state or in solution with currently available experimental and theoretical methods.
ACKNOWLEDGMENTS This work was supported by the Industrial Consortium of the Whistler Center for Carbohydrate Research, the Purdue Research Foundation, and the National Science Foundation (MCB-9219736). Akella Radha and Andrea Giacometti are thanked immensely for their generous help that culminated in the successful compilation of the tables and an artistic rendering of the drawings.
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IX. APPEND~X Cartesian and cylindrical polar atomic coordinates of the structural repeating unit of 31 polysaccharide helices are provided in Tables A1 to A31. Errors, if any, in the original publications have been corrected. The coordinates of hydrogen atoms are given in a majority of structures. If missing, they are not available in the references cited in Table I. Each table caption contains the structure number and polymer name assigned in Table I. Refer to Table I1 for its chemical repeating unit. Cartesian (x, y, z ) and cylindrical ( r , +, z ) coordinates are related by x = r cos+, y = I' sin+ and z is the same in both systems. Additional repeating units in a helix can be generated from (r, z ) by adding t and h to and z, respectively; I' of an atom remains the same in every repeat. Note that r and h are multiples of and given in Tables 111 to VII, where the multiplier is the number of chemical repeats used to describe the structural repeat. The multipliers are 2 for 5, 9, and 21; 3 for 8, 11, and 13; and 1 for the remaining helices. Structures 8, 9, 23,25,41, 42, and 43 are parallel double helices so that the coordinates of the second strand are (r, $, z + c). Structure 24 is also a parallel double helix, but its second strand coordinates are ( r , 9, 28, z 13.6). Structure 32 is an antiparallel double helix in which the coordinates of the second strand are ( r , -4, -z ). Structure 19 is a parallel triple helix. The coordinates of its second and third strands are ( r , 120, z ) and ( r , - 120, z ) , respectively.
+,
+
+
++
+
+
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
405
TABLE A1 Structure 1: Cellulose I
Group
Atom
x iA,
Glc
c-1
0.3487 1.4191 1.1759 -0.2433 - 1.2407 -2.6679 0.5352 2.7003 2.1084 -0.5352 -0.9406 -3.2437
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6
Y
(A,
-0.0279 0.4022 -0.2329 0.0645 -0.3331 0.0340 0.6788 0.0329 0.2903 -0.6788 0.3404 -0.9328
z
(A,
r (A)
+ i")
1.1833 2.1798 3.5396 4.0067 2.9272 3.2905 0.0000 1.6712 4.4842 5.1900 1.6919 4.1831
0.3498 1.4750 1.1987 0.2517 I .2846 2.6681 0.8644 2.7005 2.1283 0.8644 I .0003 3.3751
(A,
r (A)
4J(")
1.1833 2.1694 3.5396 4.0067 2.9272 3.2905 1.1210 0.6436 0.0000 1.6712 4.4842 5.1900 1.6919 3.6019 1.0276
0.3489 1.4744 1.1998 0.2515 1.2899 2.670 1 3.7041 4.9249 0.8582 2.7587 2.1380 0.8582 0.9966 3.1220 3.9012
-82.08 -61.57 -88.39 87.81 117.53 101.85 -61.63 -71.74 -25.57 -76.80 -69.60 154.43 82.79 75.37 - 43.45
-4.58 15.82 -11.20 165.16 - 164.97 179.27 5 I .75 0.70 7.84 - 128.25 160.11 - 163.96
TABLE A2 Structure 3: Chitin I
Group
Atom
GlcNAc
c-1 c-2 c-3 c-4 c-5 C-6 c-7 C-8 0-1 N-2 0-3 0-4 0-5 0-6 0-7
x
(A)
0.048 1 0.7020 0.0337 0.0096 -0.5963 -0.5482 1.7599 1.5435 0.7742 0.6299 0.7453 -0.7742 0.1250 0.7886 2.8322
Y (A) -0.3456 - 1.2965 -1.1993 0.2513 1.1438 2.6 132 -3.2593 -4.6768 -0.3703 -2.6858 -2.0039 0.3703 0.9887 3.0208 -2.6829
z
406
RENGASWAMI CHANDRASEKARAN
TABLE A3 Structure 5: Mannan I
Man 1
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6
H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 Man 2
c-I c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H- I H-2 H-3 H-4 H-5 H-61 H-62
-0.2127 -0.9590 -0.2826 -0.1005 0.5207 0.4832 -0.8270 -2.3123 - 1.0733 0.7779 -0.2095 1.1885 0.7607 -0.9898 0.2744 - 1.0391 1.4760 0.8337 -0.4865
0.3940 1.2049 1.0161 -0.4463 -1.2381 -2.7339 0.5067 0.8062 1.7164 -0.5751 -0.9928 -3.4 12I 0.7949 2.2252 1.8763 -0.9074 -0.8783 -3.0447 -3.0910
5.0993 6.1229 7.5076 7.8037 6.6798 6.9376 3.8639 6.1861 8.4386 8.9582 5.4794 5.9155 5.1881 5.7293 7.7231 7.9227 7.5631 7.75 14 7.1346
0.4477 1.5400 1.0547 0.4575 1.3431 2.7763 0.9699 2.4488 2.0244 0.9674 1.0147 3.6132 1.1002 2.4354 1.8963 1.3795 1.7176 3.1568 3.1291
118.36 128.52 105.54 - 102.69 -67.19 -79.98 148.50 160.78 122.02 -36.48 -101.92 -70.80 46.26 113.98 81.68 - 138.87 -30.75 -74.69 -98.94
0. I669 0.9166 0.2397 0.05 I7 -0.5728 -0.54 I2 0.7779 2.2683 1.0332 -0.8270 0.1582 - 1.0420 -0.8048 0.95 15 -0.3139 0.9885 - 1S296 -0.8520 0.4129
-0.4788 -1.2813 - 1.0878 0.3753 1.1587 2.6560 -0.5751 -0.8769 - 1.7800 0.5067 0.9100 3.3395 -0.8822 -2.3035 - 1.9492 0.8408 0.7944 2.9658 3.0264
0.0100 1.0377 2.42 I5 2.7099 1.5819 1.8318 -1.3218 1.0986 3.3561 3.8639 0.3827 0.6986 0.1011 0.6495 2.64 17 2.8263 1.4673 2.6620 1.9755
0.507 I 1.5754 1.1139 0.3788 1.2925 2.7106 0.9674 2.4319 2.0581 0.9699 0.9236 3.4983 1.1941 2.4923 1.9743 1.2977 1.7236 3.0858 3.0544
-70.78 -54.42 -77.57 82.16 116.31 101.52 -36.48 -21.14 -59.87 148.50 80.14 107.33 - 132.37 -67.56 -99.15 40.38 152.55 106.03 82.23
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
407
TABLE A4 Structure 7: (1+4)-P-~-Xylan
XY 1
Water
c-1 c-2 c-3 c-4 c-5 0-1 0-2 0-3 0-4 0-5
0.8932 1.9459 1.4675 0.1015 -0.8774 1.285 1 3.1731 2.3989 -0.3958 -0.3404
-0.45 16 -0.3192 - 1.0149 -0.5148 -0.5844 0.2849 -0.8510 -0.8272 - 1.2554 0.0866
0.0059 1.0885 2.3463 2.7680 1.5934 - 1.0890 0.6445 3.3724 3.8610 0.4693
1.0009 1.9719 1.7843 0.5247 1.0542 1.3163 3.2852 2.5375 1.3163 0.3512
-26.82 -9.32 -34.67 -78.84 - 146.33 12.50 -15.01 - 19.02 - 107.50 165.73
W
-2.6440
3.8238
- 1.2296
4.6489
124.66
TABLE A5 Structure 8:A-Amylose
Glc 1
c-I c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- I H-2 H-3 H-4 H-5 H-6 1 H-62
2.7932 3.9285 3.6291 3.1509 1.9926 1.5108 1.6915 4.3040 4.8459 2.7347 2.4106 2.5912 3.0287 4.6937 2.7984 3.861 1 1.222I 0.8147 1.1690
2.6739 1.6802 0.4179 0.8104 1.7806 2.2587 2.1814 1.4189 -0.3132 -0.3745 2.9597 2.7195 3.5517 2.0987 -0.0933 1.2547 1.2777 3.0122 1.4887
7.8475 7.8101 8.6065 9.9962 9.9267 1 1.2747 7.1 185 6.4685 8.6888 10.6900 9.1923 1 2.1043 7.4509 8.2527 8.1137 10.4762 9.4606 11.1817 11.7162
3.8667 4.2727 3.6531 3.2535 2.6723 2.7174 2.7604 4.5318 4.8560 2.7602 3.8 I72 3.7563 4.6677 5.1415 2.8000 4.0599 1.7681 3.1204 1.8928
43.75 23.16 6.57 14.42 41.78 56.22 52.21 18.25 -3.70 -7.80 50.84 46.38 49.54 24.09 -1.91 18.00 46.27 74.86 51.86 (‘continued)
408
RENGASWAMI CHANDRASEKARAN
TABLE A5 ( c o n h u e d )
Glc 2
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
Glc 3
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
Water
W
-0.7882 0.6359 1.5020 0.9015 -0.5083 - 1.2274 -0.8679 1.1141 2.7542 1.6915 -1.2912 - 1.3868 - 1.4169 0.6199 1.5232 0.8856 -0.4251 -2.2317 -0.7793
3.7772 4.2733 3.3217 3.1388 2.6100 2.4106 2.5853 4.49 13 3.9864 2.1814 3.5661 3.6400 4.4065 5.1335 2.3443 3.9850 1.6876 2.2147 1.6875
4.1841 4.2236 5.0243 6.4097 6.2633 7.5749 3.4336 2.9066 5.1098 7.1185 5.5032 8.2997 3.7629 4.6822 4.5539 6.8630 5.7833 7.4295 8.0175
3.8586 4.3203 3.6455 3.2657 2.6590 2.7051 2.7271 4.6274 4.8453 2.7604 3.7927 3.8952 4.6287 5.1708 2,7957 4.0822 1.7403 3.1441 1.8588
101.79 81.54 65.67 73.97 101.02 I 16.98 108.56 76.07 55.36 52.21 109.90 110.86 107.83 83.11 56.99 77.47 104.14 135.22 114.79
-3.70 17 -3.3475 -2.1 I 12 -2. I36 1 -2.4601 - 2.6 107 -2.7826 -3.3404 -2.0882 -0.8679 -3.7248 -3.5938 -4.5873 -4.0560 - 1.2753 -2.8516 - 1.6649 -2.9047 - 1.7534
1.1502 2.6153 3.0866 2.3882 0.9102 0.2996 0.3816 3.0325 4.4978 2.5853 0.7166 0.9839 0.9368 3.1051 2.6602 2.7537 0.4451 --0.6920 0.4099
0.7472 0.6553 1.4538 2.8051 2.7880 4.1595 0.0043 -0.699 I I .6238 3.4336 2.1059 4.9537 0.3955 1.1118 0.8873 3.3353 2.3090 4.1050 4.5860
3.8763 4.2480 3.7396 3.2041 2.623 1 2.6278 2.8086 4.5116 4.9589 2.727 1 3.793 1 3.7260 4.6820 5.1081 2.9501 3.9641 1.7234 2.9860 1.8007
162.74 142.00 124.37 131.81 159.70 173.45 172.19 137.77 114.90 108.56 169.11 164.69 168.46 142.56 115.61 136.00 165.03 - 166.60 166.84
2.9632
--6.1032
8.6290
6.7845
-64.10
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
409
TABLE A6 Structure 9: 9-Amylose
Glc 1
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- I H-2 H-3 H-4 H-5 H-61 H-62
Glc 2
c-1 c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
Water
w- 1 w-2 w-3 w-4 w-5 W-6
- 1.0637 0.2932 1.3616 0.8519 -0.4717 - 1.0822 - 1.0564 0.7104 2.5095 1.8028 - 1.4365 - 1.1 156 - 1.7843 0.2044 1SO87 0.7317 -0.3413 -2.0526 -0.4523
3.8099 4.4748 3.6241 3.1803 2.5282 2.0860 2.6916 4.7872 4.4556 2.2670 3.4142 3.1723 4.3947 5.2758 2.7285 3.9460 1.6390 1.7512 1.4147
4.3358 4.2359 5.0107 6.373 1 6.2629 7.5899 3.4736 3.0212 5.1563 6.9399 5.6555 8.5290 4.0279 4.8703 4.4 127 6.9295 5.6919 7.4807 7.9383
3.9556 4.4844 3.8714 3.2924 2.5718 2.3500 2.8915 4.8396 5.1137 2.8965 3.7041 3.3627 4.7431 5.2798 3.1 178 4.0133 1.6742 2.6981 1.4852
105.60 86.25 69.41 75.00 100.57 117.42 I 1 1.43 81.56 60.61 51.51 112.82 109.37 112.10 87.78 61.06 79.50 101.76 139.53 107.73
-3.8388 -3.7370 -2.4642 -2.3301 -2.4096 -2.3448 -2.8693 - 3.80 18 -2,6094 - 1.0564 -3.6797 -3.5076 -4.7073 -4.4669 - 1.6271 -3.0608 - 1.5901 -2.2838 - 1.5901
0.9805 2.4866 2.9896 2.3279 0.8219 0.1073 0.4262 3.0024 4.3979 2.6916 0.4614 0.3557 0.6457 2.8246 2.6483 2.6003 0.5335 -0.9244 0.4694
0.8788 0.7769 1.5465 2.9099 2.8018 4. I298 0.0156 -0.4389 1.6900 3.4736 2.1986 4.9369 0.5751 1.4175 0.9495 3.4663 2.2287 4.007 1 4.5895
3.9620 4.4887 3.8743 3.2937 2.5459 2.3473 2.9008 4.8444 5.1138 2.8915 3.7085 3.5256 4.7514 5.2850 3.1082 4.0162 1.6772 2.4638 1.6579
165.67 146.36 129.50 135.03 161.17 177.38 171.55 141.70 120.68 111.43 172.85 174.21 172.19 147.69 121.57 139.65 161.45 157.96 163.55
-6.9995 -6.3742 -5.9598 -7.4046 -6.6285 -5.0570
6.8043 8.2783 9.7394 3.7538 5.6139 3.9589
2.6125 4.9046 7.5098 7.3570 4.9286 7.6627
9.7617 10.4480 11.4182 8.3018 8.6864 6.4223
135.81 127.60 121.46 L53.12 139.74 141.94
TABLE A7 Structure 10: V-Amylose
Glc
c-1 c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
Water
w-1 w-2
3.2036 4.1504 4.1634 4.3709 3.4500 3.7353 1.8936 3.7613 5.1880 4.0597 3.5797 2.7107 3.2425 5.1232 3.2425 5.3696 2.45 14 4.6563 3.8391
4.0428 3.3465 1.8642 1.5273 2.3583 2.201 1 3.5936 3.6610 1.2578 0.1572 3.7508 2.7626 5.0759 3.7284 1.4374 1.7070 2.0888 2.6503 1.1679
2.68 15 1.7086 1.9459 3.4171 4.295 1 5.7664 2.3888 0.3718 1.1628 3.7098 4.0025 6.5732 2.5233 1.835I 1.6215 3.6781 4.0974 6.0037 5.9958
5.1582 5.3315 4.56 17 4.6300 4.1790 4.3356 4.0620 5.2488 5.3383 4.0627 5.1849 3.8704 6.0232 6.3362 3.5468 5.6344 3.2206 5.3577 4.0128
51.61 38.88 24.12 19.26 34.35 30.51 62.2 I 44.23 13.63 2.22 46.34 45.54 57.43 36.05 23.91 17.64 40.43 29.65 16.92
1.1543 5.5435
0.0000 3.2005
0.7752 1.1207
1.1543 6.401 1
0.00 30.00
TABLE A8 Structure 11: KOH-Amylose Group
Atom
x (A,
Glc 1
c-1
3.7380 3.7760 2.5940 2.5670 2.5710 2.6780 2.6230 3.7410 2.7710 1.4090 3.7270 3.8420 4.6080 4.6720 I .6950 3.4250 1.6990 1.8240 2.7260
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
Y (6) -0.3390 - 1.8600 -2.3970 - 1.6860 -0.1720 0.5250 0.0950 -2.3760 -3.8100 -2.0780 0.1990 0.1230 -0.0030 -2.1620 -2.2130 - 1,9680 0.1400 0.3170 1S600
z
(A)
6.27 10 6.3080 7.1370 8.4950 8.3560 9.6860 5.5120 4.9860 7.3010 9.2610 7.5850 10.4020 5.7900 6.7640 6.6260 9.0300 7.8610 10.2600 9.5 190
r (A)
4 (")
3.7533 4.2092 3.53 19 3.0712 2.5767 2.7290 2.6247 4.4318 4.71 11 2.5107 3.7323 3.8440 4.6080 5.1480 2.7875 3.9501 1.7048 1.8513 3.1408
-5.18 -26.22 -42.74 -33.30 -3.83 1 I .09 2.07 -32.42 -53.97 -55.86 3.06 1.83 -0.04 -24.83 -52.55 -29.88 4.7 1 9.86 29.78
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
41 1
TABLE A8 (co,7tinued)
Glc 2
c-1
2.1340 3.4850 3.4080 2.8160 1.4980 0.9860 1.1920 3.8800 4.7340 2.6230 1.7050 1.8100 2.2480 4.1980 2.7960 3.5010 0.7790 0.9440 0.0160
2.9130 2.2100 0.9340 1.2810 2.03 10 2.5000 2.1320 1.9020 0.4060 0.0950 3.2010 3.5250 3.8250 2.8570 0.2270 1.8990 1.4150 1.6880 2.8810
2.4770 2.4860 3.3440 4.7140 4.6100 5.9460 1.7620 1.1570 3.4770 5.5120 3.8000 6.5000 1.9670 2.9090 2.8660 5.2150 4.1570 6.6100 5.8190
3.61 10 4.1267 3.5337 3.0937 2.5237 2.6874 2.4426 4.321 1 4.7514 2.6247 3.6268 3.9625 4.4367 5.0780 2.8052 3.9829 1.6153 1.9340 2.8810
53.77 32.38 15.33 24.46 53.59 68.48 60.79 26.11 4.90 2.07 61.96 62.82 59.56 34.24 4.64 28.48 61.17 60.78 89.68
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- I H-2 H-3 H-4 H-5 H-6 I H-62
- 1.5560 -0.2500 0.8300 0.2500 - 1.0420 - 1.6480 - 1.2504 0. I980 1.9480 1.1920 - 1.9650 -0.8460 -2.2980 -0.4200 I .6950 0.0490 -0.8780 -2.6080 - 1.7310
3.2470 4.0240 3.2970 2.9 130 2.1210 1.8470 2.0983 4.2530 4.1800 2.1320 2.9540 0.9520 3.8440 4.9580 -2.2130 3.7960 1.2220 2.7550
-1.1580 -1.1890 -0.3670 1.0010 0.8910 2.2420 - 1.9780 -2.5180 -0.2190 1.7620 0.1700 3.0110 - 1.6010 -0.7420 6.6260 1.5320 0.3730 2.1190 2.7630
3.6006 4.0318 3.3999 2.9237 2.3631 2.4753 2.4426 4.2576 4.6116 2.4426 3.5479 1.2736 4.4785 4.9785 2.7875 3.7963 1.5047 2.9796 3.2537
115.60 93.56 75.87 85.09 116.16 131.74 120.79 87.33 65.01 60.79 123.63 131.63 120.87 94.84 -52.55 89.26 125.70 151.08 122.14
Ion
K
-2.6880
0.7560
8.9740
2.7923
164.29
Water
w-I
-0.6170 0.3980 -2.1350 2.6330
-0.6550 -0.4040 -0.2330 3.2780
6.95 10 -0.1270 4.9170 - 2.8210
0.8998 0.5671 2.1477 4.2045
- 133.29 -45.43 - 173.77 51.23
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H-1 H-2 H-3 H-4 H-5 H-6 I H-62 Glc 3
c-1
w-2 w-3 w-4
1.4410
TABLE A9 Structure 12: 2,3,6-Tri-O-ethylamylose
Et3-Glc
c-1 c-2 c-3 c-4
c-5 C-6 (2-21 c-22 C-3 1 C-32 C-6 1 C-62 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-2 1 H-22 H-23 H-24 H-25 H-3 H-31 H-32 H-33 H-34 H-35 H-4 H-5 H-61 H-62 H-63 H-64 H-65 H-66 H-67
0.8400 1.1890 2.0740 3.2720 2.8480 4.0010 -0.41 10 - 1.7950 1.6440 2.2950 5.3670 5.1890 0.0000 -0.0200 2.5620 3.8700 2.0120 4.4060 0.2750 1.6940 -0.3250 0.2980 -2.4100 - 1.7310 -2.2030 1.5130 0.8100 1.3100 2.0240 1.9790 3.3380 3.9410 2.3170 3.7420 4.8210 5.3280 6.3320 6.1300 4.5980 4.7190
1.2124 0.0198 -0.9635 -0.2490 0.9923 1.8396 -0.181 0 0.4233 - 3.0093 -4.0644 2.4081 2.6360 0.7970 -0.5914 -1.9618 - 1. I560 1.8305 1 S275 1.9056 0.3558 -0.9894 0.4918 -0.2163 1.3567 0.5491 - 1.4262 -2.6163 -3.4406 -5.0169 -3.9544 -3.9584 0.0325 0.6953 2.855 1 1.7346 3.3299 2.0376 2.6349 I .8675 3.5602
2.221 1 3.1073 2.3494 1.7328 0.9389 0.4372 4.845 1 4.9614 3.5376 4.3920 - 1.4566 -2.9599 1.1560 3.5465 3.2484 0.7970 1.7539 -0.9023 2.7726 3.9648 5.5095 5.2288 5.5235 5.4379 4.0030 1.5914 4.0410 2.6402 4.0421 5.3872 4.3472 2.49 17 0.0827 0.4972 1.0846 -0.9557 - I .2693 -3.4269 -3.3634 -3.1219
2.5305 3.1074 2.5393 1.7506 1.3661 1.8908 4.8485 4.9794 4.6444 5.984 1 2.8143 3.9635 1.4041 3.5955 3.7948 1.4041 2.5351 1.7741 3.3643 3.9807 5.5976 5.2519 5.5277 5.6046 4.0405 2. I370 4.8140 4.3369 6.4427 6.6828 5.8794 2.4919 0.7002 2.8981 2.0458 3.4643 2.4006 4.3228 3.8471 4.735 I
28.63 0.37 -22.30 -8.18 46.58 76.63 -2.14 4.88 -40.39 -42.78 121.17 138.31 34.59 -9.47 -31.13 -55.41 46.22 120.57 34.50 5.13 -10.18 5.37 -2.24 14.01 7.81 -41.87 -32.92 -52.50 -51.14 -36.28 -42.32 0.75 83.22 80.12 57.98 106.01 121.92 142.44 150.96 131.25
TABLEAIO Structure 13: Sodium Pectate
~
GalA 1
c-1 c-2 c-3 c-4
-0.4682 0.6956 1.3684 0.3440
~
0.9247 1.3471 0.1 270 -0.7420
~
~~~
9.4796 10.3654 10.9759 I 1.6907
1.0365 1.5161 1.3743 0.8179
116.85 62.69 5.30 -65.13
POLYSACCHARIDE HELICES UV ORIENTED FIBERS
413
TABLE A10 (conrinued)
- 1.0631
10.7582
- 1.8009
1 I .4542
0.1898 2.1020 0.5480 -0.067 1 0.1555 -1.1730 -2.9453 -0.0442
8.3854 9.5945 1 1.9004 12.8383 10.2411 11.5317 11.8630
1.3414 2.6469 0.1953 2.6554 2.435 1 0.1792 1.3856 3.2370 3.3737
- 127.58 -137.13 76.33 52.33 13.00 -158.01 173.55 - 158.75 -119.19
- 1.2372 0.0856 1.2529 2.5942 -0.1227 -2.4444 -2.3174 0.1898 1.1287 3.0537 3.0709
5.0254 5.91 12 6.5217 7.2378 6.3039 7.0013 3.9312 5.1416 7.4476 8.3854 5.7882 7.3888 7.1002
1.0572 1.5167 1.3548 0.7983 1.3450 2.6557 0.2045 2.6527 2.4181 0. I953 1.4094 3.0990 3.5189
-2.40 -56.38 - 114.05 173.84 1 1 1.33 102.35 -36.87 -67.15 - 106.59 76.33 53.21 80.20 119.23
0-61 0-62
-0.5445 -1.4917 -0.7727 0.4925 1.3499 2.5506 -0.1662 -2.6093 - 1.6385 0.1636 0.5764 2.4121 3.5280
-0.8804 -0.0828 1.1102 0.6579 -0.1898 -0.7920 -0.067 I 0.3425 1.7695 -0.1227 - 1.2829 -1.9821 -0.0228
0.5725 1.4583 2.0688 2.7849 1.8510 2.5471 -0.5217 0.6874 2.9933 3.9312 I .3340 2.9065 2.6754
1.0352 1.4940 1.3526 0.8218 1.3632 2.6707 0.1792 2.6317 2.41 I6 0.2045 1.4064 3.1220 3.528 1
Ions
Na- 1 Na-2 Na-3
2.4373 2.1789 4.371 1
3.4890 3.3335 0.7463
-0.8297 5.6459 10.4996
4.2560 3.9824 4.4344
55.06 56.83 9.69
Water
w-I
3.2561 4.6430 - 5.1754 -3.3235 -3.5770 -0.2 165 1.1822
2.7684 1.9464 3.002 I -3.1337 2.3341 3.3678 4.4665
1.7729 5.3146 7.0516 5.6902 3.9147 -0.1750 3.3974
4.2739 5.0345 5.983 I 4.5679 4.27 I2 3.3747 4.6203
40.37 22.74 149.88 - 136.68 146.87 93.68 75.18
GalA 2
c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62
-0.8180 - 1.9398 0.0461 1.6226 2.3726 -0.1662 - 1.3768 -3.0170 - 1.6453
c-1
1.0563 0.8399 -0.5521 -0.7937 -0.489 I -0.5680 0. I636 1.0303 -0.6905 0.046 I 0.8440 0.5277 - 1.7183
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5
0-6I 0-62 GalA 3
c-1 C-2 c-3 C-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5
w-2 w-3 w-4 w-5 W-6 w-7
- 1.2629
-121.73 - 176.82
124.84 53.18 -8.00 - 17.25 - 158.01 172.52 132.80 -36.87 -65.81 -39.41 -0.37
RENGASWAMI CHANDRASEKARAN
414
TABLE A1 1 Structure 14: Pectic Acid
GalA
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 1 0-62
-1.4167 - 1.6395 -0.3118 0.4228 0.5425 1.1316 -0.6445 -2.2760 -0.5534 -0.288 1 -0.7643 0.2891 2.3849
-0.3124 0.8426 1.2927 0.1 156 -1.0184 -2.2718 0.1538 1.9102 2.2878 -0.3580 -1.3641 -3.0898 -2.3284
-0.0159 0.9475 1.5486 2.1736 1.1664 1.7715 -1.1080 0.2588 2.5425 3.3162 0.6648 2.2015 1.7636
1.4507 1.8433 I .3298 0.4383 1.1539 2.5380 0.6626 2.9714 2.3538 0.4595 1 S636 3.1033 3.3330
- 167.56 152.80 103.56 15.30 -61.96 -63.52 166.58 139.99 103.60 - 128.83 - 1 19.26 -84.65 -44.3 1
TABLE A I2 Structure 15: Poly @-o-ManA)
ManA
C- 1
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62
-0.0086 -0.6020 0.0602 -0.0258 0.4902 0.3354 -0.7052 - 1.9866 -0.5418 0.7052 -0.1806 -0.7826 1.1524
0.3876 1.3604 1.1552 -0.2888 -1.2160 -2.7132 0.5016 1.0944 1.9988 -0.5016 -0.9500 -3.2376 -3.3744
2.3920 3.4008 4.7528 5.2000 4.0872 4.4096 1.1960 3.5256 5.7096 6.3960 2.8704 3.9416 5.0232
0.3877 1.4876 1.1568 0.2900 1.3111 2.7339 0.8654 2.2681 2.0709 0.8654 0.9670 3.3308 3.5658
91.27 113.87 87.02 -95.10 -68.04 -82.95 144.58 151.15 105.17 -35.42 - 100.76 - 103.59 -71.14
z 6,
r (A)
4 (7
1 .8966 2.8188 3.2364 3.8 193 2.8710 3.4365
1.1196 1.5305 1.3977 1.0063 1.3446 2.7350
127.71 178.71 -121.89 -53.45 5.87 14.01
TABLEA13 Structure 16: Poly ((Y-L-GuIA)
Group
Atom
CulA
c-1 c-2 c-3 c-4 c-5 C-6
x (A,
-0.6848 - 1.5301 -0.7383 0.5992 1.3375 2.6536
Y
(A,
0.8858 0.0344 -1.1868 -0.8084 0.1376 0.6622
415
POLYSACCHARIDE HELICES IN ORIENTED FIBERS TABLE A 13 (continued)
Group
Water
rid)
Atom 0-1 0-2 0-3 0-4 0-5 0-6 1 0-62
-0.3959 -2.7285 -0.5350 0.3959 0.5234 3.7129 2.7392
0. I548 -0.3268 -2.0124 -0.1548 1.2384 0.0258 1.5910
0.7134 2.201 1 2.1054 5.0634 2.5404 2.9928 4.2282
0.425 1 2.7480 2.0823 0.425 1 1.3448 3.7130 3.1677
w
-5.2965
-0.3 182
1.0614
5.3060
4 (7 158.64 - 173.17
- 104.89 -21.36 67.05 0.40 30.15 - 176.56
TABLEAI~ Structure 17: Curdlan I
Group
Atom
x (6,
Glc
c-I c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6
-2.5190 -2.1920 - 3.0630 -4.5810 -4.7590 - 6.1740 - 1.7980 -0.8130 -2.8389 -5.3910 -3.9030 -7.1290 -2.2780 -2.3620 -2.7910 -4.9160 -4.5090 -6.2680 -6.4070
H- 1 H-2 H-3 H-4 H-5 H-61 H-62
Y
(A,
1.1230 0.8420 -0.2830 0.0410 0.3500 0.7600 2.2400 0.5 150 -0.437 I - 1.0840 1.4370 -0.2060 0.2250 1.7520 - 1.2270 0.9030 -0.5420 0.8690 1.7190
z
(A,
-0.0100 1.4510 1.9860 1.6890 0.2060 -0. I400 -0.4140 1.5690 3.3860 2.0190 -0.1790 0.2980 -0.5990 2.0460 1.4890 2.2860 -0.3870 - 1.2300 0.3460
r
iW)
+
(")
2.7580 2.3482 3.0760 4.5812 4.77 19 6.2206 2.8724 0.9624 2.8724 5.4989 4.1591 7.1320 2.2891 2.9408 3.0488 4.9982 4.5415 6.3280 6.6336
155.97 158.99 - 174.72 179.49 175.79 172.98 128.75 147.65 - 171.25 - 168.63 159.79 - 178.34 174.36 143.43 - 156.27 169.59 - 173.15 172.11 164.98
3.5457 2.9983 3.7861 5.2472 5.4476
144.79 153.42 175.33 171.26 163.50 (continued)
TABLE A 15
Structure 19: Curdlan I11
Glc
c-1 c-2 c-3 c-4 c-5
-2.8970 -2.6815 -3.7735 -5.1863 -5.2233
2.0444 1.3415 0.3080 0.7969 1.5469
0.0280 1.3620 1.5950 1.2900 -0.0330
416
RENGASWAMI CHANDRASEKARAN
TABLE A I5 (continued) ~~
~
C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
-6.5315 -2.0160 -1.3977 -3.7187 -6.0883 -4.2252 -7.5307 -2.7129 -2.7207 -3.5794 -5.4909 -5.0365 -6.3179 -6.8763
2.257 1 3.1300 0.71 11 -0.1809 -0.3012 2.5757 1.3803 I .393 1 2.0558 -0.5038 1.4474 0.8767 3.0530 2.6479
-0.2790 0.0000 1.3740 2.9400 1.2370 -0.0360 -0.8040 -0.7750 2.1310 0.9580 2.0560 -0.8190 -0.9460 0.6330
6.9105 3.7231 1.5682 3.7231 6.0957 4.9484 7.6562 3.0497 3.4100 3.6147 5.6785 5.1122 7.0710 7.3685
160.94 122.79 153.03 -177.21 -177.17 148.63 169.61 152.82 142.93 -171.99 165.23 170.13 154.42 158.94
TABLE A16 Structure 21: (143)-a-D-Gtucan
Glc 1
Glc 2
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
-0.3218 0.2494 -0.4702 - 1.9687 -2.4693 -3.9182 -0.0306 1.6433 0.0148 -2.645 1 - 1.7092 -4.1828 0.1414 0.1182 -0.2821 -2.1882 -2.3567 -4.5391 -4. I457
1.1306 1.1097 0.0594 0.2990 0.4018 0.8375 -0.1054 0.8 I03 0.0426 -0.7903 1.3915 2.0340 1.9020 2.0520 -0.8797 1.1896 -0.5282 0.0658 1.0156
4.8680 6.2750 7.0980 7.0770 5.6440 5.5520 4.2390 6.2020 8.4400 7.7030 4.9320 6.2920 4.3270 6.7190 6.6680 7.5890 5.1700 5.8990 4.5420
1.1755 1.1374 0.4739 1.9913 2.5018 4.0067 0.1098 1.8322 0.045 1 2.7606 2.2040 4.65 11 1.9072 2.0554 0.9238 2.4906 2.4152 4.5396 4.2683
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2
0.2994 -0.2881 0.4348 1.9301 2.4072 3.8591 0.0148 - 1.6777
- 1.1885 -1.1368 -0.0890 -0.3413 -0.4200 -0.8385 0.0426 -0.8327
0.6450 2.0450 2.8910 2.8400 1.3970 1.2740 0.0000 1.9520
1.2256 1.1727 0.4438 1.9600 2.4436 3.9492 0.045 I 1.8730
105.89 77.33 172.80 171.36 170.76 167.93 - 106.20 26.25 70.81 -163.36 140.85 154.07 85.75 86.70 - 107.78 151.47 -167.37 179.17 166.24 -75.86 - 104.22
-11.56 - 10.03 -9.90 - 12.26 70.8 1 -153.60
TABLE A16 (continued)
Group
Atom 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
x
(6,
-0.0306 2.6259 1.6826 4.1012 -0.1676 -0.1739 0.2422 2.1485 2.2610 4.4674 4.1 196
Y
(A,
-0.1054 0.7246 - 1.4464 -2. I493 - 1.9637 -2.0782 0.8597 - 1.2444 0.5047 -0.145 I -0.8340
z
(6,
4.2390 3.4830 0.7000 1.7950 0.1 120 2.4970 2.4830 3.3280 0.9220 1.7740 0.2560
0.1098 2.7240 2.2188 4.6303 1.9708 2.0855 0.8932 2.4829 2.3 166 4.4698 4.2032
- 106.20 15.43 -40.68 -27.66 -94.88 -94.78 74.27 -30.08 12.58 -1.86 -11.44
TABLEAI~ Structure 22: Galactoglucan
Glc6Ac A
Ga14,6-Pyr B
c-1 c-2 c-3 c-4 c-5 C-6 c-7 C-8 0-1 0-2 0-3 0-4 0-5 0-6 0-7 H- 1 H-2 H-3 H-4 H-5 H-61 H-62 H-8 1 H-82 H-83
0.6193 0.2776 1.5303 2.2210 2.5088 3.1550 3.7512 3.8433 -0.5654 -0.3488 1.1800 3.4430 1.2848 3.9283 3.5449 I .280 1 -0.4466 2.2104 1.5652 3.1871 2.3749 3.8200 3.6081 3.1263 4.8627
-0.6721 -0.4856 - 1.8273 -2.4254 - 3.792 1 -5.0470 -4.7420 - 1.6472 0.5792 0.0945 -1.6531 -2.5839 -3.9422 -6.1397 -0.6925 - 1.2902 0.1903 -2.4923 - 1.7605 -4.5676 -3.9358 -3.681 1 -5.3696 -4.9532
4.9997 6.3216 7.1639 7.3694 5.9964 6.0783 7.9777 9.4547 4.3396 6.0628 8.4219 8.0834 5.2624 7.2682 7.4756 4.4 122 6.8725 6.6249 7.9506 5.4415 6.0735 5.2140 9.6256 10.0043 9.8100
1.4824 0.7272 1.6055 2.8761 3.4895 4.9329 6.2884 6.1039 1.7415 0.676 1 1.1838 3.8193 2.8857 5.5653 7.0896 1.4554 1.3653 2.2186 2.9430 3.6410 5.1481 5.4848 5.1545 6.2 134 6.94 12
C -1 c-2 c-3 c-4 c-5 C-6
-2.0436 -1.9713 -0.5673 -0.0858 -0.2692 0.0464
-1.0801 -1.1005 - 1.4555 -2.7309 -2.6445 -3.9397
0.9375 2.4586 2.9235 2.2446 0.7331 0.0155
2.3115 2.2577 1.5621 2.7322 2.6582 3.9400
- 1.3468
-65.31 -67.56 -17.61 -39.45 -44.03 -50.24 -53.38 -50.98 - 108.94 121.05 4.58 -25.65 -63.56 -45.10 -60.00 -28.41 - 109.09 4.92 -57.87 -28.92 -62.53 -45.86 -45.57 -59.79 -45.53 -152.14 - 150.83
-111.29 -91.80 -95.81 -89.33 (continued)
TABLE A17 (continued)
c-7 C-8 c-9 0-I 0-2 0-3 0-4 0-5 0-6 0-81 0-82 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 H-9 1 H-92 H-93
Ion Water
K
w- 1 w-2 w-3
-0.3666 1.1078 - 1.1526 1.1800 -2.3638 -0.5654 -0.8225 - 1.6373 -0.5330 1.7414 1.5680 -3.0778 -2.6846 0.1023 0.9796 0.4000 1.1371 -0.3435 -0.4757 - 1.8788 - 1.6887
-5.0824 -5.2820 -6.2084 0.0945 0.1699 - 1.6472 -3.8556 -2.3463 -5.0346 -6.1328 -4.5792 -0.8698 -1.8410 -0.6218 -2.8867 - 1.8723 -4.0612 -3.8942 -6.9202 -5.8249 -6.7 162
2.1435 2.5000 2.6956 8.4219 2.9653 4.3396 2.7 198 0.4144 0.7240 1.8387 3.4256 0.6272 2.8498 2.6653 2.4699 0.3259 -0.0595 -1.0121 3.1908 3.4274 1.8803
5.0956 5.3969 6.3145 1.1838 2.3699 1.7415 3.9423 2.861 I 5.0627 6.3752 4.8402 3.1984 3.2552 0.6302 3.0484 1.9145 4.2174 3.9093 6.9365 6.1204 6.9252
-94.13 -78.15 - 100.52 4.58 175.89 - 108.94 - 102.04 - 124.9 1 -96.04 -74.15 -71.10 - 164.22 - 145.56 -80.66 -71.26 -77.94 -74.36 -95.04 -93.93 - 107.88 -104.11
3.0799
-3.5921
1.0925
4.7317
-49.39
3.0838 -0.4347 -2.8120
-6.8288 -4.5064 2.393 1
4.677 1 5.6035 5.7958
7.4928 4.5273 3.6924
-65.70 -95.51 139.60
TABLE A 18 Structure 23: darrageenan
Gal4S0,- A
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 S
0-s1 0-s2 043
0.5493 0.7420 -0.6040 - 1.4494 - 1S291 -2.2628 1.7955 1.491 1 -0.4019 -0.8763 -0.2105 -2.2402 - 1.8347 - 1.3389 - 1.8585 -3.1772
I .5981 1.9318 2.1158 3.131 1 2.1542 3.7874 1S735 0.8952 2.5620 4.4327 2.6355 3.4462 5.5764 6.8760 5.4996 5.3891
6.7332 8.2099 8.8952 8.1382 6.6641 5.8354 6.1223 8.8314 10.2366 8.2444 6.1090 4.4490 8.8234 8.4171 10.2710 8.3082
1.6899 2.0694 2.2003 3.4503 3.1502 4.41 19 2.3874 1.7392 2.5933 4.5185 2.6439 4.1103 5.8705 7.0051 5.805 1 6.2559
7 1.03 68.99 105.93 114.84 119.04 120.86 4 1.23 30.98 98.92 101.18 94.57 123.03 108.21 101.02 108.67 120.52
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
419
TABLE A 18 (continued) 3,6An-Ga12S03-B
C-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 S
0-s1 0-s2 0-S3
2.7658 3.4197 3.3734 1.9143 1.6802 2.9524 2.4 197 2.1217 3.9833 1.7955 1.5517 3.3781 2.4090 4.5362 3.9048
2.2605 3.4875 4.6588 4.95 10 3.7345 3.7027 I .3866 3.8966 4.2418 6.1223 2.5872 3.4557 3.6150 4.2843 2.0666
0.0673 -0.5835 0.4057 0.7716 1.6634 2.4927 -0.9329 - 1.7650 1.6297 1.5735 0.7874 -3.1559 -4.2220 -3.4277 -3.1483
2.7666 3.469 1 3.3977 2.0640 2.3643 3.8640 2.5933 3.2439 4.3038 2.3874 1.7401 4.6229 4.8609 5.6856 5.0159
1.39 -9.68 6.86 2 I .95 44.71 40.17 -21.08 -32.96 22.25 41.23 26.91 -43.05 -60.29 -37.08 -38.88
TABLE A19 Structure 24: K-Carrageenan
Gal4SO; A
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 S
0-sI 042 0-S3 3,6 An-Gal B
c-I c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5
-0.2249 -0.1853 - 1.5390 -2.6366 -2.5559 -3.5499 0.9853 0.8305 - I S207 -2,4975 - 1.2494 -3.4925 -3.7514 -3.7471 -3.6657 -4.9782
2.1754 2.4836 2.2104 2.9508 2.6371 3.4326 2.5638 1.6998 2.6340 4.3590 2.9570 3.0880 5.1116 6.5019 5.0357 4.4797
4.8405 6.33 I 5 6.9688 6.2 I60 4.7258 3.9066 4.2803 6.9469 8.3333 6.3926 4.2228 2.5230 7.0417 6.6298 8.4872 6.5966
2.1870 2.4905 2.6934 3.9571 3.6724 4.9381 2.7466 1.8918 3.0415 5.0238 3.2101 4.661 9 6.3405 7.5044 6.2286 6.6970
95.90 94.27 124.85 131.78 134.10 135.96 68.98 63.96 120.00 119.81 112.91 138.52 126.27 119.96 126.05 138.02
3.0043 3.4955 3.0224 1.4895 1.3534 2.4270 3.0415 2.9609 3.4663 0.9853 1.6363
1.0914 0.6472 1.6648 1.7477 2.5094 3.5728 0.0000 -0.6286 2.963 1 2.5638 1.5688
0.8338 2.2 164 3.2623 3.2306 1.9153 2.0603 0.0000 2.5868 2.8649 4.2803 0.8500
3.1964 3.5549 3.4506 2.2963 2.851 1 4.3192 3.0415 3.0269 4.5602 2.7466 2.2669
19.97 10.49 28.85 49.56 61.66 55.81 0.00 -11.99 40.52 68.98 43.79
420
RENGASWAMI CHANDRASEKARAN
TABLE A20 Structure 25: Agarose Group
Atom
x
(A)
Y
(A)
Gal A
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6
2.8465 1.4568 1.3162 2.4474 3.7947 4.9560 2.9697 0.4834 0.0207 2.3108 3.8299 5.1504
-2.6175 -3.1240 -3.2905 -4.1549 -3.6136 -4.4938 -2.6090 -2.2169 -3.9619 -5.4971 -3.5218 -4.4614
3.6550 4.01 10 5.5170 6.0590 5.5960 6.0080 2.2710 3.51 10 5.8240 5.5950 4. I630 7.4140
3.8670 3.4470 3.5440 4.8221 5.2400 6.6900 3.9530 2.2690 3.9620 5.9630 5.2030 6.8140
-42.60 -65.00 -68.20 -59.50 -43.60 -42.20 -41.30 -77.70 - 89.70 -67.20 -42.60 -40.90
3,6 An-L-Gal B
c-1
3.2185 4.5189 4. I628 3.1897 1.9619 2.0931 3.4208 5.1 192 3.5166 2.9697 2.1067
0.6373 -0.0236 - 1.4252 - I .3408 -0.9910 - 1.9519 1.9989 0.7013 -2.1466 -2.6090 0.3981
-0.4720 0.0010 0.5090 1.6600 0.8250 -0.34 I 0 -0.5060 1.0820 -0.5240 2.2710 0.4260
3.2810 4.5 190 4.4000 3.4600 2.1980 2.8620 3.9620 5.1670 4.1200 3.9530 2.1440
11.20 -0.30 - 18.90 -22.80 -26.80 -43.00 30.30 7.80 -31.40 -41.30 10.70
c-2
c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5
TABLE A2 1 Structure 26: Sodium Hyaluronate I Group
Atom
x (A)
GlcNAc A
c-1
0.3867 -0.9900 -0.9198 0.1484 1.4716 2.5467 -3.2865 -4.126 1 0.2987 -1.9315 -2.1896 0.3422 1.2976 3.7918 -3.7602
c-2 c-3 c-4 c-5 C-6 c-7 c-8 0-1 N-2 0-3 0-4 0-5 0-6 0-7
(A)
z (A)
r (A)
-3.1124 -3.2459 -2.9521 -3.8136 -3.671 I -4.5919 -2.5714 -1.5517 -3.5159 -2.323 I -3.2152 - 3.4 160 -3.9965 -4.4001 -3.5159
6.5708 7.2055 8.6988 9.3573 8.6140 9.1502 6.6217 5.8886 5.2437 6.5334 9.2996 10.7115 7.2258 8.48 16 7.2326
3.1363 3.3935 3.092 1 3.8165 3.9551 5.2508 4.1729 4.4082 3.5286 3.0212 3.8900 3.4331 4.2019 5.8085 5.1479
Y
-82.92 - 106.96
- 107.30 -87.77 -68.16 -60.99 -141.96 - 159.39 -85.14 - 129.74 - 124.26 -84.28 -72.01 -49.25 - 136.92
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
42 1
TABLE A2 1 (continued)
GlcA B
Ion
H-1 H-2 H-3 H-4 H-5 H-6 1 H-62 H-N H-81 H-82 H-83
0.7418 - 1.3688 -0.6814 -0.169 I 1.8346 2.6970 2.2381 - 1.6002 -3.5881 -4.3239 -5.0805
-2.0760 -4.2656 - 1.8890 -4.8669 -2.6357 -4.395 I -5.6383 - 1.5765 -0.5944 -1.9058 - 1.4133
6.6760 7.0527 8.8516 9.3437 8.7056 10.2227 9.01 11 6.05 15 5.8479 4.8670 6.4214
2.2045 4.4798 2.008 1 4.8698 3.21 13 5.1566 6.0663 2.2463 3.6370 4.7253 5.2734
-91.99 -55.16 -58.47 -68.35 -135.43 - 170.59 -156.21 - 164.45
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62 H- 1 H-2 H-3 H-4 H-5
2.2391 2.8553 1.8692 1.3539 0.8209 0.3986 3.2152 3.2469 2.5101 0.2987 1.8376 -0.8021 1.3055 1.3609 3.765 I 1.0226 2.1709 -0.0534
-2.685 I -3.7958 -4.2764 -3.0975 -2.0086 -0.7615 -2.1896 -4.8668 -5.2170 -3.5159 - 1.6121 -0.7348 0.08 11 -3.0738 -3.42 19 -4.7798 -2.6921 -2.3884
1.6698 2.5116 3.5637 4.3817 3.455 1 4.2052 0.8146 1.6597 4.4258 5.2437 2.5217 4.55 14 4.3817 1.1336 3.0037 3.0716 4.9960 2.9087
3.4962 4.7498 4.667 1 3.3805 2.1699 0.8595 3.8900 5.8505 5.7894 3.5286 2.4445 1.0878 1.3080 3.3616 5.0878 4.8880 3.4583 2.3890
-50.18 -53.05 -66.39 -66.39 -67.77 -62.37 - 34.26 -56.29 -64.31 -85.14 -41.26 - 137.51 3.55 -66.12 -42.27 -77.92 -51.12 -91.28
Na
-0.4461
0.9544
2.4810
1.0535
115.05
z (A)
r (A)
4 (")
4.9390 5.9394 7.3559 7.4385 6.3555 6.3099 5.9650
1.5668 1.5588 1.6306 2.9904 3.4102 4.9234 2.7001
-63.36 - 106.41 -86.46 -68.65 -50.84 - 50.96 - 170.69
-70.34 - 107.79 - 109.84
TABLE A22 Structure 30: Sodium Hyaluronate I11
Group GlcNAc A
Atom
c-1 c-2 c-3 c-4 c-5 C-6 c-7
x
(A,
0.7025 -0.4404 0.1007 1.0886 2.1535 3.1009 -2.6645
y
(A,
- 1.4005
- 1.4953 - 1.6275 -2.7852 -2.6442 -3.8242 -0.4370
(continued)
422
RENGASWAMI CHANDRASEKARAN TABLE A22 (continued)
C-8 0-I N-2 0-3 0-4 0-5 0-6 0-7 H- 1 H-2 H-3 H-4 H-5 H-61 H-62 H-N H-8 1 H-82 H-83
-3.4153 0.1655 - 1.2997 -0.9795 1.7320 1.5375 2.42 I0 -3.21 16 1.2952 - 1.0656 0.6042 0.5526 2.7503 3.8720 3.5802 -0.9105 -3.1083 -3.1904 -4.4964
0.8645 -1.4146 -0.2972 - 1.8533 -2.8010 -2.5553 -5.0579 - 1SO30 -0.4967 -2.3687 -0.6944 -3.7359 - 1.7392 -3.7054 -3.8739 0.55 10 1.5602 1.3069 0.6757
5.8140 3.6565 5.8168 8.2621 8.7096 5.0616 6.5408 6.1959 5.1414 5.7029 7.6437 7.3017 6.5436 7.0851 5.3210 5.6373 6.6063 4.8307 5.8909
3.5230 1.4242 1.3332 2.0962 3.2932 2.9822 5.6075 3.5459 1.3872 2.5973 0.9205 3.7765 3.2541 5.3593 5.2749 1.0643 3.4779 3.4477 4.5469
165.80 -83.33 -167.12 - 117.86 -58.27 -58.97 -64.42 - 154.92 -20.98 - 1 14.22 -48.97 -81.59 -32.31 -43.74 -47.26 148.82 153.35 157.72 171.45
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62 H- 1 H-2 H-3 H-4 H-5
1.3672 2.3025 1.5922 0.9822 0.1199 -0.4232 2.0947 2.7675 2.5223 0.1655 0.8941 - 1.6492 0.4249 0.5141 3.1850 0.7978 1.7857 -0.7343
-0.52 18 - 1.4315 -2.0007 -0.8787 0.0181 1.2208 0.0760 -2.4746 -2.7378 -1.4146 0.5224 1.4174 1.8614 -1.1068 -0.8588 -2.6886 -0.2826 -0.5569
-0.2 166 0.5700 1.7898 2.6191 1.7356 2.4795 - 1.2369 -0.2765 2.5849 3.6565 0.6384 2.3398 3.1379 -0.5871 0.8949 1.4620 3.0752 1.3509
1.4634 2.71 12 2.5569 1.3179 0.1213 1.2921 2.0961 3.7125 3.7226 1.4242 1.0355 2.1746 1.9093 1.2204 3.2987 2.8045 1.8079 0.9216
-20.89 -31.87 -51.49 -41.82 8.59 109.12 2.08 -41.80 -47.35 -83.33 30.30 139.32 77.14 -65.09 -15.09 -73.47 -8.99 - 142.82
Ion
Na
- 3.4710
-0.1363
1.5960
3.4737
- 177.75
Water
w-1
0.01 86 - 3.2016 3.2255 -5.3800
2.1358 2.05 16 - 5 .O 158 0.4674
6.7545 0.0000 -1.1400 3.3060
2.1359 3.8025 5.9634 5.4003
89.50 147.35 -57.26 175.03
GlcA B
w-2 w-3 w-4
TABLE A23 Structure 32: Potassium Hyaluronate Ill
GlcNAc A
c-I
1.3150 2.4770 2.3750 2.2020 1.0510 0.9250 3.6630 3.4940 1.5440 2.4710 3.5700 1.9220 1.2630 I .5510 4.7470 0.3770 3.4290 1.5280 3.1290 0.1040 -0.1390 1.4030 1.6540 2.8240 3.0600 4.4740
3.2940 2.5000 2.4620 3.8630 4.5930 6.0340 0.4430 -0.9810 3.4410 1.1300 1.8980 3.8000 4.6050 6.9290 0.9340 2.7620 2.9660 1.8290 4.4370 4.0830 6.3040 6.1570 0.7390 -1.5190 -0.9810 - I .4800
6.4380 7.0210 8.5380 9. I080 8.4240 8.8700 6.3650 5.8900 5.0760 6.4590 9.0840 10.5050 7.0040 7.9530 6.6370 6.6560 6.7280 8.8390 8.9610 8.6560 8.9440 9.8530 6.1710 6.5770 4.8790 5.8690
3.5468 3.5 I93 3.4208 4.4465 4.71 17 6.1045 3.6897 3.6291 3.7715 2.7171 4.0432 4.2584 4.775 1 7.1005 4.8380 2.7876 4.5338 2.3833 5.4293 4.0843 6.3055 6.3148 1.8116 3.2066 3.2 134 4.7124
68.24 45.26 46.03 60.32 77. I 1 8 1.28 6.90 - 15.68 65.83 24.57 28.00 63. I7 74.66 77.38 11.13 82.23 40.86 50.12 54.81 88.54 91.26 77.16 24.07 -28.28 - 17.78 - 18.30
c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-61 0-62 H- I H-2 H-3 H-4 H-5
-0.7760 -0.1590 0.9330 0.4490 -0.1500 -0.7230 - 1.8980 0.3580 1.3120 1.5440 -1.2170 -0.0600 - 1.7860 -0.0210 -0.9450 1.8150 -0.2760 0.6280
3.3530 4.7 100 4.5940 3.7780 2.4440 1.6580 3.5690 5.2660 5.9020 3.4410 2.7080 0.6530 2. I 140 2.7260 5.3900 4. I100 4.3680 I .8290
1.6740 1.9820 3.0350 4.2270 3.7950 4.9550 0.8840 0.7780 3.4690 5.0760 2.8700 5.2910 5.4290 1.1760 2.3410 2.5920 4.8060 3.3190
3.4416 4.7127 4.6878 3.8046 2.4486 I 3088 4.0423 5.2782 6.0461 3.7715 2.9689 0.6558 2.7675 2.726 I 5.4722 4.4929 4.3767 1.9338
103.03 9 1.93 78.52 83.22 93.51 1 13.56 1 18.00 86.1 1 77.47 65.83 1 14.20 95.25 130.19 90.44 99.94 66.17 93.62 7 1.05
K W
-4.2850 -3.0480
-4.2850 1.4190
11.6750
6.0599 3.3621
-135.00 115.04
c-2 c-3 c-4 c-5 C-6 c-7 C-8 0-1 N-2 0-3 0-4 0-5 0-6 0-7 H- 1 H-2 H-3 H-4 H-5 H-61 H-62 H-N H-8 1 H-82 H-83 GlcA B
Ion
Water
c-1
423
7.4630
RENGASWAMI CHANDRASEKARAN
424
TABLE A24 Structure 34: Potassium Chondroitin 4-Sulfate
GalNAc4SO; A
C-1
c-2 c-3 c-4 c-5 C-6 c-7 C-8 0-1 N-2 0-3 0-4 0-5
0-6 0-7
s 0-s1 0-s2 033 H- I H-2 H-3 H-4 H-5 H-61 H-62 H-N H-8 1 H-82 H-83 GlcA B
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62 H- 1
0.473 1 -0.5992 -0.1770 0.1516 1.1364 1.351 I -1.9139 - I .9450 0.0209 -0.8271 - 1.2277 -1.0310 0.6542 1.9892 -2.8566 - 1.8443 -3.1109 -1.0718 -2.0865 1.4206 - 1.5504 0.7129 0.5930 2.1103 1.9868 0.3807 -0.0847 -2,0662 -2.7870 - 1.0022
- 1.9564 - I .7002 -2.3027 -3.7792 -3.9903 -5.4522 0.3565 1.8634 - 1.4752 -0.2446 -2.1420 -4.5201 -3.3685 -6.1461 -0.21 14 -5.0686 -4.3705 -4.8428 -6.4895 - 1.4952 -2.1511 - 1.7764 -4.1711 -3.5541 - 5.5409 -5.9335 0.2450 2.0469 2.3135 2.3148
1 1. I706 12.2227 13.5524 13.3775 12.2311 1 1.9063 1 1.9063 12.1672 9.9492 12.3532 14.5074 13.0861 11.0318 12.9806 11.3344 14.3519 14.4519 15.5567 14.1909 11.4871 1 1.9007 13.9272 14.3047 12.5003 11.0124 11.7147 12.8112 13.2443 1 1.6203 1 1.8230
2.0128 1 .8027 2.3095 3.7822 4.1490 5.6171 1.9468 2.6936 1.4753 0.8625 2.4689 4.6362 3.4314 6.4600 2.8644 5.3937 5.3646 4.9600 6.8167 2.0625 2.65 16 1.9141 4.2130 4.1334 5.8863 5.9457 0.2592 2.9084 3.6221 2.5225
-76.41 -109.41 -94.40 -87.70 -74.10 -76.08 169.45 136.23 -89.19 - 163.53 - 119.82 - 102.85 -79.01 - 72.07 - 175.77 - 109.99 - 125.44 - 102.48 - 107.82 -46.47 - 125.78 -68.13 -81.91 -59.30 -10.27 -86.33 109.07 135.27 140.30 113.41
1.5513 1.9640 1.0896 0.9900 0.6362 0.5906 2.4689 1.8836 1.640 1 0.0209 1.6209 1.4710 -0.3246 0.521 1
-0.4045 - 1.7743 -2.201 6 -1.1178 0.20 14 1.3620 0.0075 -2.7 168 -3.3906 - 1.4752 0.5262 1.3966 2.1993 -0.4427
6.2127 6.7318 7.9005 8.9665 8.2891 9.2580 5.2550 5.6686 8.4724 9.9492 7.2953 10.1463 9.0997 5.8268
1.6032 2.6468 2.4565 1.4932 0.6673 1.4845 2.4689 3.3059 3.7665 1.4753 1.7042 2.0284 2.223 1 0.6837
- 14.62 -42.10 -63.67 -48.47 17.56 66.56 0.17 -55.27 -64.19 -89.19 17.98 43.5 1 98.40 -40.35
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
425
TABLE A24 (conrinued)
H-? H-3 H-4 H-5
3.0159 0.0844 1.9652 -0.3522
Ion
K
Water
w- 1 w-2 w-3 w-4
- I .7363 -2.4356 -0.9980 0.1 169
7.0538 7.5202 9.4606 7.8144
3.4800 2.4371 2.2041 0.3711
-29.93 -88.01 -26.92 161.64
-2.9442
2.9 I67
0.0000
4.1443
135.21
1.3043 3.6780 -6.21 14 1.9832
4.7615 -2.9 I35 2.0150 -4.9169
1.2270 3.7504 -2.9648 0.9466
4.9369 4.6921 6.5301 5.3018
74.68 -38.38 162.03 -68.03
0.7036 0.9250 0.9176 2.3984 2.7830 4.2554 2.7156 3.8289 0.8719 1 SO09 1.1834 3.3147 2.1 194 4.9219 3.2346 4.4 159 4.9177 3.9925 5.6412 0.9445 2.0232 0.8870 2.8508 2.8468 4.801 1 4.5037 1.71 18
-140.13 158.57 - 143.33 -131.11 -116.44 -119.93 99.03 80.83 155.76 88.01 171.69 -153.44 - I3 1.92 - 106.79 119.04 - 150.36 - 165.64 - 137.89 - 144.30 -57.89 158.70 -68.99 - I 18.72 -93.95 -121.17 -131.46 56.29 (continued)
TABLE A25 Structure 35: Calcium Chondroitin 4-Sulfate
GalNAc4S0, A
C-1 c-2 c-3 c-4 c-5 C-6 c-7 c-8 0-1 N-2 0-3 0-4 0-5 0-6 0-7 S 0-s1 0-s2 0-S3 H- I H-2 H-3 H-4 H-5 H-6 1 H-62 H-N
-0.5400
-0.8610 -0.7360 - 1.5770 - 1.2390 -2.1230 -0.4260 0.6100 -0.7950 0.0520 -1.1710 -2.9650 -1.4160 - 1.4220 - 1 S700 -3.8380 -4.7640 -2.9620 -4.5810 0.5020 - I .8850 0.3 180 - 1.3700 -0.1960 -2.4850 -2.9820 0.9500
-0.45 10 0.3380 -0.5480 - 1.8070 -2.4920 -3.6880 2.6820 3.7800 0.3580 1SO00 0.1710 - 1.4820 - 1.5770 -4.7 120 2.8280 - 2.1 840 - 1.2200 -2.6770 -3.2920 -0.8000 0.7350 -0.8280 - 2.5000 -2.8400 -4.1080 -3.3750 1.4240
6.7500 8.0130 9.2420 9.0740 7.7540 7.4740 8.6360 8.6720 5.6510 8.1080 10.3980 9.0880 6.6620 6.7700 9.0340 10.2300 10.7920 I 1.2750 9.66 I0 6.7890 7.9490 9.3880 9.9020 7.7770 8.4240 6.8620 7.8080
426
RENGASWAMI CHANDRASEKARAN
TABLE A25 (continued) Group
GlcA B
z (A,
r (A)
1.4940 0.9030 0.1900
3.4320 4.0420 4.6650
9.2260 7.6440 9.1710
3.7431 4.1416 4.6689
66.48 77.41 87.67
0.3360 0.7200 -0.0680 0.0820 -0.2560 -0.0160 1.1710 0.4800 0.4040 -0.7950 0.5630 -0.9860 1.1230 -0.7280 1.7970 -1.1310 1.1 I70 - 1.3170
-0.1260 - 1.2620 - 1.1730 0.2 120 1.2850 2.6870 -0.1710 -2.5070 -2.1620 0.3580 1.1250 3.2050 3.1480 - 0.2 140 - 1.2080 -1.3710 0.3490 1.2030
1.6850 2.6230 3.9200 4.5360 3.5060 4.0240 0.5760 1.9740 4.8370 5.6510 2.3380 4.6160 3.7910 1.4190 2.8430 3.7180 4.8830 3.2260
0.3588 1.4529 1.1750 0.2273 1.3103 2.6870 1.1834 2.5525 2.1994 0.8719 1.2580 3.3532 3.3423 0.7588 2.1653 1.7773 1.1703 I .7837
-20.56 -60.29 -93.32 68.85 101.27 90.34 -8.31 -79.16 -79.42 155.76 63.41 107.10 70.37 - 163.62 -33.91 - 129.52 17.35 137.59
x
H-8 I H-82 H-83
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 I 0-62 H- 1 H-2 H-3 H-4 H-5
(A,
Y (A)
Atom
4 ("1
Ion
Ca
3.7120
2.6450
3.8870
4.5580
35.47
Water
w-1
3.7820 5.2270 3.3380 4.2740 2.8080 2.6950 3.7730
0.1620 3.9 100 1.5450 4.4540 4.8950 7.9720 -2.5240
3.8400 2.3550 6,0750 4.41 10 2.9310 0.8570 0.9300
3.7855 6.5276 3.6782 6.1729 5.6432 8.4152 4.5394
2.45 36.80 24.84 46.18 60.16 71.32 -33.78
w-2 w-3 w-4 w-5 W-6 w-7
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
427
TABLE A26 Structure 39: Keratan 6-Sulfate Group Gal6S0,- A
Atom
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 S
0-s1 0-s2 0-S3 GlcNAc6SO; B
c-1 c-2 c-3 c-4 c-5 C-6 c-7 c-8 0-I N-2 0-3 0-4 0-5 0-6 0-7 S
0-s1 042 043
x (A,
y
iA,
- 1.1950 -1.1520 - 1.6580 -3,0320 -2.9990 -4.3630 -0.8500 0.1810 - I .7370 -4.0040 -2.5320 -4.3050 -5.6960 -6.6230 -6.25 10 -5.4760
-0.4350 0.2730 -0.6470 -1.1960 - 1.8200 -2.2830 0.4810 0.6940 0.0750 -0.1490 -0.8620 -2.8870 - 3.4140 -2.3050 -4.4160 - 3.9980
1 1.4880 12.8360 13.9370 13.5750 12.1840 11.7180 10.5020 12.1030 15. I670 13.5810 11.2220 10.4270 9.8360 9.7200 10.7250 8.5270
1.2717 1.1839 1.7798 3.2594 3.5080 4.9242 0.9767 0.7 I72 1.7386 4.0068 2.6747 5.1834 6.6408 7.0126 7.6535 6.7802
- 160.00 166.67 - 158.68 - 158.47 - 148.75 - 152.38 150.50 75.38 177.53 - 177.87 -161.20 -146.15 - 149.06 - 160.81 - 144.76 -143.87
0.8620 0.01 30 -0.8640 -0.01 60 0.8490 1.7990 -0.6290 - 1.5350 1.7370 -0.8120 - 1.5480 -0.8500 1.6540 2.5810 0.1830 4.0380 4.8140 3.9180 4.7040
0.3 I50 -0.8880 -0.5530 0.0000 1.1510 1.6700 -2.5620 -2.8500 -0.0750 - 1.3020 - 1.7290 0.48 I0 0.7200 2.7640 -3.3640 2.9200 1.7240 3.1090 4.0670
6.7230 7.1 150 8.3 120 9.4500 8.9500 10.0080 5.4260 4.2530 5.7170 5.9590 8.7480 10.5020 7.8410 9.5280 5.8580 10.1700 9.9050 1 1.6030 9.5850
0.9178 0.888 I 1.0258 0.0160 1.4302 2.4546 2.6381 3.2371 1.7386 1 s345 2.3207 0.9767 1.8039 3.7817 3.3690 4.9832 5.1134 5.0017 6.2 184
20.07 -89.16 - 147.38 180.00 53.59 42.87 - 103.79 - 118.31 -2.41 -121.95 -131.84 150.50 23.52 46.96 - 86.89 35.87 19.70 38.43 40.85
RENGASWAMI CHANDRASEKARAN
428
TABLEA27 Structure 41: Potassium Cellan
Glc A
c-I c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6
H- 1 H-2 H-3 H-4 H-5 H-61 H-62 GlcA B
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 I 0-62 H- 1 H-2 H-3 H-4 H-5
Glc C
C- I c-2 c-3 c-4
c-5
- 1.5238 - 1.3436 - 1.8743 -3.3144 - 3.4166 -4.843 1 - I. I462 0.0346 -1.7971 - 3.7658 -2.9059 -5.2987 -0.9384 - 1.8830 - 1.2504 -3.96 17 -2.8387 -5.5013 -4.912 I
-3.0629 -2.5862 -3.6241 -3.9777 -4.3775 -4.6325 -2.0333 -2.3248 -3.1 124 -5.0674 -3.3316 -5.9232 -3.9809 -1.6381 -4.5262 -3.1091 -5.2978 -3.8612 -4.5446
15.0225 16.4577 17.4347 17.0874 15.6193 15.181 1 14.1700 16.6970 18.7666 17.8888 14.7783 15.5845 14.8659 16.5998 17.3516 17.2781 15.4486 15.6077 14.0868
3.4210 2.9144 4.0801 5.1776 5.5530 6.7019 2.3341 2.3251 3.5940 6.3 135 4.4208 7.9474 4.0900 2.4958 4.6958 5.0360 6.0104 6.72 I 1 6.6919
- 116.45 -117.45 - 117.35 - 129.80 - 127.97 - 136.27 - 119.41 -89.15 - 120.00 - 126.62 -131.10 -131.82 - 103.26 - 138.98 - 105.44 - 141.88 -118.18 - 144.94 - 137.23
0.6335 -0.5206 - 1.3409 -0.4284 0.7455 1.7534 1.4170 - 1.3211 -2.3817 - 1.1462 1.4554 1.6120 2.6502 0.2332 -0.1231 - 1.8057 -0.0476 0.3733
- 1.6607 -2.6495 -2.3633 -2.4098 - 1.4556 -1.5349 -2.0132 -2.5566 -3.3345 -2.0333 - 1.7648 -2.4649 -0.6644 -0.6390 -3.6743 - 1.3700 -3.4353 -0.4217
10.4311 10.5299 1 1.7783 12.9968 12.8049 13.9323 9.3396 9.3571 11.9011 14.1700 11.5955 14.7555 13.9541 10.3548 10.5710 11.6921 13.1 130 12.7536
1.7774 2.7002 2.7 172 2.4476 1.6354 2.3303 2.4619 2.8778 4.0977 2.3341 2.2875 2.9452 2.7322 0.6802 3.6764 2.2666 3.4356 0.5632
-69.12 -101.12 - 1 19.57 - 100.08 -62.88 -41.20 -54.86 - 117.33 - 125.54 - 119.41 -50.49 -56.82 - 14.07 -69.95 -91.92 -142.81 -90.79 -48.49
1.9361 1.5740 1.8374 1.0427 1.3191
-0.8599 0.2734 -0.1857 - 1.4555 -2.5084
5.4297 6.3805 7.8065 8.08 I8 7.0138
2. I 185 1.5976 1.8468 1.7904 2.8341
-23.95 9.85 - 5.77 -54.38 -62.26
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
429
TABLE A27 (continued)
C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
0.4326 1.6783 2.3368 1.4544 1.4170 1.0803 -0.9514 2.9840 0.5 139 2.9124 -0.0283 2.3658 0.6754 0.6384
-3.7278 -0.45 12 1.4279 0.8440 -2.0132 - 1.9709 -3.3878 -1.1576 0.5365 -0.3790 - 1.2050 -2.8388 -4.4499 -4.2238
7.1524 4.1275 6.0483 8.7201 9.3396 5.7038 7.0794 5.5823 6.2507 7.9370 8.0957 7.0867 6.3588 8.1124
3.7528 1.7379 2.7385 1.6816 2.4619 2.2476 3.5189 3.2007 0.7429 2.9370 1.2053 3.6954 4.5009 4.2718
3 1.43 30.13 -54.86 -61.27 - 105.69 -21.20 46.23 -7.41 -91.35 -50.19 -81.37 -81.41
H-2 H-3 H -4 H-5 H-6 1 H-62 H-63
4.3084 3.4455 2.2443 2.7759 3.6398 4.2913 3.5938 4.2562 1.4487 1.6783 4.7152 5.1968 3.1079 1.6555 3.3962 3.0216 3.5449 5.1 129 4.6887
0.6087 1.6989 1.0652 0. I269 -0.9495 -1.9015 0.0000 2.4148 2.1206 -0.4512 -0.33 16 1.0524 2.3923 0.5008 0.7035 - 1.532I -2.6254 -2.4383 - 1.3315
1.0438 1.6666 2.3532 3.4272 2.7540 3.7395 0.0000 2.5895 2.857 1 4.1275 2.0258 0.5706 0.8822 1.6152 4.1291 2.0552 4.0984 3.2425 4.5922
4.3512 3.8416 2.4843 2.7788 3.7616 4.6937 3.5938 4.8935 2.5682 1.7379 4.7268 5.3023 3.9220 1.7296 3.4683 3.3878 4.41 12 5.6645 4.8741
8.04 26.25 25.39 2.62 - 14.62 -23.90 0.00 29.57 55.66 - 15.05 -4.02 1 1.45 37.59 16.83 11.70 -26.89 -36.52 -25.50 - 15.85
Ion
K
0.5772
-3.0753
17.0233
3.1290
-79.37
Water
W
0.2932
-3.6603
10.1826
3.6720
-85.42
Rha D
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5
H- 1
-83.38 - 15.05
TABLE A28 Structure 42: Potassium Native Gellan
Glc A
c-1 c-2 c-3 c-4 c-5 C-6 c-7 c-8 c-9 c-I0 c-I1 0-1 0-2 0-3 0-4 0-5 0-6 0-7 0-9 0-10 0-11 H- 1 H-2 H-3 H-4 H-5 H-61 H-62 H-81 H-82 H-83 H-10 H-111 H-I 12
GlcA B
c-1 c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0 - 6I
- 1.4394 -1.2901 - 1.7942 -3.2305 -3.3294 -4.7555 -6.5204 -7.1180 0.9540 2.2721 2.1357 - 1.0528 0.0740 -1.7150 -3.6631 -2.8171 -5.2151 -7.1274 0.7272 2.7042 2.5585 -0.8492 - I .8687 - 1.1548 -3.8893 -2.7510 -5.421 1 -4.8334 -6.7553 -8.2 I49 -6.8194 3.0434 1.0839 2.7586
-3.1009 -2.5189 -3.5305 -3.92 I7 -4.3959 -4.6732 -6.1790 -6.2710 -3.1264 -2.5817 -2.1477 -2.1368 -2.1849 -2.9706 -4.9758 -3.3920 -5.9634 -6.2837 -4.3 178 - 1.4585 -3.1901 -4.0264 - 1.5859 -4.4238 -3.0540 -5.3232 - 3.9099 -4.5915 -7.1836 -6.3058 -5.3895 -3.3635 - 1.9064 - 1.2583
15.2172 16.6166 17.6344 17.3120 15.8659 15.4387 15.9033 14.5186 17.1526 17.6848 19.1299 14.2951 16.8444 18.9467 18.169 I 14.9760 15.8386 16.9565 17.0212 16.9334 20.01 13 15.1370 16.6890 17.5780 17.4620 15.7430 15.8670 14.3450 14.0220 14.5940 13.9310 17.6230 19.3430 19.3060
3.4187 2.8301 3.9603 5.0809 5.5144 6.6673 8.983 1 9.4864 3.2687 3.4391 3.0288 2.3821 2.1862 3.4301 6.1788 4.4093 7.9221 9.5018 4.3786 3.0725 4.0893 4.1 150 2.4510 4.5720 4.9450 5.9920 6.6840 6.6666 9.8610 10.3560 8.6920 4.5360 2.1930 3.0320
- 114.90
0.3679 -0.5915 - 1.3425 -0.3582 0.6054 I .6788 1.1173 - 1.4942 -2.1415 - 1.0528 1.2783 1.9705
-2.1591 -3.2873 -2.9555 -2.61 15 - 1.5267 -1.2161 -2.55 13 -3.4948 -4.0738 -2.1368 - 1.9542 -2.0954
10.3981 10.7534 12.0339 13.1439 12.6746 13.6967 9.2963 9.6732 12.4247 14.295 1 11.4802 14.5359
2.1902 3.3401 3.2461 2.6360 1.6423 2.0730 2.7852 3.8008 4.6024 2.382 1 2.3351 2.8764
-80.33 - 100.20 - 114.43 -97.81 -68.37 -35.92 -66.35 - 113.15 - 117.73 - 1 16.23 -56.81 -46.76
430
- 117.12 -116.94 - 129.48 -127.14 - 135.50 - 136.54 - 138.62 -73.03 -48.65 -45.16 - 116.23 -88.06 - 120.00 - 126.36 - 129.7 1 -131.17 - 138.60 -80.44 -28.34 -51.27 -101.91 - 139.68 - 104.63 - 141.86 - 1 17.33 - 144.20 - 136.47 - 133.24 - 142.49 -141.68 -47.86 -60.38 -24.52
TABLE A28 (continued)
Group
Glc C
Atom 0-62 H- 1 H-2 H-3 H-4 H-5
2.2620 -0.2019 -0.0265 -2.0113 0.2089 0.0457
-0.1106 -1.2356 -4.2209 -2.1003 -3.5168 -0.6013
13.7063 10.2180 10.8870 I 1.8560 13.4050 12.4730
2.2647 1.2520 4.2210 2.9080 3.5230 0.6030
-2.80 -99.28 -90.36 - 133.76 -86.60 -85.65
c-1
1.8675 1.5683 1.6999 0.8232 1.0752 0.1073 1.6726 2.4593 1.3136 1.1173 0.9261 - 1.2407 2.8872 0.5480 2.7490 -0.2313 2.0943 0.3796 0.1917
-1.2211 -0.1 199 -0.67 I3 - 1.9042 -2.9050 -4.0692 -0.7186 0.9687 0.3295 -2.55 13 -2.2796 -3.6424 - 1.6044 0.2587 -0.9391 - 1.5913 -3.3077 -4.7910 -4.5940
5.4645 6.4732 7.8845 8.0601 6.9374 6.9646 4. I843 6.2589 8.8283 9.2963 5.6534 6.772 I 5.6200 6.31 10 8.0770 8.0520 7.0270 6.1800 7.9280
2.2313 1.5729 1.8277 2.0745 3.0976 4.0706 1.8204 2.6432 1.3543 2.7852 2.4605 3.8479 3.3030 0.6060 2.9050 1.6080 3.9150 4.8060 4.5980
-33.18 -4.37 -21.55 -66.62 -69.69 -88.49 -23.25 21.50 14.08 -66.35 -67.89 - 108.81 -29.06 25.27 - 18.86 -98.27 -57.66 -85.47 -87.61
4.3346 3.8705 2.5832 2.85 17 3.2795 3.6145 3.4300 4.9 130 2.2073 1.6726 4.4696 5.2992 3.7005 1.7922 3.6664 2.4756 2.7134 4.3952 3.9787
0.1392 1.2883 0.9077 -0.3582 -1.471 1 -2.7775 0.0000 1.5642 2.0148 -0.7186 - 1.0599 0.3966 2.1841 0.7216 -0.1626 - 1.6535 -3.4051 -3.3048 -2.5690
1.0643 1.9528 2.6697 3.4708 2.5029 3.1978 0.0000 2.8793 3.4659 4.1843 1.8075 0.6010 1.3370 1.9290 4.1830 1.7750 3.2520 2.6300 4.2150
4.3368 4.0793 2.7380 2.8741 3.5943 4.5584 3.4300 5.1560 2.9886 1.8204 4.5935 5.3140 4.2970 1.9320 3.6700 2.9770 4.3540 5.4990 4.7360
I .84 18.41 19.36 -7.16 -24.16 -37.54 0.00 17.66 42.39 -23.25 - 13.34 4.28 30.55 21.93 -2.54 -33.74 -51.45 -36.94 -32.85
2.0561
11.2010
2.0800
98.69
c-2 C-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
Rha D
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 H-63
Ion
K
-0.3143
43 I
RENGASWAMI CHANDRASEKARAN
432
TABLE A29 Structure 43: Calcium Welan
Glc A
c-1 c-2 c-3 c-4 c-5 C-6 c-7 c-8 0-1 0-2 0-3 0-4 0-5 0-6 0-7 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 H-8 1 H-82 H-83
GlcA B
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-61 0-62 H- 1 H-2 H-3 H-4 H-5
- 1.0853 -0.7168 - 1.7505 -3.1426 -3.4054 -4.7279 1.1465 2.2173 -0.1872 0.5776 - 1.4426 -4.1336 -2.3851 -5.8354 0.8246 - 1.0878 -0.6639 -1.7134 -3.2206 -3.4 176 -4.7987 -4.7708 3.0564 2.5750 1.8004
-2.6319 -2.3143 -2.8937 - 2.4 127 -2.7025 -2.1423 -2.5276 -3.5330 - 1.9798 -2.8348 -2.4988 -3.0788 -2. I099 -2.8534 - 1.5560 -3.7221 - 1.2237 -3.9904 - 1.3306 -3.7902 - 1.0804 -2.1907 -3.4394 -3.3427 -4.5493
15.3916 16.8348 17.7884 17.4007 15.9267 15.4479 18.27I7 18.6263 14.5565 17.1151 19.1267 18.1800 15.1082 15.9993 18.9355 15.2448 16.9684 17.7118 17.5826 15.7633 15.7260 14.3499 17.9212 19.6490 18.5670
2.8469 2.4228 3.3820 3.9619 4.3474 5.1906 2.7755 4.1712 1.9886 2.8930 2.8853 5.1542 3.1844 6.4957 1.7610 3.8778 1.3922 4.3427 3.4847 5.1035 4.9 I88 5.2497 4.60 12 4.2195 4.8926
- 1 12.41 -107.21 -121.17 - 142.49 -141.56 - 155.62 -65.60 -57.89 -95.40 -78.48 - 120.00 - 143.32 - 138.50 - 153.94 -62.08 - 106.29 - 118.48 -113.24 - 157.55 - 132.04 - 167.31 - 155.34 -48.37 -52.39 -68.41
0.6737 -0.6899 - 1.0434 0.0555 1.4083 2.5613 1.0081 - 1.6660 -2.2588 -0.1872 1.6593 2.4734 3.5132 0.6426 -0.6663 -1.1450 0.0707 1.4227
-2.2172 -2.7452 -2.2043 -2.58 12 -2.1069 -2.5624 -2.7991 -2.3538 -2.8038 - 1.9798 -2.6245 -3.701 I - 1.765I -1.1187 -3.8447 -1.1101 -3.6757 - 1.0075
10.4993 10.9249 12.3018 13.2866 12.7663 13.6360 9.2832 9.9663 12.7549 14.5565 1 1.4506 14.1441 13.7796 10.4508 10.9491 12.251 1 13.3959 12.7309
2.3173 2.8306 2.4388 2.5818 2.5342 3.6230 2.975 1 2.8837 3.6005 1.9886 3.1050 4.4515 3.9317 1.2901 3.9020 1.5948 3.6764 1.7433
-73.10 -104.1 1 - 115.33 -88.77 -56.24 -45.01 -70.19 - 125.29 - 128.86 -95.40 -57.70 -56.25 -26.68 -60.13 -99.83 - 135.89 -88.90 -35.31
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
433
TABLE A29 (continued)
Glc C
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H2 H-3 H-4 H-5 H-6 1 H-62
Rha D
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 H-63
Man E
c-1 c-2 c-3 c-4 c-5
1.4988 1.5328 I .775 1 0.6925 0.5809 -0.5934 I .2635 2.5498 1.7585 1.0081 0.3949 - 1.8010 2.4335 0.5761 2.7649 -0.2651 I .4983 -0.3822 -0.7221
- 1.4889 -0.3846 -1.0168 -2.0515 - 3.04 17 -3.9853 -0.9190 0.5522 -0.0044 -2.7991 -2.3489 -3.4 127 -2.0680 0.1583 - 1.4968 - 1.5298 -3.6464 -4.9225 -4.2437
5.4230 6.4713 7.8333 8.1 106 6.9562 7.1073 4. I783 6. I349 8.8416 9.2832 5.7122 6.6070 5.4558 6.4634 7.8441 8.2548 6.901 6 6.5715 8.1687
2.1 126 1.5803 2.0457 2.1652 3.0967 4.0292 1.5624 2.6089 1.7585 2.975 1 2.3819 3.8588 3.1935 0.5975 3.1440 1.5526 3.9422 4.9373 4.3047
-44.81 - 14.08 -29.80 -71.35 -79.19 -98.47 -36.03 12.22 -0.14 -70.19 -80.46 -117.82 -40.36 15.37 -28.43 -99.83 -67.66 -94.44 -99.66
3.8234 3.3521 2.0826 2.4172 2.8878 3.3255 2.8854 4.4029 1.6577 1.2635 4.0296 4.7585 3.1572 1.3008 3.2299 2.0763 2.4460 4.0299 3.8 180
0.141 1 1,2340 0.7806 -0.4893 - 1.5570 -2.8496 0.0000 1.4822 1.8519 -0.9190 - 1.0775 0.444 1 2. I556 0.5759 -0.2728 - 1.7799 - 3.4846 -3.3792 -2.6225
1.0349 1.9859 2.6923 3.4617 2.4634 3.1264 0.0000 2.9109 3.5124 4.1783 I .7323 0.54 13 1.4179 1.9462 4.1707 1.7550 3.3085 2.4682 4.0834
3.8260 3.5720 2.2241 2.4662 3.2808 4.3794 2.8854 4.6457 2.4855 1.5624 4.1712 4.7792 3.8229 1.4226 3.2414 2.7348 4.2574 5.2592 4.6319
2.1 1 20.2 I 20.55 -11.44 -28.33 -40.59 0.00 18.61 48.17 -36.03 - 14.97 5.33 34.32 23.88 -4.83 -40.60 -54.93 -39.98 -34.48
2.8549 2.9646 3.3215 4.6570 4.5012
0.8722 1.4888 0.4057 -0.1880 -0.7916
8.8685 10.2579 I 1.2658 10.8408 9.4370
2.9852 3.3174 3.3462 4.6608 4.5703
16.99 26.67 6.96 -2.3 I -9.97 (continued)
434
RENGASWAMI CHANDRASEKARAN
TABLE A29 (continued) Group
Ion
Atom
x iA)
C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 I H-62 H-63
5.7961 1.7585 3.9628 3.3453 5.0284 4.0636 5.5595 2.6260 2.0056 2.5709 5.4097 3.7543 6.3820 6.3643 5.5700
Ca
14.8I32
y
iA)
z
6,
r (A)
4J (7 - 13.06
- 1,3449 -0.0044 2.5000 1.0160 - 1.2095 0.2 194 -2.2738 I .6505 1.9545 -0.3973 0.6135 - 1.5986 -0.5266 - 1.8387 -2.0545
8.8728 8.8416 10.2025 12.5411 11.7615 8.5127 7.8157 8.1257 10.5292 1 1.2224 10.8096 9.4655 8.4287 9.6748 8.0632
5.9501 1.7585 4.6855 3.4962 5.1718 4.0695 6.0065 3.1016 2.8005 2.6014 5.4444 4.0805 6.4037 6.6246 5.9368
-0.14 32.25 16.89 - 13.53 3.09 -22.24 32.15 44.26 -8.78 6.47 -23.06 -4.72 -16.11 -20.25
S.7249
11.9002
15.8810
21.13
TABLE A30 Structure 46:E. coli M41 Capsular Polysaccharide Group Man A
Atom
c-I c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 I H-62
x (A,
1.6390 2.6360 4.0620 4.2690 3.1920 3.2450 1.7720 2.4080 4.9790 5.5450 1.8910 2.1530 0.6160 2.4730 4.2610 4.2230 3.3060 4.1810 3.2050
Y
6,
2.1920 3.0430 2.6570 1.1590 0.3840 -1.1050 2.4920 2.8810 3.3740 0.7690 0.8260 - 1.5340 2.4440 4.1060 2.9310 0.9090 0.5500 - 1.3480
- 1.6550
z (A,
r (A)
4J (7
14.1500 14.9250 14.5620 14.7430 13.9920 14.2660 12.7730 16.3200 15.3900 14.2390 14.4110 15.0780 14.4670 14.6900 13.5150 15.8140 12.91 10 14.7900 13.3140
2.7370 4.0260 4.8.538 4,4235 3.2150 3.4280 3.0578 3.7548 6.0145 5.5981 2.0635 2.6436 2.5204 4.7932 5.1717 4.3197 3.3514 4.3929 3.6071
53.21 49.10 33.19 15.19 6.86 - 18.80 54.58 50.1 1 34.12 7.90 23.60 - 35.47 75.85 58.94 34.52 12.15 9.45 - 17.87 -27.31
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
435
TABLE A30 (c,unrinued)
Glc B
c-1
0.1460 1.2590 0.6990 -0.1 I80 -1.1580 - 1.9270 0.7200 1.9170 1.7720 -0.7910 -0.5200 -3.1990 -0.5740 2.0090 0.0590 0.5520 -1.8810 -2.0910 -1.3510
1.0470 1.3670 2.0790 3.2930 2.8910 4.0750 0.5210 0. I630 2.4920 3.8560 2.2550 4.2 180 0.3590 2.0090 1.3870 4.0550 2. I960 3.9400 4.9970
9.7140 10.7030 1 1.9240 11.5010 10.4610 9.9150 8.5630 1 I .0770 12,7730 12.6240 9.3430 10.5460 10.1820 10.2160 12.4920 I 1.0740 10.9150 8.8360 10.0860
1.0571 1.8584 2.1934 3.295 1 3.1143 4.5077 0.8887 1.9239 3.0578 3.9363 2.3142 5.2939 0.6770 2.8412 1.3883 4.0924 2.8915 4.4605 5.1764
82.06 47.36 7 1.42 92.05 11 1.83 115.31 35.89 4.86 54.58 101.59 102.99 127.18 147.98 45.00 87.56 82.25 130.58 117.96 105.13
-0.9800 -0.2450 -0.0890 0.5570 -0.2020 0.4580 -0.9820 -0.9600 0.7200 0.54 I0 -0.2660 -0.1570 1.5350 - 1.9940 0.7480 - 1.0760 1.6020 -1.2210
-0.8820 -0.8850 0.5330 1.4200 1.3060 2.0770 -2.1770 - 1.6930 0.5210 2.7830 -0.0660 3.1000 1.5930 -0.4790 -1.3410 0.9380 1.1110 1.6990
5.5250 6.8.590 7.3850 6.3280 5.01 10 3.8880 5.0220 7.7880 8.5630 6.7470 4.5940 3.5150 3.4760 5.6650 6.7300 7.6500 6.1780 5.1390
1.3185 0.9183 0.5404 1.5253 1.3215 2. I269 2.3882 1.9462 0.8887 2.8351 0.2741 3.1040 2.2122 2.0507 1.5355 1.4275 1.9495 2.0922
- 138.01
c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6I 0-62 H- 1 H-2 H-3 H-4 H-5
c-I
- 1.6080
-3.8640
c-2 c-3 c-4
- 1.6670 - 1.0320 0.3750 0.3540 1.7420 -2.4080
- 3.6420
1.7280 3.2340 3.6000 3.0250 1.5310 0.9290 1.1000
4.1852 4.0054 2.5291 2.2465 2.5418 3.1 163 3.7548
c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 GlcA C
Gal D
c-1
c-5 C-6 0-1
-2.3090 -2.2150 -2.5170 -2.5840 -2.8810
- 105.47
99.48 68.58 98.79 77.56 - 114.28 - 119.56 35.89 79.00 - 166.07 92.90 46.06 - 166.49 -60.85 138.92 34.74 125.70 - 1 12.59 - 1 14.59 - 114.08
-80.39 -81.99 - 56.0 1 - 129.89 (continued)
436
RENGASWAMI CHANDRASEKARAN
TABLE A30 (continued)
Man E
0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-61 H-62
-3.0230 -0.9820 1.2380 -0.2630 1.7000 -2.0180 - 1.1340 - 1.6470 0.7710 -0.2130 2.2500 2.3190
- 3.69 10 -2.1770 -3.1520 -3.7930 -2.6140 -4.8560 -4.4560 - 1.4880 - 1.2020 - 1.7340 -3.4940 - 1.7000
3.6640 5.0220 3.6670 1.3000 -0.4970 1.4870 3.7460 3.2020 3.1900 1.0060 I .2790 1.2390
4.77 10 2.3882 3.3864 3.8021 3.1182 5.2586 4.5980 2.2 196 1.4280 1.7470 4.1558 2.8754
- 129.32 - 114.28 -68.56 -93.97 -56.96 -112.57 - 104.28 - 137.90 -57.32 -97.00 -57.22 -36.24
c-1
1.7950 1.5880 0.7260 1.31 10 1.5500 2.2670 0.5410 2.8540 0.6500 0.4 160 2.3720 3.6490 2.4660 1.0990 -0.2930 2.2630 0.5930 1.8030 2.1940
3.3650 4.41 10 5.5530 6.1200 5.0010 5.4780 2.7830 4.8910 6.5820 7.0680 3.9810 5.7340 2.5770 3.9460 5.1860 6.6250 4.5620 6.4100 4.7100
7.0510 8.1380 7.6220 6.3350 5.3270 4.0820 6.7470 8.5760 8.6100 5.7570 5.9170 4.3320 7.4220 9.0070 7.4310 6.5560 5.0090 3.7260 3.2990
3.8138 4.6881 5.6003 6.2588 5.2357 5.9286 2.835 1 5.6628 6.6140 7.0802 4.6341 6.7966 3.5668 4.0962 5.1943 7.0008 4.6004 6.6587 5.1959
61.92 70.20 82.55 77.91 72.78 67.52 79.00 59.74 84.36 86.63 59.21 57.53 46.26 74.44 93.23 71.14 82.59 74.29 65.02
3.1700 4.67 10 5.0910 4.6040 3.1080 2.5920 4.4150 5.2060 4.7 100 2.8540 5.0100 6.5150 4.8320 2.8280
4.6770 4.4380 4.3400 5.5580 5.7600 7.0240 6.8440 7.9830 6.8140 4.8910 3.2490 4.2540 5.6080 5.8670
9.91 10 10.0200 11.4780 12.2520 12.0290 12.6820 14.2440 13.5980 15.6940 8.5760 9.3150 1 1.5620 13.6580 10.6250
5.6501 6.443 1 6.6898 7.2172 6.5450 7.4870 8.1445 9.5305 8.2834 5.6628 5.97 13 7.7809 7.4026 6.5 130
55.87 43.53 40.45 50.36 61.65 69.74 57.17 56.89 55.35 59.74 32.96 33.14 49.25 64.27
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 Glc4.6-Pyr F
C- I c-2 c-3 c-4 c-5 C-6 c-7 C-8 c-9 0-1 0-2 0-3 0-4 0-5
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
437
TABLE A30 (continued)
3.0120 4.9570 6.0010 2.6300 5.2100 4.6640 5.1490 2.5560 1.4930 2.9980 4.3720 4.1840 5.7940
0-6 0-81 0-82 H- I H-2 H-3 H-4 H-5 H-6 1 H-62 H-9 I H-92 H-93
7.0380 8.1780 8.5730 3.8220 5.2660 3.4290 6.45 I0 4.9060 7.0420 7.9010 7.7530 5.9670 6.7000
14.0460 12.3880 14.3610 10.3430 9.5370 11.9230 11.9120 12.4500 12.6300 12.1570 16.IS70 16.1590 15.8460
7.6554 9.5630 10.4646 4.6395 7.4078 5.7889 8.2539 5.53 19 7.1985 8.4507 8.9008 7.2877 8.8578
66.83 58.78 55.01 55.47 45.31 36.32 5 I .40 62.48 78.03 69.22 60.58 54.96 49. I5
TABLE A3 1 Structure 47: Rhizobium trifolii Capsular Polysaccharide
Group Glc A
Atom
c-1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H-1 H-2 H-3 H-4 H-5 H-6 1 H-62
Man B
c-1 c-2 c-3 c-4 c-5
x
(A)
Y
(A,
3.5180 4.6209 4.0789 2.8580 1.8401 0.6548 3.0133 5.6817 5.0915 2.2397 2.448 1 -0.3494 3.9174 5.0331 3.7999 3.1796 1.463I 0.2239 0.9933
0.0974 0.2909 0.0866 0.9674 0.7597 1.6954 - 1. I897 -0.6185 0.4082 0.6439 1.0040 1.1796 0.2961 1.3068 -0.9687 2.0193 -0.273 1 1.8590 2.6749
6.1868 7.2191 8.6255 8.8564 7.7400 7.8486 6.3204 6.9500 9.5809 10.1000 6.4622 8.7214 5.1814 7.1294 8.7613 8.8692 7.7748 6.8498 8.2172
3.5193 4.6300 4.0798 3.0173 1.9907 1.8175 3.2397 5.7153 5.1078 2.3304 2.6460 1.2302 3.9286 5.2000 3.9214 3.7666 1.4884 1.8724 2.8534
1.59 3.60 I .22 18.70 22.43 68.88 -21.55 -6.21 4.58 16.04 22.30 106.50 4.32 14.56 - 14.30 32.42 - 10.57 83.13 69.63
-0.0578 0.9224 2.0426 2.7010 1.6432
-2.9134 -2.3594 - 1.6002 -2.4810 -3.0493
5.0244 6.0500 5.3556 4.3019 3.3619
2.9140 2.5333 2.5948 3.6675 3.4639
-91.14 -68.65 -38.08 -42.57 -61.68 (continued)
438
RENGASWAMI CHANDRASEKARAN
TABLE A3 1 (continued) z (A,
r (A,
4J(")
-4.0285 - 1.8509 -3.4302 - I . I897 - 1.7243 -3.7580 -4.4061 -3.4957 - 1.6848 -0.7129 -3.3054 -2.2284 -3.5675 -4.9366
2.3600 4.2943 6.8296 6.3204 3.5346 4.1082 1.3766 5.5388 6.7378 4.8712 4.7954 2.8032 1.8458 2.8839
4.5984 1.938I 3.7212 3.2397 4.0232 3.8124 4.5813 3.5944 1.7297 1.7597 4.6261 2.5168 4.7089 5.5564
-61.17 - 107.25 -67.19 -21.55 -25.38 -80.31 -74.10 - 103.46 -76.92 -23.90 -45.60 -62.30 -49.25 -62.68
-2.4443 - 1.3122 - 1.5649 -2.9495 -4.0031 -5.3855 -2.2397 -0.0823 -0.5748 -3.0070 - 3.6872 -5.4989 -2.4782 - 1.2264 - 1.4974 -3.1692 -4.03 15 -6.1344 -5.6096
- 1.5274 - 1.3468 -2.1637 - 1.8628 -2.0251 - 1.6391 -0.6438 - 1.7280 - 1.8509 -0.5259 -1.1783 -0.2327 -2.5774 -0.2836 -3.2299 -2.5530 -3.0742 - 1.9596 -2.1714
1.0520 2.0548 3.3 I26 3.871 1 2.7806 3.2624 0.0000 1.4492 4.2943 4.3638 1.6646 3.4757 0.7258 2.3235 3.0505 4.6989 2.45 12 2.5231 4.1985
2.8823 1.8804 2.6703 3.4885 4.4862 5.6294 2.3304 I .7300 1.9381 3.0526 3.8709 5.5038 3.5755 1.2588 3.5601 4.0696 5.0699 6.4398 6.0152
- 148.00 - 134.26 - 125.88 - 147.73 - 153.17 - 163.07 - 163.96 -92.73 - 107.25 - 170.08 - 162.28 - 177.58 - 133.88 - 166.98 - 1 14.87 -141.15 - 142.67 - 162.28 - 158.84
6.9710 7.8813 7.8610 8.1782 7.2659 7.6190 5.68 17 7.4628 8.8226 9.5325 7.3851 7.3912
-0.1602 -0.6906 -2.21 13 -2.7645 -2.1273 -2.5610 -0.6185 -0.1616 -2.6902 -2.4852 -0.6970 -3.9558
7.1890 6.0893 6.0676 7.4506 8.4933 9.9002 6.9500 4.8363 5.1254 7.7991 8.4469 10.0977
6.9728 7.9115 8.1661 8.6328 7.5709 8.0379 5.7153 7.4645 9.2236 9.85 11 7.4179 8.3832
- I .32 -5.01 - 15.71 - 18.68 - 16.32 - 18.58 -6.21 -1.24 - 16.96 - 14.61 -5.39 -28.16
Atom
x (A,
C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
2.2174 -0.5748 1.4426 3.0133 3.6349 0.6418 1.2548 -0.8364 0.3914 1.6088 3.2365 1.1698 3.0736 2.5502
Gal C
C- 1 c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5 0-6 H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62
Gal D
c-1
Group
c-2 c-3 c-4 c-5 C-6 0-1 0-2 0-3 0-4 0-5
0-6
Y
(A,
POLYSACCHARIDE HELICES IN ORIENTED FIBERS
439
TABLE A3 I (continued)
H- 1 H-2 H-3 H-4 H-5 H-6 1 H-62 Gal E
Gal F
6.9657 8.9093 6.8666 8.03 I9 6.2232 8.6754 6.9650
0.9385 -0.3398 -2.5604 -3.8548 -2.4153 -2.3297 -2.0447
7.2424 6.2630 5.7525 7.4520 8.2935 10.1012 10.6184
7.0286 8.9158 7.3284 8.9090 6.6755 8.9828 7.2589
7.67 -2.18 - 20.45 -25.64 -21.21 - 15.03 - 16.36
c-I
- 1.4423
c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H-1 H-2 H-3 H -4 H-5 H-6 I H-62
- 1.9966 -3.278 I -4.2724 -3.6133 -4.5257 -0.3494 -1.0150 -3.8523 -4.7315 -2.4282 -4.5543 -1.1372 -2.2020 -3.0475 -5.1372 - 3.3478 -4.1871 - 5.5440
0.5685 -0.4765 - 1.0797 0.0201 1.0607 2.2379 1.1796 - 1.4837 -1.9591 0.6683 I .5794 3.1508 0.1387 -0.008 1 - 1.6648 -0.4182 0.5986 2.7627 1.8740
8.1203 9.0797 8.5252 8.1770 7.2778 7.0056 8.7214 9.2964 9.4941 9.3613 7.9012 8.1021 7.1548 10.0536 7.6228 7.6575 6.3 156 6.1001 6.8046
1.5503 2.0527 3.4513 4.2724 3.7658 5.0488 1.2302 1.7977 4.3218 4.7785 2.8967 5.5380 1.1456 2.2020 3.4726 5.1542 3.4009 5.0164 5.8522
158.49 - 166.58 -161.77 179.73 163.64 153.69 106.50 - 124.38 - 153.04 171.96 146.96 145.32 173.05 - 179.79 -151.35 -175.35 169.86 146.58 161.32
c-I
-6.1076 -6.4935 -7.9713 -8.3 154 -7.8302 -8.0441 -4.7315 -6. I856 -8.2827 -7.6923 -6.4228 -6.99 I2 -6.61 16 -5.8936 -8.5732 -9.4049 -8.3772 -8.1 102 -9.0041
0.7387 -0.1861 -0.0394 1.4233 2.2820 3.7591 0.6683 - 1.5293 -0.8111 1.8844 2.087 I 4.3197 0.4789 0.06 10 -0.4205 1.5309 2.0053 4.291 I 3.907 1
9.5372 10.6840 11.0130 11.2612 10.098 1 10.3526 9.3613 10.3292 12.1746 12.458I 9.8901 11.1359 8.5946 1 1.5723 10.1749 1 1.3673 9.1847 9.3921 10.8688
6.1521 6.4962 7.9714 8.4363 8.1560 8.8791 4.7785 6.3718 8.3223 7.9197 6.7534 8.2181 6.6289 5.8939 8.5835 9.5287 8.6139 9.1754 9.8153
173.10 - 178.36 - 179.72 170.29 163.75 154.95 171.96 - 166.11 - 174.41 166.24 162.00 148.29 175.86 179.41 -177.19 170.75 166.54 152.12 156.54
c-2 c-3 c-4 c-5 C-6 0-I 0-2 0-3 0-4 0-5 0-6 H- I H-2 H-3 H-4 H-5 H-6 I H-62
This Page Intentionally Left Blank
ADVANCES IN CARBOHYDRATE CHEMISTRY AND BIOCHEMISTRY. VOL. 52
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION, AND LOSSES IN SUGAR MANUFACTURE AND REFINING
BY MARGARET A. CLARKE," LESLIE A. EDYE,*AND GILLIANEGGLESTON~ *Sugar Processing Research Institute, lnc.,New Orleans, Louisiana 70124, USA, and TSRRC-ARSUSDA, New Orleans,Louisiana 70179, USA
.... ............ 441 ................................................... 444 111. Alkaline Degradation of Monosaccharides . . IV. Acid Hydrolysis of Sucrose ........................................................ 455 V. Acid Degradation of Monosaccharides ......... ....................... I. Introduction
11. Alkaline Degradation of Sucrose
VI. Effects of Degradation Reactions on Suc 1. Inversion Rates and Sucrose Loss ................................................ 2. The Control and Measurement of pH VII. Glossary of Sugar Industry Terms ...... ....................... References .................................
460
I. INTRODUCTION
The purpose of this account is to relate the current understanding of the mechanisms of sucrose degradation in aqueous acid and alkaline solutions to product loss in sugar manufacture and refining. Literature on thermal decomposition and color formation in aqueous sucrose solutions was summarized' in Sugar Technology Reviews by Kelly and Brown in 1978 and 1979. They covered topics such as acid- and base-catalyzed decomposition of sucrose and hexoses, and included work contained in 189 references dating from 1932 to 1974. This chapter does not repeat such a feat and the reader is referred to Kelly and Brown's review for a thorough historical perspective. The earlier work of Mauch' on the chemical properties of sucrose, an exhaustive review containing 212 references, is also worthy of note. The present account concentrates on work reported subsequent to the period covered by the review of Kelly and Brown.' Since 1974, much has been accomplished-especially in the elucidation of the mechanism of alkaline degradation of sucrose and hexoses. Some commonly held misconceptions on the subject of alkaline degradation of sucrose are later covered in detail. Outlines of the typical unit processes for the manufacture of sugar from sugar beet and sugar cane are illustrated in Figs. 1 and 2, and a glossary of trade and 0096-5332/97 $25.00
441
Copyright D 1997 by Academic Press. All rights of reproduction in any form reserved.
442
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
FIG.1.-Typical process flowchart for beet sugar production. Note: Variations occur from company to company; extensive recycling is not shown.
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
443
FIG.2.-Typical process flowchart for (A) production of raw sugar at a cane factory (or mill), and (B) production of white cane sugar at the cane refinery. Note: Variations occur from company to company; extensive recycling is not shown.
444
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
industry terms is appended in section VII. Sugar beets are grown in temperate climates in the northern hemisphere and are processed directly into white sugar at factories near the beet fields. In contrast, sugar cane requires a semi-tropical or tropical climate for growth, and is generally processed first into raw sugar at factories near the cane fields. Raw sugar takes the form of golden yellow/brown crystals, which contain approximately 97 to 98% sucrose, 0.5 to 1.0% moisture, 0.5% invert, and smaller amounts of “non-sugars,” such as inorganics and colored compounds. Raw sugar is subsequently transported to refineries, situated near the markets, where white sugar is produced. Some tropical countries’ cane factories produce a form of white sugar directly from sugar cane by a bleaching process (namely, sulfitation). This product, of lower quality than refined white sugar, is called plantation white, mill white, or direct white. One of the most profound differences between beet- and cane-sugar processes is that in white sugar manufacture, the colored, non-sugar compounds are more easily removed in the beet process. OF SUCROSE 11. ALKALINE DEGRADATION
It is a common (albeit erroneous) belief that the alkaline decomposition of sucrose proceeds initially via cleavage of the glycosidic linkage, resulting in either D-glucose and D-fructose or ionic forms of these monosaccharides. This is, in part, because of early assertions that “there is no doubt whatsoever that the influence of alkalis on sucrose consists of a splitting into D-glucose and D-fructose as the first reaction step”* and “alkaline degradation of sucrose to reducing sugars is probably the first step”’ (in the latter case, the authors refer to the 1958 review of Whistler and BeMillefl on alkaline degradation of polysaccharides, which, in fact, does not support such a mechanism). Although these claims were, at the time, intuitive, rather than based on empirical evidence, they have been perpetuThe issue has been further ated by repeated citationeR 5 - 8 and corroborati~n.~.’~ confused by the fact” that sucrose can hydrolyze to D-glucose and D-fructose by an acid-catalyzed mechanism in slightly alkaline solutions, up to pH 8.3. In 1970, Parker” reported that neither D-glucose nor D-fructose are formed, even transiently, during the hydroxyl-ion catalyzed decomposition of sucrose, his evidence being that hexitol was not detected in the presence of borohydride, and that the reducing properties of the solution toward femcyanide, in the presence of the cyanide ion, were not enhanced. Parker and othersI2 favored a mechanism wherein an internal nucleophilic displacement at the glycosidic linkage of a sucrose anion resulted initially in ionic forms of the monosaccharides, which rapidly formed acids of lower molecular weight. The review of Kelly and Brown’ refers to the work of Parker1’ and notes the “difference of opinion” on the mechanism of base-catalyzed sucrose decomposition. Although there was some contention, Kelly and Brown favored an inversion or hydrolysis mechanism. None of these mechanisms, however, offer a clear explanation for the alkaline lability of sucrose, as compared to related alkyl glycosides. 2
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
445
TABLEI Rate of Degradation of Sucrose and Model Compoundszo
Compound Sucrose Methyl P-D-fructosfuranoside (1) Methyl a-D-glucopyranoside (4) Octa-O-methylsucrose (7) Methyl a-D-fructofuranoside (2) Methyl 3,4-di-O-rnethyl-a-o-fructofuranoside (3)
lo4 X Initial Rate' (mol L-' h-') 19 CO. 1 CO. I CO. 1
20 CO. I
6.0 m M in 1 M NaOH at 100°C
In contrast to reducing sugars, sucrose and related alkyl glycosides are considerably more stable in alkali, and elucidation of the mechanism of reaction of the glycosides provides valuable insights into the sucrose mechanism. Several invest i g a t o r ~ ' ~ -have ' ~ examined the alkaline degradation of glycosides. In glycosides, a trans relationship between the aglycon and the 2-hydroxyl group of an aldoside or the 3-hydroxyl group of a ketoside allows a much more facile alkaline degradation than is the case for the cis analog. Accordingly, a-D-fructofuranosides degrade faster than P-D-fructofuranosides (as in the fructose moiety in the sucrose molecule) and P-D-ghcopyranosides degrade faster than a-D-glucopyranosides (as in the glucose moiety in the sucrose molecule) [compare methyl P-D-fructofuranoside (1) and methyl a-D-fructofuranoside (2) in Table I]. An internal nucleophilic substitution via the conjugate base (S,iCB mechanism) has been proposed" to account for this effect and involves an internal attack at the anomeric carbon by a trans-oxyanion (ionized hydroxyl group), resulting in an epoxide intermediate that rapidly hydrolyzes and further degrades (see Fig. 3). Furthermore, the involvement of an oxyanion a to the anomeric carbon is supported by the relative alkali stability of some 0-substituted glycosides [such as methyl 3,4-di-O-methyl-a-~-fructofuranoside (3), see Table I].
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
446
+ H20
Ho\
@
I
r.d.8.
HO
Degradation Products FIG.3.-The
mechanism of alkaline degradation of P-D-glucopyranosides.
In the case of sucrose, the ring C-OH groups adjacent to the anomeric carbon atoms on the glucose and fructose moieties are both cis to the glycosidic bonds. Thus, sucrose should be a relatively alkali-stable glycoside. Surprisingly then, by comparison with related alkyl glycosides [such as methyl a-D-glucopyranoside (4) and methyl P-D-fructofuranoside(2)], sucrose is relatively labile to alkaline degradation (see Table I). A full explanation for this has been given in a series of article^^^-^^ by Richards et al. and a novel hypothesis has been proposed. In a studyz3of the alkaline degradation of a mixture of mono-0-methylsucroses, some of the monomethyl derivatives were shown to degrade at a rate
447
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
similar to sucrose, but 1’45) and 3’-0-methylsucrose (6) were degraded much more slowly (primed numbers refer to the D-fructose moiety, as in the numbering system of Hockett and ZiefZ5).Earlier work20 by the same authors had indicated that the mechanism involved the oxyanions of free hydroxyl groups. Based on the observed alkali stability of octa-0-methylsucrose (7) and several partially methylated sucroses, it appeared unlikely that the mechanism involved direct attack by hydroxyl ion on the glycosidic bonds. Because only the 1’-(5) and 3 ’-0-methylsucroses ( 6 ) survived alkaline conditions that would completely degrade sucrose, it was concluded that the oxyanions from 1’-OH and 3’-OH were necessary for the alkaline degradation of sucrose. Simple displacement of the glycosidic linkage by the C-1’ or C-3’ oxyanion to form a glucose anion and a 1,2- or 2,3-fructose epoxide could be disregarded in view of the alkali stability of methyl P-D-fructofuranoside (1) and methyl 3,4-O-dimethyl-a-~-fructofuranoside (3) [methyl a-D-fructofuranoside (2) is alkali-labile (see Table I) and would react via the S,iCB mechanism already described].
OR8 OR6
Sucrose
H
H
H
H
H
H
H
H
1’-0-Methylsucrose
(5)
H
H
H
H
CH3
H
H
H
3’-0-Methylsucrose
(6)
H
H
H
H
H
CH3
H
H
Octa-Omethylsucrose
(7) CH3
CH3
CH3
CH3
CH3
CH3
CH3
CH3
Richards et al.23-24 proposed that the alkaline degradation reaction proceeds via a slow, rate-determining S,iCB mechanism, where the substitution at the C-1 of the D-glucose moiety by oxyanions derived from 1’-OH or 3’-OH resulted in 1- or 30-P-D-glucopyranosyl-D-fructose (see Fig. 4); the mechanism implies that 1’-0methylsucrose is degraded via 3’-displacement and 3’-O-methylsucrose via the 1’displacement. The 1- or 3-0-~-~-glucopyranosyl-~-fructose intermediates are then
448 M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
449
rapidly degraded by mechanisms, and at rates comparable to those of other reducing sugars. A major feature of this mechanism is that the alkali-catalyzed degradation of sucrose does not initially proceed via hydrolysis of the glycosidic linkage and the formation of D-glucose and D-fructose, or their ionic forms. Considering that the studies accomplished by Richards et a1.20-24were undertaken using chromatographic [liquid chromatography (HPLC) and gas- liquid chromatography (GC)] techniques, which are more sensitive than the cuprimetric, polarimetric, paper, and column partition-chromatographic techniques used by Parker'l and other ~ o r k e r s ? ~the . ~mechanism of Richards et uL20-" is more likely to be viable. Further studies with deoxysucroses (the syntheses of several deoxysucroses have been reported subsequent to the study of Richards et al.) as models, rather than methoxy derivatives (to eliminate steric effects), and using nuclear magnetic resonance (NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) to permit detailed investigation of the initial products from the alkaline degradation of sucrose, could verify this mechanism. Sucrose can, however, degrade to D-glucose and D-fructose in slightly alkaline solution at pH up to -8.3 (sucrose is most stable6*"at pH 8.3-8.5, although the reason for this requires some elucidation), but this degradation proceeds by the normal acid-hydrolysis mechanism. In sucrose manufacture, therefore, the main reaction causing sucrose loss, between pH 7 and about 8.3, is the same acid hydrolysis that occurs at lower (acid) pH. 111. ALKALINE DEGRADATION OF MONOSACCHARIDES
D-Glucose and D-fructose (invert sugars) are present in both cane and beet juice, and decompose on the addition of lime at high temperatures during purification of the juice. During juice purification and concentration, it is necessary to keep concentrations of invert sugar low. In addition to direct sucrose loss to invert sugar, undesirable dark-colored products can form in the juice via the Maillard reaction of amino acids and reducing sugars. In general, beet juice contains less invert sugar, but more nitrogen-containing compounds, than cane juice. Although deliberate and complete decomposition of invert sugar during juice purification is desirable in beet sugar manufacture, invert sugar decomposition is less critical to good process control in the cane sugar mill, where the lower concentration of primary amines makes the formation of Maillard reaction products less likely. In fact, it is considered an advantage, in cane sugar manufacture, to maintain a small concentration of invert sugar throughout the process because invert sugar, which remains in the mother liquor during crystallization, has a net effect of lowering sucrose levels in final molasses. Therefore, although alkaline degradation of sucrose does not initially proceed via monosaccharide intermediates, alkaline transformations of monosaccharides are still of importance in sucrose manufacture. The dissertationz6 by de Bruijn, "Monosaccharides in alkaline medium: isomerization, degradation and oligomerization" and other publications by
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
450
MONOSACCHARIDE
11
ionization, mutarotation
MONOSACCHARIDE ANION
11 1
enolization, isomerization
ENEDIOL ANION “degradation
CARBOXYLIC ACIDS FIG.5 . -Simplified overall reaction scheme of monosaccharides in alkaline medium.
de Bruijn et al.,27-30in our opinion represent well the state of knowledge on the complex network of reactions of reducing sugars in aqueous alkaline solution. This network involves both reversible and irreversible reactions (see Fig. 5). The reversible reactions are initiated by an equilibrium between neutral and ionized forms of the monosaccharides (see Fig. 6). The oxyanion at the anomenc carbon weakens the ring C - 0 bond and allows mutarotation and isomerization via an acyclic enediol intermediate. This reaction is responsible for the sometimes reported occurrence of D-mannose in alkaline mixtures of sucrose and invert sugar; the three reducing sugars are in equilibrium via the enediol intermediate. The mechanism of isomerization, known as the Lobry de Bruyn-
--OH
Enedio1
Aldose FIG.6.-Mutarotation
and isomerization of reducing sugars.
Ketose
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
45 1
Alberda van Eken.stein rearrangement, generates the enediol anion intermediate that might undergo nonreversible degradation reactions. The first step in the nonreversible degradation reactions is the formation of a reactive a-dicarbonyl species through the p-elimination of a hydroxide ion. The subsequent reaction pathways to all degradation products can be described by just five reaction types, namely, p-elimination, benzilic acid rearrangement, a dicarbonyl cleavage, aldol condensation, and retro-aldol condensation (see Fig. 7).3' Retro-aldol condensation and a-dicarbonyl cleavage involve C-C bond
(Z) &elimination H = O
5e 5 1
-H
R
A
(ZZ) benzilic acid rearrangement H R
R'
(ZZZ) wdicarbonyl clevage
= o e
H +
FIG.7.-The
R ' L O
mechanisms of alkaline degradation of monosaccharides.
452
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
Fie. 8.-General
scheme for alkaline degradation of monosaccharides.
scission and result in products of lower molecular weight. Benzilic acid rearrangement essentially involves the addition of a hydroxide ion, p-elimination, and the abstraction of a hydroxide ion. In the aldol condensation reaction, an adicarbonyl compound reacts with another carbonyl species to form an a,p-dihydroxy ketone or an aldehyde with consequent C-C bond formation, increasing the length of the carbon chain. A somewhat simplified reaction scheme is shown32in Fig. 8 with roman numerals indicating the reaction types shown in Fig. 7.
453
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION coon
t4c -0
I
won
c -0
I ' c=o
I
c=o
coon I cn
t
I * c=o I c=o I ncon
nc 3 0 I
:"a
K1.U
I
rrc,on 3.4-dylyurmybuIyrk ccld
%on coon
z-mtwnotrau ocld
amk a l d
rwn
,Lon I
c n p
I
ncon I
CHaon OlYCerlC ccld
coon
De Bruijn et al.26-30used chromatographic and spectroscopic techniques to analyze the effect of reaction variables (such as pH and monosaccharide concentration) on the product profile and developed a reaction model (see Fig. 9) that emphasized the role of a-dicarbonyl compounds. Some of the features of the model shown in Fig. 9 are:
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
454
< C6 a-dicarbonyls
4 c 6 acids
Isornerization via enediol anion Retro-aldolization(especially ketoses) Aldolization Enolization and p-elimination; 4a. to C, a-dicarbonyls 4b. to pyruvaldehyde 5. Benzilic acid rearrangement 6. a-Dicarbonyl cleavage to an acid and an aldehyde 7. (Retro-) aldolization of (di) carbonyls
1. 2. 3. 4.
FIG.9. -Reaction
model for alkaline degradation of reducing sugars.
High OH concentrations and the presence of Ca2+,rather than monovalent cations, favor route 2 over 4a (that is, lactic acid formation is favored by high pH), In the formation of I C , acids (namely, organic acids containing 6 or fewer carbon atoms), at OH- concentrations greater than 10 mM, route 5 occurs preferentially to route 6, and lactic acid and saccharinic acids predominate in the product, The precursors for >C, acids (namely, >C, a-dicarbonyls) are assumed to form by aldol condensation of a-dicarbonyl compounds with other carbonyl compounds (route 7), and termination of this oligomerization is
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
455
via route 5 to a >C, acid, or route 6 to an aldehyde (a >C, acid or a SC, acid depending on the size of the a-dicarbonyl), Moderate OH- concentrations (1 to 10 mM) and high monosaccharide (4) concentrations ( > l o mM) form >C, acids in yields up to 50% (based on monosaccharide). Some >C, acids have molecular weights equivalent to 2 to 4 monosaccharide units. There appeared to be a direct relationship between color formation and >C, acid formation. The reaction pathways to >C, acids provide an explanation for a phenomenon often observed in sugar refineries during carbonatation (purification) and concentration, that is, the disappearance of invert sugar with concurrent appearance of ~ o l o r .The ~ ~ temporarily .~~ high pH (up to pH 10.5) in refinery carbonatation initiates the formation of higher molecular-weight acids via cross-aldol condensation of a-dicarbonyl specie^,^^.^^ and further degradation can proceed during subsequent filtration and concentration. Iv. ACIDHYDROLYSIS OF SUCROSE The investigation of the reaction of sucrose in aqueous acid solution has a long history; it was the subject of several kinetic studies in the early 19th ~ e n t u r y , ~ and ~ - ~A' r r h e n i u ~developed ~~ the equation describing the effect of temperature on reaction rate using data from sucrose hydrolysis experiments. At the time of the review of Kelly and Brown,' it was generally accepted that the mechanism of acid-catalyzed hydrolysis of sucrose involved protonation of the glycosidic oxygen atom followed by heterolysis of the glycosidic bond to form the two monosaccharides, with one monosaccharide in the form of a cyclic oxocarbonium ion (see Fig. 10). Other mechanisms, for example, via protonation of a ring oxygen atom,39had been proposed, but held little favor. Richards4' favored fructosyl- oxygen bond-cleavage and used this mechanism to explain the increase in rate of sucrose inversion in the presence of divalent cations (see section VI.1). However, the site of bond cleavage remained to be confirmed, until in 1988 Mega and Van Etten4' reported the use of "0 shift in I3C nuclear magnetic resonance (NMR) to elucidate the point of bond cleavage in the acid-catalyzed hydrolysis of sucrose. Sucrose was hydrolyzed in the presence of H,I80, and the incorporation of "0 into the products was determined. The results clearly indicated fructosyl-oxygen bond cleavage. Thus, acid-catalyzed hydrolysis of sucrose initially yields D-glucose and a fructose oxocarbonium ion, which can react with water to form D-fructose and regenerate the H+ catalyst. As a consequence, further acid degradation of sucrose can be described by the action of acids on D-glucose and D-fructose.
G?@
Ho
x ?
r ?
P
FIG. lO.--The mechanism of acid hydrolysis of sucrose.
. ..
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
451
4 7
7
-H
-H R
R FIG.I I.-Enolization
of reducing sugars in acid solution.
V. ACIDDEGRADATION OF MONOSACCHARIDES The acid-catalyzed reactions of reducing sugars are complex, and in many ways, at least initially, similar to the reactions in alkali, but generally slower!* Under mild acid conditions (namely, pH 5-6 at O-6O0C), reducing sugars ionize and mutarotate; at lower pH (down to pH 3 or 4) and at higher temperatures (up to lOO"C), enolization and isomerization occurs. In alkaline solution, enolization is initiated by base attack and abstraction of a proton (Y to the carbonyl group (see Fig. 6). In an acid solution, enolization is initiated by direct protonation of the carbonyl group (see Fig. 11). Acids are in fact far less effective enolization catalysts than bases. As a consequence D-glucose and D-fructose in aqueous solution s h o ~maximum ~ ~ - stability ~ ~ between pH 3 and 4. It is clearly indicated in Kelly and Brown's review' that, under conditions described previously, the further acid-catalyzed reactions of reducing sugars [such as dehydration to 5-(hydroxymethyl)-2-furaldehyde (HMF)] are extremely slow. For example>5 although hydrolysis of sucrose (2.0 M) at pH 5.6 and 100°C was measurable in a few hours, the further decomposition of the invert sugar was demonstrated in a time scale of over 200 hours. Similarly, an 80% (w/w) solution of D-fructose, after refluxing for 16 hours at pH 6.9, yielded only 0.1% D-glucose and 0.6% HMF, calculated on the basis of the original D-fructose; however, the authors46 did not specify the amount of D-fructose that survived, which puts the relevance of the data in question. In contrast, a good yield of HMF (20% of theoretical) is obtained from D-fructose solution in greater than 0.25 M HCI (pH -0) at 95°C in a few hours:' At much higher temperatures (such as 390°C) and under pressure, in acid of lower concentration, high yields of HMF form from sucrose and D-fructose within seconds.48Unfortunately, these studies were conducted in quite pure sugar solutions, whereas in factory operations, the sugar solutions are relatively complex mixtures of sugars, along with other organic and inorganic compounds. Therefore, we question if these results can be extrapolated for application to industrial conditions. The mechanism of HMF formation from D-fructose and sucrose was reviewed by Antal et aL4*Several arguments were advanced for favoring a mechanism involving furanose rings and a fructose oxocarbonium ion over an open-chain p-elimination mechanism that proceeds via an enediol intermediate to a
-
458
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON TABLE Ir Reported Products of Fructose Decomposition in Water at Elevated temperature^^^
Dehydration
5-(Hydroxymethyl)-2-furaldehyde" 5-Methyl-2-furaldehydeh a-Angelica lactoneh P-Angelica lactoneb 2-(2-Hydroxyacetyl)furanh 2-(2-Hydroxyacetyl)furan formateh Isomaltol"
4-Hydrox y-2,3,5-hexanetrioneh 4-Hydroxy-2-(hydroxymethyl)-5methyl-3(2H)-furanoneh
Fragmentation formic acid" levulinic acid" dihydroxyacetone' glyceraldehyde' 2-furaldehyde" pyruvaldehyde" lactic acid" acetol" glycoaldehydeh acetic acid" 2,3-butandioneh
Condensation "humin"
Isomerization
D-glUCOSe"
Major products (generally >1% absolute yield) Minor products
3-deoxyhexulose (a mechanism similar to alkaline degradation). Several reviewe r ~ ~including ~ , ~ Kelly ~ , and ~ ~Brown' (who favored the latter scheme), discuss these alternative mechanisms. Here, it is sufficient to note that acid-catalyzed degradation of reducing sugars proceeds in complex reactions to products of isomerization, dehydration, fragmentation, and condensation. A typical product profile for decomposition of D-fructose is shown in Table 11. Note that with the possible exception of isomerization, none of the foregoing acid degradation reactions would be likely to occur to any large extent under conditions found in the sucrose-manufacturing industry. Under acid conditions in the manufacture of raw cane sugar, most reducing sugar degradation proceeds via MaiIlard reactions with amino acids, as outlined in Fig. 12."" These reactions contribute to sucrose loss and undesirable color formation. Although the reactions of amino acids with reducing sugars are important to the sucrose-manufacturing industry, they are beyond the scope of this chapter; instead, the reader is referred to more complete treatments of this s u b j e ~ t . ~ * , ~ ~ VI. EFFECTS OF DEGRADATION REACTIONS ON SUCROSE MANUFACTURE
The preceding sections of this chapter report on the current understanding of the mechanisms of sucrose degradation in aqueous acid and alkaline solution. Although our knowledge of these reactions has clearly advanced since 1974, the sucrose manufacturing and refining industry is essentially faced with the same problems of product loss. Unfortunately, the application of this knowledge to problem solving is complicated because many of the aforementioned studies
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
459
Sugar Carbonyl-Amine Reactions H
t
ti,
N-cn * co ,n HX
cn, co,n
maltol
I :N-C=C
Schlff Baa.. anollzmtlon.
cycllzmtlon. methyl rmarrmngammnt
-
OH
3-enmmlnol 'Reductond
no QIa I-hydrox~-6-methyl- 3-furmnone
FIG.12.-Carbonyl-amine
reactions leading to Maillard reaction products and reductones (adapted
from Ref. 51aL
were performed at pH values, temperatures, and sucrose concentrations outside the ranges typically encountered in the industrial situation. However, the following generalizations hold true: Sucrose degrades in acid far more easily than in alkali, and invert sugar (the product of acid hydrolysis) is far more reactive in alkali than in acid. In acid, the rate of hydrolysis of sucrose is faster than the rate of degra(2) dation of its inversion products. (3) In alkali, the rate of degradation of sucrose is much less than the rate of degradation of D-glucose or D-fructose. (1)
460
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
(4) Because alkali degradation of sucrose does not result in inversion products, in slightly alkaline solution (pH < -8.5), the loss of sucrose to invert sugar (glucose + fructose) is a consequence of the acid hydrolysis mechanism, which provides D-glucose and D-fructose for further alkaline degradation. Point 1 is especially relevant to sugar refineries, where pH at the first part of the process (where the raw sugar is dissolved and clarified) is often low enough to permit formation of invert sugar, whereas the pH later in the process (decolorization) is high enough to cause degradation of this invert sugar. Point 1 is also relevant to sugar beet factories (that is, where acid hydrolysis of sucrose during extraction is followed by alkaline degradation of invert sugar during juice purification). Point 2 relates to the sugar cane factory situation, where the pH remains below 7 for almost the entire process. Point 3 describes the pH range in the sugar beet factory after initial extraction of raw juice. In point 4, emphasis is placed on the danger of forming too much invert sugar during extraction in diffusion because subsequent decomposition of invert sugar causes high overall loss of sucrose and decreased recovery.
1. Inversion Rates and Sucrose Loss The literature over many years has tabulated rates for hydrolysis of sucrose and formation of invert (glucose fructose) at various concentrations, pHs and temperatures.”*”~ssThese studies, in general, were conducted in solutions of sucrose only, with pH adjusted by the addition of an acid or base, yielding solutions of very low ionic strength, inorganic content, or ash content. The muchquoted tables of King and Jisod4 result from the measurement of hydrolysis rates in 0.5 to 2.5% (w/v) solutions of sucrose; these tables are reproduced in both the Cane Sugar Handbooks4 and the Handbook of Sugars,56in the former case, with the unfortunate accompanying indication that the same rates could be applied in the 65- to 70-Brix (or % w/w) range. Part of the foundation for the aforementioned extrapolation of hydrolysis rate data from low sucrose concentration to refinery liquors at high sucrose concentrations is the assumption that impurities have no effect on reaction rate. Parker“ observed that increasing ionic strength up to 2 M as KC1 or 1 M as MgC1, increased the rate of sucrose hydrolysis, but he claimed that “the effect of salts on reaction rate was not sufficiently pronounced to be considered significant.” However, Parker neglected the “marginal influence of salt concentration” in developing an equation that related the first-order rate constant to pH, temperature, and the concentrations of water and of sucrose. In contrast, Clarke,s7in early studies on the use of HPLC to measure sucrose hydrolysis rates, observed hydrolysis rates greater than those previously reported in the l i t e r a t ~ r e , ” * when ~ ~ - ~reac~ tions were run at 0.1 M KCl (-0.7% KCl). After 6 hours, at pH 7, 9OoC, and
+
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
46 1
Sucrosc:Water:Sait(dlorides), 100’C
I
1
:
7
:.
0.05 moles
Time. hours FIG.13.-The effect of chloride salts on sucrose reaction rate.
60-Brix sucrose in water, 98.62% of the initial sucrose remained, whereas in 0.1 M KCl, 95.15% sucrose remained (an -3.5-fold increase in the hydrolysis rate at 0.1 M KCl). More recently, Richards:’ working in concentrated sucrose solutions (-70 Brix) at 100°C and -0.5% salt content, observed increases in rates of sucrose hydrolysis in the presence of salts. The addition of MgCl, affected a dramatic increase in hydrolysis rate, and addition of CaCl, and NaCl also affected the rate to lesser extents, as shown in Fig. 13. Richards proposed that the increase in the hydrolysis rate was caused by withdrawal of electrons from the glycosidic oxygen atom by protonation with the hydrated magnesium ion, as shown in Fig. 14. Sodium acetate, unlike sodium chloride, conferred stability on the sucrose. Richards interpreted this as being caused by the neutralization of secondary acidic-degradation products, which would form from any traces of primary hydrolysis products, by the weakly basic sodium acetate buffer. Furthermore,
/j‘ i
M g +( 0$1. FIG.14.-Catalysis
-
G1c\0/””
P” H
-
Glc
+ FlU0
FlU of glycosidic oxygen protonation by hydrated magnesium ions.
462
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
sodium acetate, where the cation is complexed with acetate, rather than hydrated, is not capable of protonating the sucrose glycosidic oxygen. Therefore, it would not, according to Richards' proposed mechanism, be expected to increase the rate of hydrolysis. The increased rate of hydrolysis in solutions having an ash (inorganics) content of 0.1- 1.0% reflects cane sugar refinery and raw sugar factory (sugar end) processing conditions more accurately than the rates in pure sucrose solutions of low concentration. Hydrolysis, or inversion, rates in refinery liquors and factory syrup^,^.^^ are more rapid than indicated in literature,' 's4-56 wherein ash levels in processing conditions were not simulated. Eggleston et have investigated the behavior of water structure-breaking and structure-enhancing solutes on the thermal degradation of sucrose in concentrated aqueous solutions (that is, simulated refinery liquors and factory syrups). The water structure-enhancers: ethanol, 2-methyl-2-propano1, and tetramethylammonium chloride, and the water structure-breakers: urea and guanidinium HCI, and salts (such as LiCl, NaCI, KCI, MgCl,, CaCl,, and AlC1,) were used to elucidate the role of water structure in the salt-catalyzed degradation of sucrose in concentrated aqueous solutions. Although non-ionic solutes that increase water structure suppressed sucrose degradation, the pH effects of ionic solutes were more significant than water structure-breaking effects. Initial results from a study of these reactions at constant pH, in both simulated and real refinery liquors and factory syrups, have been r e p ~ r t e d . ~ ~ ~ . ~ An important consequence of sucrose degradation is the development of color from degradation products. Kuridis and Mauch6' have developed an equation for the prediction of color development in model sucrose solutions. Color development was expressed as a function of temperature (90 to 120°C), time (0 to 80 rnin), pH (7.5 to 9.5), and composition of the solution (sucrose 20 to 60%, invert sugar 0.02 to 0.18%, and amino acids 1 to 3 gL). The authors claimed, with caution, that the effects of an intended alteration in a unit process in the refinery can be predicted in advance. Vukov6 has developed equations based on experimental data that predict the effect of temperature, pH, and ionic strength on rate constants of sucrose decomposition in acid and alkaline medium. Other workers6' report that Vukov's equation generally agrees with their experimental rate data. The literature on sucrose loss in manufacture is extensive, but not all studies have been conducted on the principles of sound scientific method. An example from the literature of a study with questionable results is a report by on the effect of pH on sucrose loss during boiling in the open-pan sulfitation (OPS) process. The OPS process is used in some tropical sugar cane growing areas to produce small amounts of a sugar product known as gur, panela, or piloncillo for local consumption. "Juice" (massecuite from Kenyan OPS mill diluted to 20 ~
1
.
~
~
3
~
~
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
463
Brix in a laboratory in the United Kingdom) was reclarified and re-evaporated by a method “comparable to that used in an OPS mill.” Sucrose :potassium (K) and invert sugar: K ratios were used to determine sucrose loss; in this way, data was corrected for volume changes. Reducing sugars and sucrose (by difference after acid hydrolysis) were determined by the Lane-Eynon method and potassium by atomic absorption spectroscopy (AAS). Cecil claimed that no measurable sucrose loss was detected between pH 6.5 and 7.5. Considering that oligoand polysaccharides interfere with the sugar analysis method and that some potassium salts must have been lost to the clarifier mud, the results could actually have shown a net gain of sucrose in the process. More direct quantitative methods [such as HPLC and ion chromatography (HPIC)] should have been used, although the application of such technology as AAS, HPLC, or HPIC to open-pan boiling is questionable in itself. At the other end of the technological spectrum is the use of statistical process control (SPC) by British Sugar in beet sugar factories to achieve better control of continuous plant operation^.^^ Until recently, SPC had mainly been used in batch processes with unit entities as products; measurement of a sample of product entities followed by statistical analysis indicated turning points in the process. The application of this method to a continuous product stream required a larger sample size to identify turning points that required corrective action. Parameters under control included cossette quality, pH between the first and second carbonatation, thick juice pH, waste condensate temperature, and standard liquor color (these factors affect sucrose hydrolysis and loss). This type of experiential control does not identify the cause of deviation from acceptable parameter values. The aim of SPC is to identify turning points, initiate corrective action, and reestablish control of the process. British Sugar reported great success with SPC in the last two sugar campaigns. A 1992 symposium64on refinery losses (measurement and control) revealed some of the difficulties in correlating literature reports of plant operations, and even more so with laboratory studies. A basic terminology problem exists with the use of the terms sucrose and pol to mean the same in some cases, and to mean different measurements in others. Considerable variation was found in the basics of loss reports, only one third of which (from the 29 companies that responded to the survey) actually called the report a loss statement. Loss was measured as a fraction of “melt (dissolved) solids” by only half of the survey respondents; others used “melt weight,” “melt pol,” or other denominators.@Furthermore, even the raw-sugar weight factor was not consistent; half of the respondents used settlement (purchase) scale, and half melt scale, with the difference between the two ranging from 0.1% to 1 .O% (figures that, perhaps not coincidentally, represent net or unknown sucrose loss in many refineries).@ In experimental studies, sucrose loss generally refers to chemical sucrose loss on
464
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
raw sugar solids input. In manufacturing, a point usefully emphasized by the symposium survey, chemical, physical, and accounting losses are all comb i r ~ e d Two . ~ ~ refineries could show identical “loss” figures; one could be real losses on packaging overweights and/or chemical loss, the other could be a “paper” loss from incorrect melt weights and product weights. The variety of materials weighed at different plants makes consistent mass-balance calculations almost impossible-even more so in factories than in refineries, although in many countries, factories within a given area do use consistent reporting practice. A useful summary of sucrose losses under good conditions was presented in the symposium by Latham,65as follows, for percent on melt solids: Loss in carbonatation with filtration: <0.01% Loss in phosphatation (scum loss): 0.01 -0.02% Loss on bone char (wash and burn): 0.07% Loss on carbon (equivalent decolorization use to bone char): 0.08% Loss on ion-exchange resin (equivalent decolorization use to bone char): 0.03% Loss in condenser water: <0.01% Loss in packaging (overweights): 0.09% The symposium was especially useful in pointing out the multitude of factors that can lead to, or be included in, “sugar loss.”
2. The Control and Measurement of pH In sugar refinery control operations, pH electrodes should not be, as unfortunately they sometimes are, calibrated with standard buffer solutions, then placed on stream in sugar liquors, and assumed to read equivalent pH. Implicit in this operation is the equivalence of pH electrode response in dilute aqueous buffers at -24°C and in high Brix sugar solutions at elevated temperatures. Such equivalence does not exist. Even in the case of laboratory research with dilute sucrose solutions, the measurement of pH at high temperatures is affected not only by the change in water activity (Kw=lO-I4 at 24” and 5.13 X lo-” at 100°C or pKw,,,=12.29 at 100°C66),but also by a change in the characteristics of the electrode used in the measurement. In investigations where a pH electrode is calibrated at 25” and pH measurements are made at much higher temperatures, the differences between calibration and operation temperatures certainly results in some error in the pH value. Furthermore, although many pH electrodes might produce stable pH readings, even in boiling alkaline solutions, the relationship between these observed pH values and the actual hydrogen-ion activities are often undetermined. The measurement of pH is further complicated by the effect of high concentrations of sucrose (such as 60 Brix or 60%w/w) on hydrogen ion activity.
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
465
Clarke67has written about the effect of sucrose solution structure on pH and calcium ion electrode processes and has shown a decreased response of these electrodes to changes in ionic activity in sucrose solutions at 60 Brix and 24°C. This decreased electrode response can, in part, be explained by the structural order of the sucrose- water mixture (molecular association in sucrose- water systems has been reviewed by Allen et In a 60-Brix sucrose solution, the ratio of water molecules to sucrose molecules is 12.7 : 1, with water molecules hydrogenbonded to sucrose (that is, in the solvation shell) in dynamic equilibrium with free water. Therefore, the concentration of free water molecules and dissociated ions is much less than in dilute sucrose solutions. The number of water molecules in the sucrose solvation shell depends on the extent of intramolecular hydrogen-bonding in the sucrose molecule. The effect of sucrose concentration and temperature on intramolecular hydrogen bonding in aqueous sucrose solutions is still not completely resolved, although advance^^^.^^ in molecular modeling suggest that the sucrose molecule has far more freedom of rotation about the glycosidic linkage (that is to say, less intramolecular hydrogen bonding) than previously Therefore, in most cases, pH values measured at high temperatures in dilute solution should be considered approximate values only. In cases where the investigators address this problem and are careful to select a suitable electrode (namely, one that manufacturers claim to have almost hysteresis-free pH measurement and a stable isopotential point over the temperature range), the error associated with electrode performance will be small, and differences in reported pH values will correspond to differences in actual pH. In cases where pH is measured in concentrated sucrose solutions, the reported pH value should be considered as a nominal value only, and the differences in nominal pH values might not correspond to actual differences in hydrogen ion activity. In process control, the change in pH is monitored to show gain or loss across a unit process, and to show trends. Regular recalibration of pH electrodes is essential for good control operation. Van der Poel et al.,72in 1982, described progress in development of computer and on-line control in CSM Suiker B. V. (CSM) beet sugar factories. Control methods in all aspects of factory operation were described; for the purpose of this chapter, control of pH during juice purification is covered. In addition to high-temperature glass electrodes inserted in the process stream, CSM installed electrodes in a thermostated bypass to measure pH at a lower temperature. CSM recognized that readings taken from these electrodes were nominal pH values only. Short-term decisions to adjust alkali concentrations with soda ash (Na+ZO,) or NaOH were based on the electrode response in a control loop with pH-value set points. The set points were regularly adjusted by using laboratory acid-base titration results, so problems with calibration of the electrodes were avoided.
466
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
Based on the aforementioned inadequacy of pH measurements, a cautious approach in the interpretation of fundamental research data in the industrial environment is warranted. For example, it would be unwise to conclude that a nominal pH value (from a pH electrode in a sugar refinery) greater than 8.5 indicates hydrogenion activities that are too low to catalyze sucrose hydrolysis at a significant rate. The net gain (perhaps even the lack of a net loss) of invert sugar across a unit process is the best indicator of acid hydrolysis. The use of pH electrodes in the sugar industry should be based on experiential evidence that maintaining the nominal pH above a minimum value does prevent sucrose loss to invert sugar. OF SUGAR INDUSTRY TERMS VII. GLOSSARY
BAGASSE The fibrous byproduct of sugar cane milling. BEET JUICE The soluble solids (and some fine particulates in suspension) extracted from beet cossettes (slices) by a countercurrent hot water (neutral or slightly alkaline pH) diffusion process. A small amount of soluble solids remains in the spent cossettes (or pulp). BONE! CHAR A decolorizing and de-ashing filtration material made from dried cattle bones that have been crushed and retorted (at >550°C) to activate their alkaline calcium phosphate crystalline structure and carbonaceous residue. BRIX The percentage by weight of the solids in a sucrose solution. CANE JUICE The soluble solids (and some fine particulates in suspension) extracted from chopped cane by crushing (milling) or diffusion in a countercurrent hot water (neutral or slightly acidic pH) process. A small amount of soluble solids remains in the spent crushed cane (bagasse). CARBONATATION The process of purifying juice by adding an excess of calcium hydroxide (lime) at -75OC and removing the surplus by precipitation with carbon dioxide and filtering the resulting calcium carbonate. CLARILlER Equipment primarily used to remove suspended solids and/or colloidal materials from a liquid. As applied to sugar, these are normally either flotation (refinery) or sedimentation (factory) devices. See PHOSPHATATION. COSSETTES Slender strips of beets, ideally with a “V” cross-sectional shape, cut by slicing machinery prior to extraction of sucrose by diffusion. EVAPORATION The removal of water from sugar liquor as its vapor. In sugar processing this is normally done under a controlled vacuum. FACTORY SYRUP The concentrated juice from the evaporators, before crystallization has occurred. INVERT (SUGAR) The product of the hydrolysis of sucrose: an equal mixture of D-glucose and D-fructose. MASSECUITE A mechanical mixture of crystals in mother liquor (molasses or heavy syrup), produced in a vacuum pan. The suspension of sugar crystals in mother liquor produced during the early stages of crystallization.
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
461
MELT Raw sugar-refining terminology, meaning dissolve. A refinery’s melt is a measure of the total intake of raw sugar. MELT WEIGHT The weight of the dissolved constituents. MELT SOLIDS The measure of the total dissolved solids. OPEN PAN SULFITATION (OPS) A sugar cane mill process wherein sugar solutions are concentrated by boiling in an open pan at atmospheric pressure, rather than under a vacuum, and bleached (see SULFITATION) to produce a white sugar product. PANNACUUM PAN Equipment used for controlled crystallization of sugar solutions by boiling under a vacuum. PHOSPHATATION A clarification process where phosphoric acid or a soluble phosphate is used with lime and heat. The impurities are removed by flocculation, flotation, and surface scraping. PLANTATION WHITE White sugar produced in a cane sugar factory by the sulfite bleaching of cane juice. POL The value determined by direct or single polarization of the “normal weight” of a sugar product or process stream in a polarimeter (saccharimeter). The “normal weight” (26 g in a 100-mL aqueous solution) of pure sucrose reads 100% or 100” pol in a polarimeter calibrated for sucrose measurement with a standard quartz plate. RAW SUGAR The product of sugar cane factories or mills. An intermediate, colored crystalline product resulting from the clarification and evaporation of water from sugar cane stalk juice. REFINERY LIQUOR A high-Brix, sugar-containing solution recovered at various stages of the refining process. SUGAR BEET FACTORY (or sugar cane factory) A sugar beet processing facility in which refined sugar is recovered from harvested sugar beets; (or, a facility in which harvested sugar cane is processed into raw sugar). SUGAR MILL The term applied to a sugar cane factory, where sugar cane stalks are converted into raw sugar, or to the equipment that mechanically crushes and pulverizes the sugar cane stalks prior to extraction of the sugarcontaining juices. SUGAR REFINERY A processing facility in which nonsugar impurities are removed from raw sugar to produce a variety of sugar products. SULFITATION A purification and bleaching process used in most sugar beet factories. Generally, a small amount of sulfur dioxide is added to the sugarbeet juice to lower the pH of the carbonatation mixture and minimize color formation during subsequent processing steps. Sulfitation is also used in sugar cane factories or mills (outside the United States) for the direct production of white sugar without refining. This white sugar, known as plantation white, direct white, or mill white, is for local consumption; raw sugar is shipped to refineries near to larger consumer markets.
468
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
REFERENCES F. H. C. Kelly and D. W. Brown, Sugar Technol. Rev., 6 (1978,1979) 1-48. W. Mauch, Sugar Technol. Rev. 1 (1971) 239-290. P. E. Shaw, J. H. Tatum, and R. E. Berry, .I. Agric. Food Chem., 17 (1969) 907. R. L. Whistler and J. N. BeMiller, Adv. Carhohydr. Chem., 13 (1958) 289-330. M. A. Clarke, E. J. Roberts, M. A. Godshall, M. A. Brannan, E G. Carpenter, and E. E. Coll, Sugary Azucar, 17(3) (1980) 64-68. 6. K. Vukov, Int. Sugar J . , 67 (1965) 172-175. 7. V. Maurandi and S. Murandi, La Sucrerie Belge. 96 (1977) 283-291. 8. L. I. Trebin, I. A. Oleinik, I. V. Dushchenko, and I. A. Plokhikh, Ref. Zhurn. AN SSSR (Khim.),
1. 2. 3. 4. 5.
10 (1991) 1011452. 9. A. Carruthers, J. F. T. Oldfield, M. Shore, and A. E. Wootton, Int. Sugar J . , 56 (1954) 218. 10. R. Weidenhagen, C. R. Commission Internationale Technique De Sucrerie (C.I.T.S.),(1957) 43 -54. 11. K. J. Parker, La Sucrerie Belge, 89 (1970) 119- 126. 12. R. Montgomery, Ind. Eng. Chem.,45 (1953) 1144- 1147. 13. W. G. Overend, in W. Pigman and D. Horton (Eds.), The Carbohydrates: Chemistry and Biochemisrry, pp. 279-353,2nd ed., Vol. 1A, Academic Press, New York, 1972. 14. B. Capon, Chem. Rev., 69 (1969) 429-433. 15. C. E. Ballou, Adv. Carhohydr. Chem., 9 (1954) 59-95. 16. E. Dryselius, B. Lindberg, and 0. Theander, Acta Chem. Scand., 12 (1958) 340-342. 17. Y. Z. Lai and D. E. Ontto, Carbohydr. Res.. 75 (1979) 51 -59. 18. R. C. Gasman and D. C. Johnson,J. Org. Chem., 31 (1966) 1830-1838. 19. C. M. McCloskey and G. H. Coleman, J . Org. Chem., 10 (1945) 184-193. 20. G. W. O’Donnell and G. N. Richards, Aust. J . Chem., 26 (1973) 2041-2049. 21. G. N. Richards, IXth International Symp. Carbohydr. Chem.,pp. 21 -22, London, UK, 1978. 22. M. Manley-Harris, W. Moody, and G. N. Richards, Aust. J . Chem., 33 (1980) 1041- 1047. 23. M. Manley-Harris and G. N. Richards, Carbohydr. Res., 90 (1981) 27-40. 24. W. Moody and G. N. Richards, Carbohydr. Res., 93 (1981) 83-90. 25. R. C. Hockett and M. Zief, J . Am. Chem. Soc.. 72 (1950) 1839. 26. J. M. de Bruijn, Monosaccharides in alkaline medium: isomerization, degradation and oligomerization., Ph.D. Thesis, Delft University of Technology, The Netherlands, 1986. 27. J. M. de Bmijn, A. P. G . Keiboom, H. van Bekkum, and P. W. van der Pod, Int. Sugar J., 86 (1984) 195-199. 28. J. M. de Bruijn, A. P. G. Keiboom, H. van Bekkum, and P. W. van der Poel, Sugar Technol. Rev., 13 (1986) 21-52. 29. J. M. de Bruijn, A. P. G. Keiboom, and H. van Bekkum, Reel. Trav. Chim. Pays-Bas, 105 (1986) 176-183. 30. J. M. de Bruijn, P. W. van der Pod, A. P.G. Keiboom, and H. van Bekkum, Commission Internationale Technique De Sucrerie (C.I.T.S.),Ferrara, Italy, (1987) 1-25, 31. G . de Wit, Gedrag van glucose, fructose en verwante suikers in alkalisch milieu, Ph.D. Thesis, Delft University of Technology, The Netherlands, 1979; reference from de Bruijn.26 32. G. de Wit, Chem. Weekhl.,(1976) 139; reference from de Bruijn.26 33. M. A. Clarke, Invert Gain Symposium: Ways 10 improve refinery yield, Proc. Sugar Ind. Technol., 41 (1982) 149-159. 34. Symposium on Refinery Losses, Proc. Sugar Ind. Technol.. 51 (1992) 115- 150. 35. N. Clement and C. B. Desormes, Ann. Chim. Phys., 59 (1806) 329-339. 36. L. Wilhelmy,Ann. Phys. Chem. (Leipzig), 81 (1850) 413-433.
SUCROSE DECOMPOSITION IN AQUEOUS SOLUTION
469
F. Urech, Ber., 16 (1883) 762-766. S. Arrhenius, 2. Phys. Chem. (Leipig),4 (1889) 226-248. C. A. Bunton, T. A. Lewis, D. R. Llewellyn, and C. A. Vernon, J . Chem. SOC.,(1955) 4419. G . N. Richards, in M. A. Clarke, and M. A. Godshall (Eds.), Chemistry and Processing of Sugurbeet and Sugarcane. Sugar Series 9, Elsevier, Amsterdam, 1988, pp 253-264. 41. T.L. Mega and R. L. Van Etten, .I. Am. Chem. SOC..110 (1988) 6372-6376. 42. W. Pigman and E. F. L. J. Anet, in W. Pigman and D. Horton (Eds.), The Carbohydrates, 2nd ed., Vol. lA, pp. 165- 194, Academic Press, new York, 1972. 43. E. J. McDonald, J . Res. Nut. Bur. Stand., 45 (1950) 200. 44. J. A. Mathews and R. F. Jackson, Bur. Stand. J. Res., 11 (1933) 619. 45. S. E. Kharin and A. R. Sapronov, Inr. SugarJ., 71 (1969) 122. 46. M. L. Wolfrom and W. L. Shilling, J . Am. Chem. SOC..73 (1951) 3557. 47. B. F. M. Kuster and H. S. van der Baan, Carbohydr. Res., 54 (1977) 165-176. 48. B. F. M. Kuster and H. M. G. Temmink, Carbohydr. Res., 54 (1977) 185-191. 49. M. J. Antal, Jr., W. S. L. Mok, and G. N. Richards, Carbohydr. Res. 199 (1990) 91-109. 50. E. F. L. J.Anet,Adv. Carbohydr: Chem., 19 (1964) 181-218. 51. M. S. Feather and J. F. Harris, Adv. Carbohydr. Chem. Biochem., 28 (1973) 161-224. 51a. H. Paulsen and K. W. Pflughaupt, in W. Pigman and D. Horton (Eds.), The Carbohydrafes,2nd ed., Vol. IB, pp. 913-915, Academic Press, New York, 1983. 52. The Maillard Reaction in Foods and Nutrition, in G. R. Waller and M. S. Feather (Eds.), ACS Symposium Series 2 15,American Chemical Society, Washington D.C., 1983. 53. Maillard Reactions in Food; Chemical, Physiological and Technological Aspects, in C. Eriksson (Ed.), Progress in Food and Nutrition Science 5 , Pergamon Press, Oxford, 1981. 54. G. L. Spencer and G. P. Meade, in Cane Sugar Handbook, 9th ed., pp. 26-27, John Wiley & Sons, New York, 1963. 55. P. M. Win, Technology of Beet-sugar Production and Refining, Published for the U.S. Department of Agriculture and the National Science Foundation, Washington, DC by the Israel Program for Scientific Translations (1964). 56. H. M. Pancoast and W. R. Junk, in Handbook of Sugars, 2nd ed., AVI Publishing Co., Westport, CT, 1980. 57. M. A. Clarke, M. A. Brannan, and F. G. Carpenter, Proc. I976 Technical Session on Cane Sugar Refining Research, New Orleans, LA (Jan. 1977) 46-56. 58. G. Eggleston, J. R. Vercellotti, L. A. Edye, and M. A. Clarke, J . Carbohydr. Chem., 14 (1995) 1035- 1042. 59. G. Eggleston, J. R. Vercellotti, L. A. Edye, and M. A. Clarke, J . Carbohydr. Chem., 15 (1996) 81-94. 59a. G. Eggleston, Proc. 1996 Con$ Sugar Proc. Res., New Orleans (1996) 244-261. 59b. G. Eggleston, A. B. Pepperman and M. A. Clarke, Int’i Sugar J . (1996) in press. 60. S. Kurudis and W. Mauch, Zuckerind., 116 (1991) 261 -265. 61. J. M. de Bruijn, P. W. van der Poel, R. Heringa, and M. van den Bliek, Commission Znternationale Technique De Sucrerie (C.I.T.S.), Cambridge, U.K., (1991) 379-390. 62. J. E. Cecil, Trop. Sci.. 28 (1988) 133-139. 63. K. M. A. Sanigar, C. W. C. Harvey, and H. Morten, Zuckerind., 117 (1992) 94-98. 64. D. C. Webster, Symposium on Refinery Losses, Proc. Sugar Znd. Technol., 51 (1992) 73-84. 65. A. B. M. Latham, Symposium on Refinery Losses, Proc. Sugar Ind. Technol., 51 (1992) 115- 128. 66. W. L. Marshall and E. U. Frank. J . Chem. Phys. Ref. Data, 10 (1981) 295-304. 67. M. A. Clarke. Proc. I970 Technical Session on Cane Sugar Refining Research, Boston, MA (Oct., 1970) 179- 188.
37. 38. 39. 40.
M. A. CLARKE, L. A. EDYE, AND G. EGGLESTON
470
68. A. T. Allen, R. M. Wood, and M. P. McDonald, Sugar Tech. Rev., 2 (1974) 165- 180. 69. L. Poppe and H. van Halbeek, J . Am. Chem. Soc., 114 (1992) 1092- 1094. 70. S. Perez, C. Meyer, A. Imberty, and A. D. French, in M. Mathlouthi, J. A. Kanters and G. Birch (Eds.), Sweet Taste Chemoreception, pp. 55-73. Elsevier, Amsterdam, 1992. 71. K. Bock and R. A. Lemieux, Carbohydr. Res., 100 (1982) 63-74. 72. P. W. van der Pod, N. H. M. de Visser, and C. C. Bleyenberg, Sugar Technol. Reviews, 9 (1982)
1-58.
AUTHOR INDEX Numbers in parentheses are footnote reference numbers and indicate that an author’s work is referred to although the name is not cited in the text.
A
Aberg, P. M., 191,203(105) Akai, T., 215,220, 236(62) Albizati, K. F., 224,228,231, 237( 104). 2256 Allen, A. T., 465,470(68) Altona, C., 224,237(107) Amatore, C., 186, 187,202(85) Andersson, F. 0.. 181, 183, 185, 190, 198, 201(47,52),202(61), 202(93) Ando, K., 191,204(144-145) Ando,T., 191,203(126) Anet, E. F. L. J., 457,458,469(42,50) Angyal, S. J., 226,238(113), 248,249,296, 309(61) Antal, Jr., M. J., 458,469(49) Apparu, M., 181,201(46) Amott, S . , 318,319,322,323,348, 350, 353, 366,369,372,373, 374, 375,376, 377, 378,379,381,382-383, 386,395,396, 401(8-9, 11-12),402(31,40-55. 58,60), 403(96), 404( 107, 114) Arrhenius, S., 455,469(38) Ashraf Shalaby, M., 212,227, 235(26) Atalla, R. H., 330,403(69) Atkins, E. D. T., 322,323, 335,338,339,353, 358,361,370, 377,378,379, 381, 382, 383,386,395,401(23), 402(32-33,37,49, 52,54), 403(8 1-82, loo), 404(101, 103, 106, 112, 114) Atwool, P.T., 386,404(112) Augeri, D., 191, 199,204(143),205(187) Austin, R., 306,309(82) Auzanneau, I., 191,203(106-107) Azumi, C., 303,309(70,72-73)
B Backstr0m.A. D., 281,306,308(30), 309(82) Bacquet, C., 185,202(65) Baczynskeyj, L., 278,308(25)
47 1
Baek, Y. J., 234,238( 142) Balatoni, L.. 191,204(166) Ballou, C. E., 445,468(15) Banoub, J., 180, 184,201(15),20208) Barker, R., 295,296,299,303, 308(59-60) Batchelor, R. J., 191,204(149) Beck, R. H. F., 214,236(50) Begley. Jr., T. P., 281, 308(30) Behre, C., 2 10,232,235(6),242,244 Bellion, E., 276,307(15, 17) BeMiller, J. H., 444, 468(4) Benett, R. B., 278,308(28) Berglund, K. A., 212,233,235(20), 238(129) Berry, R. E., 444,449,468(3) Bethell, G. S., 296,309(61) Betzel, C., 33 1,344,403(90), 403(74) Beveridge, R. J., 296,309(61) Bezkorovainy, A., 234,238( 140) Bhatti, B. S., 191,204(162) Bigelow, S. S., 185,202(67) Bilodeau, M. T., 181,200,201(29) Biloski, A,, 322,346,402(29) Binkley, R. W., 212,213,233,235(27,30), 238( 127), 250 Binkley, W. W., 210, 21 1,212,213,221,233, 235(9- 10,27,30), 238( 127), 242,244, 250 Birberg, W., 191, 198,202(75), 203(108) Blackwell, J., 322, 326, 330, 332, 333, 401( 19-21), 403(77-78) Blair, M. G., 210,235(8), 242,244 Blanc-Muesser, M., 181,201(46) Blanco, J. L. J., 191,204(150) Blandshard, J. M. V., 340,342,403(89) Bleyenberg, C. C., 465,470(72) Blize, A. E., 222,230,231,232,237(95), 245, 249 Blomberg, L., 191,203(105) Bluhm, T. L., 322,345,347,402(30), 403(91,95) Bochkov, A. F., 180, 200(6)
472
AUTHOR INDEX
Bock, K., 220,225,228,229,237(84), 243,244. 246,249,250,251,465,470(71) Bodycote, E. W., 21 1,235(15), 242,244 Boggs, L. A., 212,219,235(23), 243 Bogusiak, J., 183,201(53) Bonvicino, G. E., 271,307(3) Boons, G. J., 191,202(95), 203(96, 110) Boons, G. J. P. H., 191.203(109), 205(174) Booth, H., 225,238(110) Booy, F. P., 345,403(92) Boudeulle, M., 332,403(76) Bouffar-Roupe, C., 370,404(105) Bourne, E. J., 8 Braccini, I., 189, 193,202(89) Bracht, A., 234,239( 146) Brannan, M. A., 444,460,462,468(5), 469(57) Bratton, A. C., 299,309(65) Brice, C., 181,201(39) Britten, J. F., 278, 281, 308(27) Brook, M. S., 305,309(77) Brown, D. S . , 199,205(188) Brown, D. W., 441,444,455,457,458,468(1) Buchanan, E. R., 285, 308(38) Buchrnan, E. R., 271,307(2) Buitenhuis. J., 212,226,228,235(29) BulCon, A., 322,340,342,402(26) Bundle, D. R., 191,203(104,106-107). 204( 158) Bunton, C. A,, 455,469(39) Biitner, G., 344,403(90)
Chandrasekaran, R., 313,320,322,323, 362,366,383,384,386,388,389,393, 401(7, 16), 402(39,41,54-57.61). 404( 1 10- 1 11, 113) Chanzy, H., 322,330,332,335,340,342,345, 402(26), 403(70-72,76,81,92) Chavan, J., 210,235(5), 242 Cheng,Y., 199,205(185) Chien,Y. Y., 323, 395,402(59) Chinzaka, T., 215,236(57) Chiu, A. K. B.. 239(148), 243,244,252 Choay, J., 383,404(109) Chu, N. J., 224,237(105) Chu,Y. D., 212,233,235(20), 238(128-129) Chuah, C. T., 322,361,402(35) Chung, B. Y., 180, 184,201(22) Clarke, M. A., 444,455,460,462,465, 468(4, 33), 469(57-59,59b, 67) Clement, N., 455,468(35) Cochran, W., 320,401 (1 8) Coleman, G. H., 445,468(19) Coll, E. E., 444,468(5) Contour, M. 0.. 181,201(32) Coste-Sarguet, A., 239(150), 260,261,262,263, 265 Cottier, L., 231,238(120-121) C0vey.T. R., 281,308(31) Craig, D. C., 226,238( 1 13). 248,249 Cremer, D., 72, 170(22), 226,238(114) Crick, F. H. C., 320,401(18) Cusack, N. J., 294, 308(55)
C
D
(?adov& E., 239( 149), 243,244,246,247,249, 252 Cad, J. J., 323, 378,381,402(51) Calvoflores, F. G., 191, 204(163) Cameron, T. S., 228,238(118) Cao, S., 183,201(52) Capek, K., 239(149), 243,244,246,247,249, 252 Capon, B., 445,468( 14) Carlstrorn, D., 322, 333.401(22) Carpenter, F. G., 444,460,462,468(5), 469(57) Carruthers, A., 444,468(9) Caw, B., 383,404( 109) Cecil, J. E., 462,469(62) Cerny, M., 183,201(50) Chan,T. H., 191,203(111)
Danishefsky, S. J., 181,200,201(29) Dasgupta, F., 181,201(33) David, S., 268,269,271,274,276,278,279, 291,293,295.296,297,299,303,307( 1, 4,9), 308(21-22,50,58), 309(64,67) de Bruijn, J. M., 449,450,453,455,462, 468(26- 30), 469(6 1) De Bruyne, C. K., 181,201(44) de Haan, P.G., 305,309(76) de Visser, N. H. M., 465,470(72) de Wit, G., 451,452,468(31-32) Dea, I. C. M., 322,323,366,369, 383, 402(41-42.53) Debzi, E. M., 330,403(72) Defaye, J., 181,201(32,46), 212,213,216,217, 218,219,220,221,222,223,225,226,
473
AUTHOR INDEX 228,229,230.231, 232,233,234, 23331). 237(76,80-82, 84-86, 88-89,94,99), 238(113, 119, 131),239(147, lSO-151), 243,244,245,246,247,248,249,250, 251,252,254,255,257,258,260,261, 262,263,264,265,266 Delhriick, K., 181,201(41) DeMoll, E., 276,307(18) Derouet, C., 189, 193,202(89) Descotes, G., 231,238( 120- 121) Deslandes,Y., 322,356,358. 361,402(35-36), 403(98) Deslongchamps, P., 225,228,232, 238(111, 124) Desormes, C. B., 455,468(35) Dewildt, J., 191, 205(183) Dezwart, M., 191,204(165) Diehl, D. R., 233, 238( 127) Dills, Jr., W. L.. 281, 308(31) Dolle, R. E., 180, 184, I98,20 l(24) Douce, R., 277,284,305,308(23), 309(80) Douwes, M., 191, 205(176) Driguez, H., 181,201(46) Dryselius, E., 445,468( 16) Dudley, R. L., 227,238(115) Dushchenko, I. V., 444,468(8)
E Earnshaw, A,, 216,237(74) Ebihara, M., 186,202(84) Edye, L. A,, 462,469(58-59) Eggleston, G., 462,469(58-59,59a, 59h) Egi, Y., 305,309(79) Eida, T., 233,238(137) Einstein, F. W. B., 191, 204(149) Ekelof, K., 198,205(184) Enornoto, K., 214,236(47-48) Esnault, J., 189, 193,202(89) Estramareix,B., 268,269.27 1,276,278,279. 284,293,294,295,296, 297,299, 303, 305,307(1,4-5, 13, 16). 308(20-22, 36-37,56,58), 309(63-64) Evans, W. L., 180, 200(2) Excoffier, G., 330,403(72)
F Faleschini, P., 362,404(102) Farnell, S., 322, 335,338,401(23)
Faust, J. R., 276,307(15) Feather, M. S., 458,469(51) Fei,C. P., 191,203(111) Fernandez, J. M. G., 191,204(150) Femer, R. 3.. 181,185,201(36-37). 202(62) Ferro, D. R., 383,404( 109) Filernon, W., 191,205(174) Fischer, E., 48, 170(16), 181,201(41) Fischer, J. C., 276,278,279,288, 308(20-22.45) Fontana, J. D., 234, 239(146) Foord, S. A., 370,404( 103) Forsberg, K. H., 232,233,238(125) Franczek, F. R., 212,227,235(26) Frank, E. U.,464,469(66) Franks, M., 299,309(66) Fraser-Reid, B., I8 I , 184, 186, 189, 201(26-27). 202(82,90) Frei, E., 334,335,337,403(79) French,A. D., 227,228,230,238(115-116), 465,470(70) French, D., 340, 342,403(88) Fuentes, J., 191,203(112), 204(150) Fuentes Mota, J., 239(150), 260,261,262,263, 265 Fuentes Mota, J., 191,203(113) Fiigedi, P., 183, 185, 186, 189, 190, 191, 198, 202(56,60-61.75.86). 203(116) Fujii, S., 215, 236(57) Fujita, M., 228, 238( 117) Fujita, S., 191, 203(114) Fukase,K., 191,203(115) Fukuzawa, Y.,322,356,402(34) Fulrner, A., 322,369,402(42) Fulton, W. S., 358,403(100) Furneaux, R., 181,201(36-37) Furuhata, K., 186,202(84) Furui, H., 191,204(144-145) Fushirni, K., 191,203(124)
G Gabhay, S. M., 338,339,403(83) Gadelle, A,, 212, 213, 217, 218, 219, 220, 221, 223.225,228,229,231,232,233,234, 235(31), 237(80,82,84), 238(113, 119, 13I), 239( l50), 243,244,246,247,248, 249,250,25 1,260,261,262,263,265,266 Gama,Y., 191,203(117) Garcia Fernlndez, J. M., 220,22 1,223,226,
474
AUTHOR INDEX
228,229,230,231,233,234,237(85-86, 88-89,94,99), 238(119, 131). 239(147, 150-151). 244,245,254,255,257,260, 261,262,263,264,265,266 Garcia Riuz, P. A., 222,237(91) Garciamendoza, P., 191,204(163) Gardiner, E. S., 326,403(64) Gardner, K. H., 322,326,330,333,377, 401(19,21), 404(106) Garegg,P. J., 180, 181,183, 185, 186, 189, 190, 191, 198,200(11),201(33), 202(56,60-61,69,75,77, 86-88,92), 203(116, 118) Gasman, R. C., 445,468( 18) Gatti, G., 383,404(109) Gaudy, D., 276,284,307(16), 308(36) Gessler. K., 331,403(74) Geurtsen, R., 191,202(95) Glaudemans, C. P. J., 191,204(160) Godshall, M. A., 444,468(5) Goergen, S. M., 211,232,235(12), 238(122), 242.244 Gonzalezeulate, E., 191,203(112) Grand-Maitre, C.. 181,201(47) Grant, G. T., 355,403(97) Green, C. P., 299,309(66) Greenwood, N. N., 216,237(74) Grenier, M. F., 23 1,238( 120) Grey,A. A., 212,213,235(27), 250 Grice,P., 191,203(110) Grue-Soerensen, G., 274, 307(10) Griinewald, H., 181,201(43) Guide to IUPAC Nomenclature of Organic Compounds, 47,53,56,81,91, 106,11 I , 113, 116, 129, 134, 144, 145, 170(14) GUrijah, V. R., 191, 204(151) Gurjar, M. K., 239(148), 243,244,252 Guss, J. M., 323,372,373,377,378, 383, 402(43,53), 404( 107)
H Hada, N., 191,203( 119) Haga, M., 183,201(51) Hallgren, C., 190, 191, 195, 198, 202(92), 203(99) Hamada, K.,221,237(90), 243,246,25 1 Hamalainen, L., 232,233,238( 125) Hamilton, W. C., 320,401(17) Hanessian, S., 184, 185,202(58,65)
Harada, T., 191.2051 177), 322,356(99), 356, 358,402(34) Haraguchi, K., 214,215,233,236(42-43, 65-66), 238(134) Haraldsson, M., 191,203(120) Harris, J. F., 458,469(51) Harvey, C. W. C., 463,469(63) Hasegawa, A., 191, 192, 193,203(97-98, 100, 121- 132), 2O4(136- 137, 144- 1 4 3 , 205( 172- 173, 178) Hashiguchi, S., 214,236(54) Hashimoto, H., 220,222,237(87), 254,257 Hashimoto, N., 215,236(60) Hasuoka, A., 191,203(115) Hattori, K., 228,238(117) Hauly, M. C. O., 234,239( 146) Haworth, W. N., 2.5.21 I , 232,235(14-15). 242,244 Hay, R. W., 185,202(62) Hayashi, J., 326,403(63) Hayashi, K.. 214,236(42-43) Hayashiji, M., 291,308(49) Hayes, M. L., 296,308(60) Helferich, B., 180. 181, 183,201(21,43) Helland, C. C., 189,202(88) Hemscheidt, T., 278,281, 308(27) Hendriks, K., 180, 183, 201(25) Hendrixson, T.L., 322,337,401(24) Hennessy, D. J., 271, 307(3) Heringa, R., 462,469(61) Hernandezmateo, F., 191,204(163) Hervd de Penhoat, C., 189,193,202(89) Hidaka, H., 233,234,238(137- 138) Hilditch, B. J., 294,308(55) Hill, R. E., 287, 308(39-40) Hilton, H. W., 208,210,211,212,218,221, 235(2,9- 10,22), 242.243.244 Hinrichs, W., 344,403190) Hirai, K., 222,237(92) Hirayama, M., 234,238(138) Hirayama. S., 214,236(47) Hiroaki, 0..221,237(90), 243,246,251 Hirschmann, R. F., 217,237(77) Hirshfeld, H., 271,274, 303,307(4,9), 309(67) Hirst, E. L., 5 Ho, W. M. L., 281,308(31) Hockett, R. C., 447,468(25) Hoeksema, H., 278,308(25) Holmes, D., 191,202(95) Honbo, K., 233,238(134)
AUTHOR INDEX Horton, D.,48, 170(15), 181, 183,201(30,40, 48). 288,308(44) Hotta, K., 191,203(127-128) Hough, L., 239(148), 243,244,252 Housley, T. L., 216,233,237(73) Huh, C. S., 234,238(142) Hukins, D. W. L., 272,323,373,377,378,383, 402(43,53), 404( 107) Husemann, E., 347,403(94) Hutson, D. H., 181, 183,201(30)
I Ibrahim, S. A,, 234,238(140) Ikunaga, M., 215, 236(61) Imanishi, T., 228,238(117) 1mberty.A.. 322,340,342,402(26-27). 465, 470(70) Internarional Tabfes for X-my Crystuilogruphy. 3 19,364,401(15) International Union of Biochemistry and Molecular Biology, 47, 169(2) Irvine, J.C.,211, 219,235(13),242,244 Isaac, D. H., 323,378. 379,381,382,383, 402(49,52) Isacgarcia, J., 191,204(163) Iseki, M., 222,237(92) Ishida, H., 191, 193,203(98, 100, 121, 123-131). 204(136, 145) Ishizu, A., 278, 308(29) Isogai.Y., 191,203(125, 130) Ito,Y., 180, 184, 186, 191, 198,200(1), 202(57,59),203(132), 204(138) Itoh, K., 191,203(128) IUB Nomenclature Committee, 47,50, 80, 169(9), 170(23) IUPAC Commission on Macromolecular Nomenclature, 52, 170(20) IUPAC Commission on the Nomenclature of Organic Chemistry, 47,49, 129, 146, 149, 169(1), 170(25), 171(27) IUPAC-IUB Commission on Biochemical Nomenclature, 47,50, 113, 142, 169(8), 170(24),321,403(62) IUPAC-IUB Joint Commission on Biochemical Nomenclature, 47,52,57,68,9I , 95.97, 154, 159, 163, 168, 169(3-7, 10-ll), 170(12,21) IUPAC-IUBMB Recommendations for Carbohydrate Nomenclature, 208, 235(4)
475
IUPAC Nomenclature of Organic Chemistry, 47, 53,68, 86,87, 88,91,92, 106, 11 1, 116, 123, 134, 141, 142, 145, 146, 170(13,26) IUPAC-IUB Commission on Biochemical Nomenclature, 47,49, 149, 169(1) Iwanow, A,, 287,308(39) Iwata, C., 228,238(117)
J Jackman, L. M., 212,235(25) Jackson, R. F.,210, 211,232, 235(7, 12, 16-17), 238(122), 242,243,244,457, 469(44) Jacquinet, J. C., 383,404(109) Jain,R. K., 191,204(133-135, 148, 162) James, K., 180, 183,201(25) Jarvis, M. C., 225,238(112) Jeffrey, G. A,, 227,238(115) Jennings, H. J., 181, 186,201(34),202(76) Jensen, L. H., 312,401(1) Jimenez-Barbero, J., 370,404(105) JimCnez Blanco, J. L., 239(150), 260,261,262, 263,265 Jin, H., 185,202(70) Johnson, D. C., 445,468( 18) Johnson, E., 278,308(24) Jones, R. E., 217,237(77) Jordan, K. L., 191,204(149) Joming, W. P. A,, 191,204(165) Joyce. G . F., 307,309(83) Joyce, K., 323,386,402(55) Julliard, J. H., 277,284, 305,308(23), 309(80) Junk, W. R., 460,462,469(56) Juritz, J. W. F., 339,403(82)
K Kadoma, M., 233,238(134) Kahne, D., 191, 199,204(161), 204(143), 205(185-187) Kainuma, K., 214,215,233, 236(42-43, 65-66), 238(134) Kamata, A., 233,238(130) Kamerling, J. P., 191,204(139),205(175) Kameyama,A., 191,203(128),204(136) Kanamoto, M., 215,237(70) Kaneuchi, C., 233,238(135) Kang, S. I., 214,236(45-46) Kanie, O., 191,204(137-138)
476
AUTHOR INDEX
Kanters, J. A., 212,226, 228, 235(28-29) Karigane, T., 215,236(56-57) Kasai, N., 322,356,358,402(34), 403(99) Kato, M., 191,203( 126) Katsuragi, T., 233,234,238(132), 239(145) Kawaguchi, H., 214,236(55) Kawaguchi, M., 191,205(170) Kawamura, M., 213,214,220,236(41,44) Kawasaki, T., 305,309(75), 309(79) Keiboom, A. P. G., 450,453,455,468(27-30) Kelly, F. H. C., 441,444,455,457,458,468(1) Kennedy, I. A., 278,281,287,308(27,41) Kerekes, I., 217,237(78-79) Kerekgyarto, J., 191,204(139- 140), 205(175) Keresztezy, J. C., 271, 307(2) Khan, S. H., 191,204(141) Kharin, S. E., 457,469(45) Khedair, K. A,, 225,238(110) Kihlberg, J., 191, 204(142) Kim,% H., 191, 199,204(143),205(187) Kim, S. I., 214,236(4546) Kinzy, W., 180, 193, 198,201(18) Kirkley, D. N., 276,307(15, 17) Kishimoto, M., 214,233,236(42-43), 238(134) Kiso,M., 191, 192, 193,203(97-98, 100, 121- 132), 204( 136- 137,144- 143, 20% 172- 173, 178) Kitagaki, M., 215,236(61) Kitahata, S., 214,215,236(49), 236(63-64) Kitamura, S., 191,204(168), 205(169-171) Klares, U., 191,204(147) Klemer, A., 288,308(43) Klirnov, E. M., 186,202(78) Knirel, Y.A., 216, 237(75) Knoop, H., 213,216,232,235(32) Knorr, E., 180, 183,201(19) Kobayashi, S., 213,214,215,233.235(36), 236(42-43,65-66). 238(134) Kobori, H., 213,214,236(40) Kochetkov, N. K., 186, 191,202(78),204(153) Koenigs, W., 180, 183,201(19) Kolpak, F. J., 322, 330,401(20) Komba, S., 191,203(127) Kondo, T., 233,238(132- 133) Konradsson, P., 181, 184, 186, 189,201(26), 202(82,90) Koto, S., 224,237(106) Kovac,P., 191,204(146) Kozluk,T., 231, 238(121) Krauss, N., 33 1,403(74) Kreis, U. C., 191,204(149)
Kroon, J., 212,226,228,235(28-29) Kubo, N., 214,236(42) Kulkami, V. R., 186,202(80) Kurnaoka, H., 276,291,303.305,306,307(19). 308(49), 309(68-73.78.81) Kunz, H., 180, 181,200(10), 201(28) Kuppel, A., 347,403(94) Kuramoto, K., 214,236(49) Kurarnoto, T., 215,236(63-64) Kurudis, S., 462,469(60) Kusano, H., 233,238(130) Kushibe, S., 215,237(68) Kuster, B. F. M., 457,469(47-48) Kusui, S., 215,236(59) Kusumoto, S., 191,202( 115) Kuzuhara, H., 191,204(167)
L Lacombe, J. M., 183, 201(55) Lai, Y. Z., 445,468( 17) Langenhoff, F.,I8 1,201(43) Latham, A. B. M., 464,469(65) Lee, D. M., 332,403(77-78) Lee, D. T., 234,238(141) Lee, E. J., 313,322,323,362, 384,389,401(7), 402(39,57,61), 404(111) Lehong, N., 185,202(65) Lelliott, C., 338,339,403(82) Lemieux, R. A., 465,470(71) Lemieux, R. U., 180, 181, 183, 184,200(4), 201(22,25,38-39),212,224,226,227, 235(24), 237(105- 106). 238(109), 250 Lergenmuller, M., 191,204(147) Lesieur, M., 271,294,307(5) Leslie, R., 191, 203(110) Letellier, M., 190, 198,202(93) Levenberg, B., 297,309(62) Lewis, T. A,, 455,469(39) Ley,S. V., 191, 199,203(110),205(188) Lichtenthaler, F. W., 191, 204(147) Lim, K. S., 234,238(142) Lindberg, A. A., 180,200( 1 1 ) Lindberg, B., 232,238(122), 242,445,468(16) Linnett, P. E., 273,288,289,307(6), 308(46-47) Lipkind, G. M.. 191,204( 153) Liptak, A., 191,204(139-140, 166). 205(175) Litchfield, G. J., 299,309(66) Litt, M. H., 332.403(78)
AUTHOR INDEX Little, M., 181, 201(32) Liu, X. G., 191,204(148) Llewellyn, D. R., 455,469(39) Locke, R. D., 191,204(134) Lonn, H., 186, 187, 191, 198,202(71-74). 203 (105, 108, 116, 120). 204(155) Lonsdale, D. M., 307,309(84a) Lopez, J. C., 181,201(27) Lopezbarba, E., 191,203(112-113) Love, S. M., 297,309(62) Lutz, B., 212,226,228,235(28-29)
M Mackie, W., 322, 335,338,353,401(23), 402(32 - 33) Maclean, D. B., 191,205(181) Magasanik, B., 305, 309(77) Magnusson, G., 191, 192,203(102) Maki, K., 191,205(169) Mallet, J. M., 186, 187, 189, 193, 202(85, 89) Malysheva, N. N., 186,202(78) Manley-Harris, M., 219,222,223,229,230, 23 1,232,234,237(83,93,95,98, 100-101), 242,243,244,245,246,249, 250,253,254,255,257,259,446,447, 449,468(22-23) Marchessault, R. H., 312, 322,332,338-339, 347,358,361,401(2-6), 402(25,35-36), 403(76,80,83,93,98) Marcussen, I., 191,204(152) Marra, A., 186, 187,202(85) Marshall, Jr., E. K., 299,309(65) Marshall, W. L., 464,469(66) Martin, 0. R., 228,238(118) Mashiko, M., 215,237(70) Mathews, J. A., 457,469(44) Mathews, M. B., 378,404(107) Mathlouthi, M., 212,226,228, 235(28-29) Matsunaga, H., 329,403(69) Matsuyarna, T., 215,216,237(69-72). 243,244 Matsuzaki, K., 180, 184, 200(1) Matta, K. L., 191,204(133-135, 141, 148, 162) Mauch, W., 441,444,449,462,468(2), 469(60) Maurandi, V.,444,468(7) McCloskey, C. M., 445,468( 19) McDonald, E. J., 207,210,211,232,235(1,7, 16-18), 243,457,469(43) McDonald, M. P., 465,470(68)
477
McKellar, R. C., 234,238( 143) McMordie, A. S., 28 1,308(30) McMordie, S., 306,309(82) McNab, C. G. A., 322,362,402(30) Meade, G. P., 460,462,469(54) Mega, T. L., 455,469(41) Mehta, S., 191, 199,203(103), 204(149), 205(189) Melaja, A. J., 232, 233,238(125) Mellet, C. 0.. 191, 204(150) Mereyala, H. B., 186, 191,202(80), 204(151) Metras, F., 231,238(120) Meyer, C., 465,470(70) Meyer, K. H., 326,403(65) Michon, V., 189, 193,202(89) Millane, R. P., 318, 322,323,337,366,378, 379,383,386,401(8-10,24), 402(41,50, 54) Miller, D. P., 335,403(81) Miller, R., 217,237(77) Misch, L., 326,403(65) Mitchell, D. J., 224,238(108) Mitra, A. K., 323, 374, 375, 377, 378, 379, 382, 383,402(44-45,48,50,52) Mitsuoka, T., 233,234,238(135, 139) Miura, Y., 214, 236(47) Miyazaki, H., 191,205(177) Modler, H. W., 234,238( 143) Mok, W. S. L., 458,469(49) Molina, J. M., 191, 203(113) Moller, B. L., 191,204(152) Montgomery, R., 444,468(12) Moody, W., 446.447.449,468(24) Moorhouse, R., 322, 323,369,372, 373, 377, 395,396,402(42-43,58,60), 404( 114) Mootoo, D. R., 181, 184, 189, 201(26), 202(90) Mori, M., 184, 198, 202(57) Morirnoto, Y., 215,236(67), 237(68) Morisaki, M., 303,305,306,309(68,81), 309(78) Moritani, Y., 228, 238( 117) Moms, E. R., 355,383,403(97), 404(108) Morten, H.,463,469(63) Mosinger, E. M., 191,205(176) Motawia, M. S., 191,204(152) Moyed, H. S . , 305,309(74) Muggli, R.,329,330,403(66) Mukaiyama, T., 180, 184, 185,201(23), 202(63) Murai,Y., 180, 184,201(23) Murandi, S., 444,468(7) Murata, Y., 191,204(168)
478
AUTHOR INDEX
N Nagahama, T., 191, 192,203(97. 123) Nagamura, S., 215,236(57) Nagarajan, R.,212,226,227,235(24),250 Nagata, K., 233,238(134) Nagayoshi, K., 191,205(171) Nagy,Z. S., 180, 183,201(20) Nakahara, Y., 180, 184,200(1) Nakajirna, Y., 220,222,237(87), 254,257 Nakamura, K., 276, 307(19) Nakatsuki, T., 185,202(63) Nakayama, M., 214,236(51-53). 243,244 Nashed, M., 185,202(61) Newell, P. C., 292,300,308(51-54) Nicolaou, K. C., 180, 184, 185, 198,201(24), 202(68) Nieduzynski, I. A., 322,353,402(32-33) Nifantev, N. E., 191,204(153) Nijkamp, H. J. J., 305,309(76) Nilsson, M., 191,204(154) Nilsson, U., 191, 192,203(102) Nishikawa, S., 215,236(56) Nishimura, A,, 233,234,238(132- 133), 239( 145) Nishimura, K., 191,205(171) Nishio, K., 220,222,237(87), 254,257 Nitsch, E., 227,238(115) Niwa, S., 213,236(38) Nojima, M., 217,237(78-79) Norberg,T., 181, 185, 189, 191,201(31), 202(69,87), 203(105, 116, 120). 204(155) Nose, T., 305.309(75) Numata, M., 191,203(114) Nunez, H. K., 295,296,299,303,308(59)
0 O’Donnell, G. W., 445,446,447,449,468(20) Ogawa, H., 191,203(121) Ogawa, K., 322,356, 361,402(38),403(98) 0gawa.T.. 180, 181, 184, 186, 191, 198,200(1), 201(35), 202(57,79), 203(114), 204(138, 156) 0gihara.Y.. 191,203(119) Ogura, H., 186,202(84) Ohki, H.,191, 192,202(97) Ohkishi, H., 215,236(67), 237(68) Ohno. K., 214,236(55) Ohta,Y., 191,203(129-130) Okamura, K., 322, 361,402(38)
Okuyama, K., 322,356,395,402(34),404(114) Olah, G. A., 217,237(78-79) Olah, J. A,, 217,237(79) Oldfield, J. F. T., 444,468(9) Olea, D. P., 191,203(113) Oleinik, I. A,, 444,468(8) Olmstead, L. J., 232,238(126) Olsen, C. E., 191,204(152) Ontto, D. E., 445,468(17) Orban, J. I., 223,234,237( 103) Ortiz Mellet, C., 239(150), 260,261,262,263, 265 Oscarson, S., 183, 186, 190, 191, 198,202(56, 86). 203(101,118), 205(184) Otsubo. A., 322,356,402(34 Overend, W. G., 14,445,468(13) Ozawa, M., 322,356,402(34)
P Pacak, J., 183,201(50) Pacsu, E., 181,201(49) Pakulski, 2.. 183,201(54) Pancoast, H.M., 460,462,469(56) Papahatjis, D. P., 180, 184, 185, 198,201(24), 202(68) Paradossi, G., 335,403(81) Parker, K. D., 322,353,361,402(32-33,37), 404( 101) Parker, K. J., 444,449,460,462,468( 1 1) Patterson, J. A., 223,234,237( 103) Pauloski, R. M., 287,308(41) Paulsen, H., 180, 191,200(7-8, 13). 204(157), 458,459,469(51a) Pavia, A. A,, 183,201(55) Pedersen, C., 212,213,216,217,218,219,220, 22 1,223,225,226,228,229,231,232, 235(31), 237(76,80,82,84), 243,244, 246,247,249,250,25 1 Pedretti, V.,181,201(45) Pennings, N. J., 296,308(60) Pepperman, A. B., 462,469(59b) Ptrez, S., 322,335,340,342,370,402(26-27). 403(81), 404(105) Perron, F., 224,225,228,231,237(104) Persson, J., 330,403(70) Peters.T., 191, 203(104), 204(158) Petitou, M., 383,404(109) Pfannerniiller, B., 344,403(90) Pfeffer, P., 227,238( 115)
AUTHOR INDEX Pflughaupt, K. W., 458,459,469(51a) Pictet, A., 210,235(5), 242 Pierozynski, D., 183,201(54) Pigman, W., 457,458,469(42) Pilotti, A., 198,202(75) Pinto, B. M., 191, 199,202(103), 204(149), 2 0 3 189) Piskorz, C. E, 191,204(133, 135) Plokhikh, I. A., 444,468(8) Pollock, C. J., 216,233,237(73) Pople, J. A,, 72, 170(22), 226,238( 114) Poppe, L., 465,470(69) Pothier, N., 225,228,238( 11 1) Pozsgay,V., 181, 186, 191,201(34), 202(76), 204(159- 160) Praly, J. P., 224, 238(109) Preston, R. D., 34,335,337, 361,403(79, 404( 101) Probiotics: the Scientific Basis, 234, 238(144) Provasoli, A., 383,404(109) Puigjaner, L. C., 323,386,402(55)
R Radha, A., 313,320,323,383,389,393,401(7, 16).402(56-57). 404( 110) Rafka, R. J., 228,238( 118) Ragazzi, M., 383,404( 109) Raghavan, S., 191, 199,204(161), 205(186) Raghunathan, S., 323,375,377,402(45,48) Rakotomanomana, N., 183,201(55) Randall, J. L., 180, 184, 198,201(24) Rauwald, W., 191,204(157) Ravenscroft, M., 185,202(59) Readshaw, S. A., 225,23811 10) Rearick, D. E., 232,238(126) Reddy, B. S., 233,238(136) Reddy, G. V., 186, 191,202(80), 204(162) Rees, D. A,, 322,323,355,366,369,372,373, 377,383,402(40,4243,53), 403(97), 404( 108) Renaut, J., 291,308(50) Reynolds, D. D., 180,200(2) Richards, G. N., 2 19,222,223,229.230.23 1, 232,234,237(83,93,95,98, 100- 103). 242,243,244,245,246,249,250, 253, 254,255,257,259,446,447,449,455, 458,461,462,468(2&24), 469(40,49) Richardson, A. C., 239(148), 243,244,252 Richardson, E. M., 285,308(38)
479
Rit2en.H.. 191,203(101, 118) Rivenson, A,, 233,238( 136) Robbins, J. B., 191,204(160) Roberts, E. J., 444,468(5) Roberts, R. M. G., 185,202(59) Robina, I., 191,203(112-113) Robinson, D. H., 294,308(55) Roblesdiaz, R., 191,204(163) Rochas, C., 370,404(105) Roche, E., 332,403(76) Rodemeyer, G., 288,308(43) Rohle, G., 180,200(3) RosCn, G., 183, 186, 190, 198,202(56,86) Rosenblatt, J. E., 234, 238(141) Rowan, D. D., 225,228,238( 111) Roy, R., 181, 183, 190, 198, 201(47, 52), 202(93) Rudolph, F. B., 274,276,305,307(1 I - 12) Rugg, P. W., 294,308(55) Rules of carbohydrate nomenclature, 49, 170(17- 19)
S Saenger, W., 331,344,403(74,90) Saha, R., 191,204(148) Saiki, K., 306, 309(81) Sakata, M., 183,201(51) Sandmann, C., 331,403(74) Sanemori, H., 305,309(79) Sanigar, K. M. A,, 463,469(63) Santoyogonzalez, F., 191,204(163) Sapronov, A. R., 457,469(45) Sark0.A.. 312,319,322,326, 329,330, 331, 332,340,342,345,346,347,358,361, 401(2, 14), 402(28-29,35-36,38), 403(63-64,66-67,73,75,84-87, 92-93) Sasajima, K., 278,281,283,308(26,34) Sashida, R., 215,236(67), 237(68) Sato, N., 186,202(84) Sato, S., 194, 198,202(57) Saunders, J. K., 225,228,238(11 1) SauvB, T., 225,228,238( 111) Sawada, M., 212,235(19), 243 Sayer, B. G., 287,308(39-41) Schlubach, H. H., 210, 213,216,232, 235(6,32), 242,244 Schmidt, R. R., 180, 183, 198,200(9, 12), 201(15, 18)
480
AUTHOR INDEX
Schneerson, R., 191,204(160) Schneider, W., 181,201(42) Schnelle, R. E., 239(151), 260,261,262,263, 264,266 Schouten, A,, 212,226,235(28) Schultz, M., 181,201(28) Schwidetzky, S., 191, 204(147) Scott, W. E., 319.319(1 I), 322,369,402(42) Sedmera, P.,239( 149), 243,244,246,247,249, 252 Seitz, S. P., 185,202(68) Seki, K., 214,215,233,236(42-43,65-66), 238( 134) Sen,A. K., 191,205(181) Sepp, J., 181,201(42) Serianni,A. S., 295,296,299,303,308(59-60) Shafer, S. E., 370,404(104) Shafizadeh, F.,14 Shaiu, L. D., 233,238(129) Shashkov,A. S . , 191,204(153) Shaw, G., 294,299,308(55), 309(66) Shaw, P. E., 444,449,468(3) Sheehan, J. K., 323,374,375,377,402(44-45), 404( 106) Sheldrick, B., 322,335,338,401(23) Shilling,W. L., 210,221.235(9), 242,457, 469(46) Shirnizu, J., 186,202(84) Shive, W.. 276,307(18) Shoda, S., 180, 184, 185,201(23),202(63) Shohji, K., 214,236(55) Shomonishi, M., 215,236(61) Shore, M., 444,468(9) Silin, P. M., 460,462,469(55) Silwanis, B. A,, 183, 186, 190, 198,202(56,86) Sinay, P., 180, 18 I , 186, 187, 189, 193,200(5), 201(14,45), 202(85,89), 383,404(109) Sincharoenkul,L. V., 239( 148). 243,244,252 Slechta, L., 278,308(24) Sliedregt,L. A. J. M., 190, 191, 202(94), 204( 164) Smid, P., 191,204(165) Smith, F., I8,212,219,235(23), 243 Smith, P. J. C., 319,323,355,372,373,375, 377,401(13). 402(43.46), 403(97) Smolko, E. E., 322,353.402(32-33) Soler, A., 222,237(91) Sonobe, K., 215,237(69) Southwick, J., 326,403(63) Spencer, G. L., 460,462,469(54)
Spenser, I. D., 273,274,278,281,287,289, 290,307(7-8, lo), 308(27,39-42.48) Stacey, M., 2.5, 8, 14, 18 Steifa, M., 344,403(90) Steiner, T., 331,403(74) Stephen,A. M., 338-339,403(82) Sternhell, S., 212,235(25) Stevens, E. S., 370,383,404(108), 404(104) Stevenson, J. W.. 21 1,219,235(13),242,244 Stick, R., 180, 183,201(25) Stiehler, O., 181,201(42) Stipanovic,A. J., 33 1.332,403(73,75) Stout, G. H., 312,401(1) Stouthamer, A. H., 305,309(76) Streight, H. R. L., 2 1I. 232,23314) Strepkov, S. M., 213,216,235(33), 243-244 Sugimoto. M., 191,203(114) Sugiura, M., 307,309(84b) Sugiyama,J., 330,403(70-72) Sundararajan,P. R., 312,338,339,356, 401(3-6). 403(83,98) Sutton, A. L., 223,234,237(103) Suzukamo, G., 221,237(90), 243,246,251 Suzuki, A., 186,202(84) Suzuki,Y., 214,236(54) Svahn, C. M., 191,204(154) Symposium on Refinery Losses, 455,468(34) Szarek, W. A., 191,205(181), 228,238(118) Szeja, W., 183,201(53) Szonyi, M., 191,203(118) Szurmai, Z., 191,204(166),204(140)
T Takahashi, S., 191,204(167), 214,236(44) Takahashi,T., 191,205(177) Takahashi, Y.,329,403(69) Takao, S., 214,236(47) Takeda, K., 186,202(84) Takeda,T., 180, 184, 191,201(22),203(119) Takeo, K., 191,204(168),205( 169- 171) Takizawa, T., 233,2381 137) Talley, E. A., 180,200(2) Tamura, K., 214,215,236(49,63-64) Tanaka, K., 213,214,215,216,220,222, 236(37-38.40-41.54-62). 237(69-72, 92). 243, 244 Tanaka, M., 220,222,237(87), 254,257 Tanaka, T., 212,213,214,235(19), 236(40), 243
AUTHOR INDEX Taniguchi,T., 212, 235(19, 21). 243 Tarraga, A., 222,237(91) Tashiro,Y., 233,238(137) Tatsuta, K., 180,201(17) Tatum, J. H., 444,449.468(3) Taylor, G., 383,404(108) Tazuya, K., 276,291,303,306,307(19), 308(49), 309(68-73.81) Tejima, S., 183, 201(51) Tekely, P., 330,403(72) Temmink, H. M. G., 457,469(48) Terada, T., 191.203 172- 173) Terayama,H., 191,204(167) Thailambal, V. G., 322, 323, 362,389, 402(39,56) Theander, O., 445,4681 16) ThCrisod, M., 276,278,279,283,284,297,305, 307(13,16). 308(20-22,35-37), 309(63) Thorn, D., 355,403(97) Tillett, J. G., 185, 202(59) Tipson, R. S . , 295, 308(57) Tokunaga, T., 233,238(137) Tomasik, P., 222,237(97) Tomita, F., 214,236(4748) Tomita, K., 191,203(114) Torii, K., 186,202(84) Tom, G., 383,404(109) Toshima, K., 180,201(17) Tran, V., 228,230,238(116), 322, 340, 342, 402126) Trebin, L. I., 444,468(8) Tropper, F. D., 18 I , 183,201(47,52) Tsai, T. Y. R., 185,202(70) Tschiersky, H., 222,231,237(96) Tsuboyama, K., 186,202(84) Tsukada,Y., 191,203(129-130) Tucker, R. G., 292,300,308(51-54) Turcotte, A. L., 21 1,235(18)
U
Uchimura, A., 191,205(178) Uchiyama,T., 212,213,214,215,216,220, 233.235(19,21,34-35). 236(37-41.44, 50,54), 237(69.72), 238(130), 243,244 Udodong, U. E., 186, 189,202(82,90) Ueda, M., 215,236(67) Upstill, C . , 386,404(112) Urech, F., 455,469(37)
48 1
V van Bekkum, H., 450,453,455,468(27-30) van Boom, I. H., 186, 190, 191, 198,202(81, 83,91,94), 203(109), 204(164-165), 205(174, 176, 179, 182-183) van Cleve, J. W., 185,202(64) van den Bliek, M., 462,469(61) van der Baan, H. S . , 457,469(47) van der Maas, H. J., 212,226,228,235(28-29) van der Marel, G. A,, 190,202(94) van der Poel, P. W., 450,453,455,462,465, 468(27-28, 30), 469(61), 470(72) Van Engen, D., 199,205(185) Van Etten, R. L., 455,469(41) van Halbeek, H., 465,470(69) van Leeuwen, S. H., 186,202(81) Vand, V., 320,401(18) Vandelft, F. L., 191, 203(109) VanderHart, D. L., 330,403(69) Vanderklein, P. A. M., 191,203(109), 205(174, 176) Vandemarel, G. A,, 191,203(109), 204(164-165), 205(174, 176, 179, 182-183) Vandewen, J. G. M., 191,204(139),205(175) Vankar, Y. D., 217,237(79) Veeneman,G. H., 186, 190, 191, 198, 202(81,83,91), 205(174, 182) Vercellotti. 1. R., 462,469(58-59) Verduyn, R., 191,205(176) Vernon, C . A., 455,469(39) Verstraeten, L. M. J., 208,235(3) Vethaviyasar, N., 185,202(62) Veyrikres, A., 181, 201(45) Vile, S., 199,205(188) Vinogradov, E. V., 216,237(75) Virtanen, J. J., 232,233,238(125) Vliegenthart,J. F. G., 191,204(139),205(175) Voisin, D., 224,237(106) Voung, R., 330,403(71) Vukov, K., 444,449,462,468(6)
W Wada,Y., 191,205(169) Walker, J., 273,288,289,307(6), 308(46-47) Walker, S., 199,205(185) Walkinshaw, M. D., 322,323, 348,350,353, 395,402(31,58), 403(96), 404(114)
482
AUTHOR INDEX
Wakes, W., 222,231,237(96) Waterman, R. E., 271,307(2) Webster, D. C., 463,464,469(64) Weckerle, W., 288,308(44) Wedemeyer, K. F., 180, 183,201(21) Weichert, U., 191,204(157) Weidenhagen, R., 444,468(10) Weimar, T., 191,204( 149) Welch, J. T., 217,237(79) Wendler, A,, 191, 192,203(102) Wernig, P., 181,201(28) Westman, J., 191,204(154) Whangbo, M. H., 224,238(108) Whistler, R. L., 444,468(4) White, R. H., 273,274, 276,282, 289,290,305, 307(7-8, 10-12, 14), 308(32-33,48) Wickberg, B.,211,212,232,235(11, 30). 238( 123), 242,244 Widmalm, G., 191, 195, 198,202(99) Wiejak, S., 222,237(97) Wiesner, K., 185,202(70) Wild, D. L., 340,342,403(89) Wilhelm, M. P., 234,238(141) Wilhelmy, L., 455,468(36) Williams, R. R., 271, 307(2) Winter, W. T., 322,323,335,345,372,373, 375,376,377,378,379,381,383,395, 396,402(28,43,46-47,49,5 1,59-60), 404( 108) Wolf, E., 287,308(42) Wolf-Ullish, C., 395,404( 1 14) Wolfe, S., 224,238(108) Wolfrom, M. L., 210,211,212,218,221, 235(8-10.22). 242,243,244,278, 308(28), 457,469(46) Wonacott,A. J., 319,401(12) Wong, E., 181,201(32) Wood, J., 217,237(77) Wood, R. M., 465,470(68) Woodcock, C., 329,403(67) Woodward, R. B., 185,202(66) Woolvin, C. S., 21 1,235(15), 242,244 Wootton, A. E., 444,468(9) WU,H. C. H., 340,342,403(84-85)
Wulff, G., 180,200(3) Wuts, P. G. M., 185,202(67) Wysocka, V., 287,308(39)
Y Yaguchi, M., 234,238( 143) Yamada, H., 191,205(177) Yamada, K., 276.29 1,303,305,306,307(19), 308(49), 309(68-73.78.81) Yamaguchi, F., 215,236(56,59) Yamamoto, M., 291,308(49) Yamauchi, K.,214,236(54) Yamazaki, N., 278,308(29) Yang, D., 191, 199,204(143), 205(187) Yasumoto, M., 191,203(117) Yde, M., 181,201(44) Yeon, Y., 227,238( 115) Yeung, L. L., 191,203(110) Yokota, A., 214,236(47-48). 278,281,283, 308(26,34) Yoshida, K., 278,308(29) Yoshida, M., 191,205(178) Yoshida, N., 215,236(56) Yoshihara, H., 221,237(90), 243,246,251 Younathan, E. S., 212,227,235(26)
z Zabel, V., 344,403(90) Zachystalova, D., 183, 201(50) Zaikov, G. E., l80,200(6) Zamojski, A., 183,201(54) Zegelaarjaarsveld, K., 191,204(164), 205(179) ZemplCn, G., 180, 183,201(20) Zevenhuizen, L. P. T. M., 322, 362,402(39), 404( 102) Zhang, M., 313,401(7) Ziegler, T., 191,205( 180) Zou, W., 191,205(181) Zugenmaier, P., 319, 322,340,345,347, 401(14), 402(30), 403(86,91,94-95) Zuurmond, H. M., 191,205(182-183)
SUBJECT INDEX A
KOH-amylose complex, 346-347 A-Amylose, 340-342,407-408 B-Amylose, 342-344,409 V-Amylose, 345-346,410 Analytical chemistry, 18 Anhydrides intermolecular, acetals intramolecular, 1 18- 120 “Armed-disanned’ concept, 189- 193 Arthrobacter ureafaciens, di-D-fructose dianhydrides and, 213-214 Aspergillusfurnigatus Fresenius, di-D-fructose dianhydrides and, 215 Aspergillus niger, transglycosylation processes, 10
Acetals, nomenclature, 123- 124 cyclic, nomenclature, 121 - 122 Acid degradation, monosaccharides, 457-459 Acid hydrolysis di-D-fructose dianhydrides and per-O-methyl derivatives, 232 sucrose, 455-456 Acyl halides, nomenclature, 105 Agarose, 368-370,420 Aldaric acids, 51, 110-1 12 Alditols. 51, 102- 103 Aldoketoses, nomenclature, 79- 80 Aldonic acids, 51, 103-106 Aldoses acylated, thioglycosides preparation, 181 chiral centers, multiple sets, 73-74 B cyclic forms, anomeric configuration, 74 definition, 50 Bivalent substituent prefixes, 143-145 multiple configurational prefixes, 73 Bragg ’s law, 3 14 systematic names, 72-73 Bratton-Marshall assay, 299 trivial names and structures, 54.72 Aldosuloses, nomenclature, 79-80 Alginic acid, 353-356 C Amides, nomenclature, 104- 105 5-Amino- 1-( P-D-ribofuranosy1)imidazole Calcium chondroitin 4-sulfate, 38 1 -382, biochemical methods, 297-300 425 -426 chemical synthesis, 295-297 Calcium hyaluronate, 376-377 preparation of specifically labeled samples, Calcium pectate, 353 295 - 300 Calcium welan, structure, 432-434 5-Amino-I -(P-D-ribofuranosyl)imidazole5’Candida utilis, thiamine synthesis, phosphate 29 1 derepression of thiamine synthesis, 292-293 Caramels, chemical nature, 222-223 ring expansion, 293-295 Carbohydrates 4-Amino-2-carboxymethyl-5-hydroxymethyldefinition, 49-50 pyrimidine, decarboxylation, 303 medical uses, 10 5-Amino-1-cyclohexylimidazole-4-carboxylic Carbon, ring oxygen replacement by, 14 1 - 143 acid, 299 2-Carboxy-5-(2-hydroxymethyl)-44-Amino-5-hydroxymethyl-2-methylpyrimidine, methylthiazole, synthesis and 268-269 transformations, 284-286 Amino sugars Carrageenans, 366-368,418-419 definition, 5 1 Cellotetraose hemihydrate, 33 1 Maurice Stacey’s work, 15 Cellulose, 326,329-332 nomenclature, 84-86 alternate unit cells, 329-330 polysaccharide derivatives, 166 derivatives, 332 Amylose, 340-349 hydrogen-bonded sheets parallel, 329 derivatives, 347-349 structure, 405 483
484
SUBJECT INDEX
Chemical synthesis, di-D-fructose dianhydrides, 234 Chitin, 333-334,405 Chondroitin sulfate, 378-382,424-426 I3C NMR spectra dianhydride components of glycosyl di-ofructose dianhydrides, 256-257 dihexulose dianhydrides, 245 -246 fructose components di-o-fructose dianhydride derivatives, 262 per-0-acetylated di-o-fructose dianhydride derivatives, 263 per-0-acetyl glycosyl di-o-fructose dianhydrides, 258 glycosyl di-D-fructose dianhydride, 259 per-0-acetyl dihexulose dianhydrides, 247 Curdlan, 356-361 helix structure, 358, 360 parallel packing arrangement, 358-359 structure, 415 Cyclic forms definition, 50 nomenclature, 48-49
N’-Cyclohexyl-a-formylaminoacetamidine, 299 -300
D Deamination, glucosamines, 16 ‘Dehydro’ names, aldoketoses, 80 Deoxyalditols, 83 1-Deoxy-D-erythro-pentulose,synthesis, 288 1-Deoxy-o-lhreo-pentulose biosynthesis problems, 282-284 of pyridoxol, 287 chemical and preparative enzymic syntheses, 278-282 isolation from S. hygroscopicus, 277-278 as precursor of five-carbon chain of thiazole in E. coli, 275-277 stray thiazolic metabolites with probably deoxypentulose origin, 284-287 synthesis from diethyl tartrate, 281 from D-glyceraldehyde, 279 labeled at both ends with deuterium, 279-280 with labeled pentulose, 281 -282
Deoxy sugars chemistry, Maurice Stacey’s work, 14 definition, 5 1 deoxyalditols, 83 names derived from trivial names of sugars, 81 systematic names, 81-83 trivial names, 80-81 Dermatan 4-sulfate, 382-383 Desosamine, Maurice Stacey’s work, 14- 15 Dextrans, Maurice Stacey’s work, 8-9 Dialdoses, 50.74-75 Di(3-deoxy-o-g~ycero-pentuIose) 1,2’:2,1 dianhydride, 227 Di-D-fructose dianhydrides acid hydrolysis, 232 in chemical synthesis, 234 derivatives, 260 optical rotations and melting points, 261 from higher plants, 213 industry and, 232-233 microorganisms and, 213-216 ”C NMR spectra, fructose components, 262 ‘H NMR spectra, 264 nutrition and, 233-234 per-0-acetyl derivatives, IH NMR spectra of fructose components, 265 -266 Difructose anhydrides, 21 1-212,240 formation, 219 Diheterolevulosans, 209-21 1,240 Dihexulose dianhydrides, 207-266, see also Caramels; Di-D-fructose dianhydrides I3C NMR spectra, 245-246 conformation, electronic control, 224-228 conformational rigidity, energetic outcomes, 228 hexulopyranose rings, 226 historical overview, 210-213 ‘H NMR spectra, 248-249 intramolecular hydrogen-bonds, 227 isomerization, 23 1-232 1,2-linked, exo-anomeric effect, 224-225 listing, 240-241 nomenclature, 208-210 optical rotations and melting points, 242-243 protonic activation using anhydrous hydrogen fluoride, 216-220 with acids other than HF,221 I-
SUBJECT INDEX from spirodioxany I pseudo-oligosaccharides, 220-221 thermal activation in presence of acids, 22 1 without acids, 221 thermodynamic versus kinetic control of product distributions, 228-232 three spiro-linked rings, 225-226 1,6-Dihydroxy-2-hexanone,dimerization products, 228-229 Diketoses, 50,78-79 1,7-Dioxaspiro[5.5]undecane,224 Disaccharides definition, 148 with free hemiacetal group, 149- 150 trivial names, 150- 151 without free hemiacetal groups, 148- 149 Dische test, 13 Dithiocetals, thioglycosides preparation, 181 DNA, disaggregation, ultrasonic irradiation, 1 1 Double bonds, unsaturated monosaccharides, 92-95 cumulative, 95 -96
E Enantiomers, cyclic monosaccharides, 72 Escher-ichia roli M41 capsular polysaccharide, 396-398 structure, 434-437 synthesis of five-carbon chain of thiazole, 275-277
F Feulgen reaction, 13 Fischer, Emil, contributions to nomenclature, 48 Fischer projection, monosaccharides acyclic form, 56-57 cyclic forms, 59-60 modified, 60-61 Fluorine chemistry, 18- 19 D-Fructofuranosides, degradation, 445 Fructofuranosyl cation, 2 17 Fructofuranosyl fluorides, 217 Fructose decomposition in water, products, 458 dihexulose dianhydrides from, 217-218
485 G
Galactoglucan, 362-364,417-418 Galactomannans, 395-396 y-radiation, effects on saccharides, 17 Gellan, 385-391 (1+3)-a-D-Glucan, 361 -362,416 (1 +3)-P-D-Gh~an, 356-361 P-o-Glucopyranosides, alkaline degradation, 444-445 D-Glucose, catahol ism %on-oxidative pathway”, 289-290 “oxidative pathway”, 289 Glycopeptides. 167- 168 Glycoproteins. 167- 168 Glycose-based terms, 177 Glycosidation methods, oligosaccharide synthesis, 179- 182 Glycosides, 51, 132-135 Glycosidic oxygen, catalysis, protonation by hydrated magnesium ions, 461 -462 Glycosylamines, nomenclature, 137- 139 C-Glycosyl compounds, nomenclature, 139- 140 Glycosyl di-D-fructose dianhydrides, 254 I3C NMR spectra, 259 dianhydride components, 256-257 optical rotations and melting points, 255 Glycosyl donors, 186- 187 Glycosylfructoses, treatment with hydrogen fluoride, 230 pyridinium poly(hydrogen fluoride), 229 Glycosyl halides in siru generation from thioglycosides, 184-185 nomenclature, 136- 137 thioglycosides preparation, 181 Glycosyl piperidine carhodithioates, acetylated, thioglycosides preparation, 183 Glycosyl residues, nomenclature, 125 Glycosyl sulfones, as glycosyl donors, 199200 Glycosyl sulfoxides. as glycosyl donors, 199-200 Glycosyl thiocyanates, thioglycosides preparation, 183 Glycosyl xanthates, thioglycosides preparation, 183 Gram-staining process, study, 12
486
SUBJECT INDEX
H Haworth representation, cyclic monosaccharides, 61 -63 Hemiacetal groups disaccharides with, 149- 150 without, 148- 149 nomenclature, 122- 123 oligosaccharides with, 153-154 without, 151-153 Hemiketals, nomenclature, 122- 123 Heparin, Maurice Stacey's work, 11 Histidine pyridoxol pathway, 305 'H NMR spectra di-o-fructose dianhydride derivatives, 264 per-0-acetyl derivatives, fructose components 265-266 dihexulose dianhydrides, 248 -249 per-0-acetyl dihexulose dianhydrides, 250-251 per-0-acetyl fructose glucose, 252 Homopolysaccharides, nomenclature, 163 Hyaluronan, 370-378,421 3-fold helix, 375-378 4-fold helix, 372-375 segment, 37 1 Hyaluronic acid, see Hyaluronan Hydrogen fluoride, 216 anhydrous, protonic activation of dihexulose dianhydrides, 216-220 Hydrogensulfite, thiamine cleavage, 27 1 272 4-Hydroxy-~-threonine,pyridoxol biosynthesis, 287 S-(HydroxymethyI)-2-furaldehyde,formation, 457-458
I Imidazole, ring expansion, 293-295 Inulin caramels, 222-223 dihexulose dianhydrides from, 2 17-2 18 thermal activation, 222 Inulin fructotransferase, microorganisms and, 214-215 Invert sugar, 449
K Keratan 6-sulfate, 383-384,427 Ketals, nomenclature, 123- 124 Ketoaldonic acids, 51, 106-107 Ketoaldoses, 51.79-80 Ketoses classification, 75 configurational prefixes, 76-77 definition, 50 systematic names, 75-76 trivial names, 75 KOH-amylose, 346-347,410-411
L Lactones, nomenclature, 105 Linked-Atom Least-Squares analysis, 3 19 Lithium gellan, 386 Luteic acid, 8
M Maillard reaction, 458-459 Mannan, 334-338 antiparallel packing arrangement, 335-336 packing arrangement, 337-338 structure, 406 X-ray diffraction pattern, 334-335 Mass spectra, partial, per-0-trimethylsilylated dihexulose dianhydrides, 253 meso forms aldaric acids, 1 10- 111 monosaccharides, 59 Methyl 3,4-di-0-methyl-cu-D-fructofuranoside, 445 Methyl-o-fructofuranosides, 445 -447 4-Methyl-5-(2-hydroxyethyl)thiazole, 268-269 0-Methylsucroses, degradation, 447 Methyl triflate, 187 Microorganisms, di-o-fructose dianhydrides and, 213-216 Mills depiction, cyclic monosaccharides, 63 Monosaccharides, see also Aldoses acid degradation, 457-459 alkaline degradation, 449-455 mechanisms, 451
SUBJECT INDEX reaction model, 453-454 anomers center of chirality, 65 mixtures, 67 reference atom and configurational symbol, 65-67 use of a and p, 68 bivalent and tervalent groups, 128 branched-chain naming branches, 101 numbering, 101 parent choice, 98- 101 systematic names, 98 terminal substitution, I01 trivial names, 97-98 configurational atom, 57-58 configurational prefixes in systematic names, 58-59 cyclic forms conformational descriptor, 68-69 conformation depiction, 63 -64 conformations of chains, 64 enantiomers, 72 Fischer projection, 59-60 Haworth projection, 61 -63 Mills depiction, 63 modified Fischer projection, 60-61 ring shape notation, 69 ring size, 59 unconventional Haworth representations, 63 variant notation, 69-72 definition, 50 Fischer projection of acyclic form, 56-57 glycosides, 132- 135 C-glycosyl compounds, 139- 140 N-glycosyl derivatives, 137-139 glycosyl halides, 136- 137 glycosyl residues, 125 isotopic substitution and isotopic labelling, 9 I mem forms, 59 optical rotation, 59 parent structure choice, 53 numbering and naming, 53-56 racemates, 59 radical ions, 131-132 radicals, 129 replacement of
487
carbonyl oxygen by nitrogen, 89-90 hydrogen at non-terminal carbon atom, 87-88 OH at non-terminal, non-anomeric carbon atom, 88 ring oxygen replacement by carbon, 141 - 143 nitrogen or phosphorus, 140- 141 selenoglycosides, 136 as substituent groups, 125- 128 terminal substitution, 89 thioglycosides, 135- 136 trivial names with systematic equivalents, 172-176 unequal substitution at non-terminal carbon atom, 88-89 unsaturated, 91 double bonds, 92-95 triple bonds and cumulative double bonds, 9.5-96 use of D and L, 57 Mycohucteriurn tuberculosis, polysaccharides from, Maurice Stacey’s work. 7-8
N Nitrogen, ring oxygen replacement by, 140- 141 Nomenclature, 44- 177, see also Monosaccharides; Oligosaccharides; Polysaccharides acetals, ketals and thio analogues, 123- 124 aldaric acids, 110- 112 alditols, 102- 103 aidonic acids, 103- I06 aldoses, 72-74 amino sugars, 84-86 anhydrides intermolecular, 120- 121 intramolecular, 118- 120 carbohydrates containing additional rings, 143- 147 bivalent substituent prefixes, 143- 145 ring fusion methods, 145- 146 spiro systems, 146- 147 commissions, 49 conventions, 52 cyclic acetals, 121- 122 cyclic forms, 48-49 deoxy sugars, 80-83
SUBJECT INDEX
488
dialdoses, 74-75 diketoses, 78-79 disaccharides, 148- 151 glycosides, 132-135 C-glycosyl compounds, 139- 140 N-glycosyl compounds, 137- 139 glycosyl halides, 136- 137 glycosyl residues, 125 hemiacetals, hemiketals and thio analogues, 122- 123 historical development, 48-49 ketoaldonic acids, 106- 107 ketoaldoses, 79-80 ketoses, 75-77 N-substitution, 117- I18 0-substitution, 112- I17 radical ions, 131- 132 radicals, 129 ring oxygen replacement bycarbon, 141-143 by nitrogen or phosphorus, 140- 141 selenoglycosides, 136 sulfates, 11 6 1 17 thioglycosides, 135-136 thio sugars and chalcogen analogues, 86-87 trivial names with systematic equivalents, 172-176 uronic acids, 108- 1 10 N-substitution, nomenclature, 117- 118 Nutrition, di-D-fructose dianhydrides and, 233-234
0 Oligosaccharides analogues, 158- 159 block synthesis, thioglycosides in, 191 - 198 branched, 155-156 cyclic, 156-158 definition, 52 with free hemiacetal group, 153- 154 linkage analysis, 17- 18 symbols for defining structures condensed form, 16 I - 162 extended form, 161 short form, 162- 163 sugar chain representation, 159 symbols, 160 synthesis glycosidation methods, 179- 182
thioglycosides as glycosyl acceptors, 197-198 without free hemiacetal groups, 151-153 @substitution, nomenclature, 112- 1 17 acyl, 112-113 phosphates, 113-115 phosphinates, 116 phosphonates, 115- 1 I 6
P Paper ionophoresis, sugars, Maurice Stacey's work, 17 Pectic acid, 350, 352,414 Pectin, 348,350-353 Pectinic acid, 353 Pentulose, synthesis, 281 D-erythro-Pentulose 5-phosphate, 289 Peptidoglycans, 167- 168 Per-0-acetylated di-D-fructose dianhydride derivatives "C NMR spectra of the fructose components, 263 Per-0-acetyl dihexulose dianhydrides I3C NMR spectra, 247 'HNMR spectra, 250-251 optical rotations and melting points, 244 Per-0-acetyl fructose glucose, 'H-NMR spectra, 252 Per-0-acetyi glycosyl di-D-fructose dianhydrides, I3CNMR spectra of fructose components, 258 Per-0-methyl derivatives, acid hydrolysis, 232 Per-0-trimethylsilylated dihexulose dianhydrides, partial mass spectra, 253 pH, control and measurement in sugar refining, 464-466 Phosphates, nomenclature, 113 - 115 Phosphinates, nomenclature, 1 16 Phosphonates, nomenclature, 115- 116 Phosphorus, ring oxygen replacement by, 140-141 Phosphorus oxoacid esters, nomenclature, 113- 1 I6 Pneumococcirs, polysaccharides from, 6-7 Poly(a-L-guluronic acid), 353, 355-356,415 Poly(P-D-mannuronic acid), 353-354.414 Polysaccharides, 3 I 1-439 amino sugar derivatives, 166 chemical repeating units, 321, 324-325
SUBJECT INDEX composed of more than one kind of residue, 166- 167 crystallographic data, 321 -323 definition, 52 gellan family, 383-393.428-431 helical parameters and conformation angles, 385 welan, 389,391-393.432-434 glycoproteins, glycopeptides and peptidoglycans, 167- 168 helix diffraction theory, 320 homopolysaccharides. I63 linkage analysis, 17-18 linkage designation, 164 (1 +3)-linked, 356-364 galactoglucan, 362-364 (I--'3)-Ct-D-ghCan, 361 -362,416 helical parameters and conformation angles, 357 structure, 417-41 8 (1+3)-P-~-xylan, 361 (1 +4)-linked, 326-356 alginic acid, 353-356 amylose, 34CL349.407-412 cellulose, 326,329-332,405 chitin, 333-334.405 helical parameters and conformation angles, 327-328 mannan, 334-338.406 pectin, 348,350-3.53.413-414 P-o-xylan, 338-339.407 ( I +4),( 1+3)-linked, 364-383 agarose, 368-370,420 cmageenans, 366-368.418-419 chondroitin sulfate, 378-382.424-426 dermatan 4-sulfate, 382- 383 helical parameters and conformation angles, 364-366 hyaluronan, 370-378,421 keratan 6-sulfate, 383-384 from micro-organisms, Maurice Stacey 's work, 6-8 more-branched, 393 -401 E. coli M41 capsular, 396-398,434-437 galactomannans, 395 -396 helical parameters and conformation angles, 394 Rhiz. frifolii capsular, 398-401.437-439 xanthan, 395 newly discovered, nomenclature. 164- 16.5 preparation, 2 13-2 14
489
residue configuration designation, 163 substituted residues, 167 uronic acid derivatives, 165 X-ray diffraction analysis, 314-325 computer model building, 318-320 data presentation, 320-325 Linked-Atom Least-Squares analysis, 3 19 oriented fiber, 316-317 powder pattern, 315 types of diffracting specimens, 314-317 Potassium chondroitin 4-sulfate, 379-38 1,424 Potassium gellan, 386-389,428-429 Potassium hyaluronate 3-fold helix, 377 4-fold helix, 374-375 Potassium native gellan, 389-391,430-431 Pseudo-oligosaccharides,spirodioxanyl, 220-22 1 Pyramine biosynthesis, 305 -306 5-amino- 1-(P-o-ribofuranosyljimidazole pathway, 301-302.305 eukaryote-prokaryote dichotomy, 30.5-306 histidine pyridoxol pathway, 305 degradation, 274 mass-spectrometric fragmentation, 274-275 synthesis imidazole ring expansion, 293-294 in yeasts, 303-306 participation of D-ghCOSe, 303-304 participation of L-histidine and pyridoxol, 303-304 Pyridoxol, biosynthesis, 1 -deoxy-D-fhreopentulose in, 287 Pyrimidine cleavage of bond with thiazole, 271 -272 precursors, biosynthesis of thiamine diphosphate, 269-271
R Reducing sugars alkaline degradation, reaction model, 453-454 enolization, in acid solution, 457 mutarotation and isomerization, 450 L-Rhamnose, Maurice Stacey's work, 13 Rhizopium trifolii, capsular polysaccharide, 398-401
490
SUBJECT INDEX
Ring fusion methods, 145-146 Ring shape, notation, cyclic monosaccharides, 69 Ring size, cyclic monosaccharides, 59
S Selenoglycosides as glycosyl donors, 199 nomenclature, 136 Sodium chondroitin 4-sulfate, 379, 381 Sodium hyaluronate 3-fold helix, 375-376 4-fold helix, 372-374 structure, 421 Sodium pectate, 350,352-353 structure, 413-414 L-Sorbose, dihexulose dianhydrides from, 218-220 Spinach chloroplasts, thiamine synthesis, 277 Spirodioxanyl pseudo-oligosaccharides, 220-221 Spiro systems, nomenclature, 146- 147 Stacey, Maurice, 1- 19 amino sugar work, 15 analytical chemistry, I8 authoring papers, 4 awards, 6, 19 childhood, 1-2 community roles, 3-4 desosamine work, 14- 15 dextran work, 8-9 DNA studies, 1 I - 12 effects of y-radiation on saccharides studies, 17 fluorine chemistry, 18-19 gram-staining reaction studies, 12 horticultural interests, 2 influence of colleagues, 4 Mason professor of chemistry, 3 polysaccharide structure work, 17- 18 promotion of collaborations between universities and industry/govemment, 4 sporting prowess, 4 typhoid fever vaccine work, 6 University of Birmingham, 2-3 vitamin C research, 5-6 Streptornyces hygroscopicus, 1-deox y- D-threopentulose isolation, 277 -278
Sucrose acid hydrolysis, 455-456 caramels, 222-223 degradation, 441 -466 alkaline, 444-449 chloride salts effect, 461 effects on manufacture, 458-466 color from degradation products, 462 control and measurement of pH, 464-466 inversion rates and sucrose loss, 460-464 statistical process control, 463 hydrolysis rates, 460-462 thermal activation, 222 sugar
paper ionophoresis, Maurice Stacey’s work, 17 production flowchart beet, 442,444 cane, 443-444 Sugar chains, representation in oligosaccharides, 159 Sulfates, nomenclature, 116- 117
T Tetraric acids, trivial names, 11 1 Thiamine, 267-307 biosynthesis from 5-amino-l-(P-oribofuranosy1)imidazole.300-303 problems in the study, 268-269 cleavage of bond between pyrimidine and thiazole, 271 -272 mass-spectrometric fragmentation, 274-275 pyramine degradation, 274 structure, 268 synthesis derepression by 5-amino-I -(P-Dribofuranosy1)imidazole 5 ‘-phosphate, 292-293 in spinach chloroplasts, 277 thiazole degradation, 27 1,273 five-carbon chain, pentulose as precursor, 288-29 1 synthesis by E . coli cells, 275-277 thiazole, pyruvate and glucose as five-carbon chain precursors, 282-283
SUBJECT INDEX Thiamine diphosphate, biosynthesis, from thiazole and pyrimidine precursors, 269-271 Thiamine thiazole isolation of carbon C-2,271,273 from pentulose and glycine, 291 Thiazole biosynthesis, in yeasts, 306 cleavage of bond with pyrimidine, 271-272 degradation, 271,273 mass-spectrometric fragmentation, 274 precursors, biosynthesis of thiamine diphosphate, 269-271 Thiazolic metabolites, with probable deoxypentulose origin, 284-287 1-Thioaldose derivatives, thioglycosides preparation, 183 Thioglycolic acid, cleavage of deaminated thiamine, 27 1-272 Thioglycosides, 179-200 anomeric activation/deactivation, 190, 192 block synthesis of oligosaccharides, 191-198 o-glucopyranosyl residues, 195, 198 I-active ganglioside analogue, 193- 194 conversion into other glycosyl donors, 183-184 direct activation, 187 as glycosyl acceptors in oligosaccharide synthesis, 197- 198 glycosylation reactions, “armed-disarmed’ concept, 189- 193 in situ generation of glycosyl halides, 184-185 nomenclature, 135- 136 preparation, 18 I , 183 promoters, 185- 189 stereoselectivity, 189- 190 steric activation-deactivation, 190- 191, 193 1-Thiols, thioglycosides preparation, 183 2,3,4-Tri-O-ethylamylose, structure, 41 2 Triple bonds, unsaturated monosaccharides, 95-96
49 I
Tris(4-bromopheny l)ammoniumy l hexachloroanthirnonate, 187
U Uronic acid definition, 51 nomenclature, 108- 110 polysaccharide derivatives, 165
V Vuloniu, cellulose, 326,329-330 Vitamin B,, biosynthesis, I-deoxy-D-threopentulose in, 287 Vitamin C research of Maurice Stacey, 5-6 studies of polysaccharides of niicroorganisms, 6
W Welan, 389,391 -393,432-434
X Xanthan, 395 X-Ray diffraction analysis, polysaccharides, 314-325 (1 -’3)-P-o-Xylan, 361 (1 +4)-P-~-Xylan, 338-339,407
Y Yeasts pyramine synthesis, 303-306 thiamine, thiazole five-carbon chain, pentulose as precursor, 288-291
I S B N 0-12-007252-1 90051