Carbohydrates and their

The mass spectra of free carbohydrates and their glycosides, obtained by ionization upon electron impact, are limited in their usefulness for structural studies. Peaks corresponding to molecular ions are generally not observed due to extensive fragmentation to ions of low m/e (4,9,11, 24, 26). In contrast, positive ions produced by field ionization do not give fragment spectra as characteristic as do those produced by electron impact, but the molecular ion peaks are intense, often the most intense in the spectra (3). 

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. 

B. Interactions of [organotinllV)]" with carbohydrates and their derivatives... 

R. Goldberg and J. Tewari, Thermodynamic and transport properties of carbohydrates and their monophosphates The pentoses and hexoses, J. Phys. Chem. Ref. Data, 18 (1989) 809-822. 

Although carbohydrates and their corresponding conjugated glycoforms have long been regarded as only space-filling matrices or post-transcriptional accessory... 

Formation of the Intermediate Compound between Carbohydrates and Their Specific Enzymes. 76... 

While the broad mission of the National Bureau of Standards was concerned with standard reference materials, Dr. Isbell centered the work of his laboratory on his long interest in the carbohydrates and on the use of physical methods in their characterization. Infrared spectroscopy had shown promise in providing structural and conformational information on carbohydrates and their derivatives, and Isbell invited Tipson to conduct detailed infrared studies on the extensive collection of carbohydrate samples maintained by Isbell. The series of publications that rapidly resulted furnished a basis for assigning conformations to pyranoid sugars and their derivatives. Although this work was later to be overshadowed by application of the much more powerful technique of nuclear magnetic resonance spectroscopy, the Isbell— Tipson work helped to define the molecular shapes involved and the terminology required for their description. 

Gunning, Y.M.. Parker. R.. Ring. S.G.. Rigby. N.M.. Wegg, B., and Blake, A. Phase behavior and component partitioning in low water content amorphous carbohydrates and their potential impact on encapsulation of flavors, J. Agric. Food Chem., 48(2) 395-399, 2000. 

Molecular Dynamics Simulations of Carbohydrates and Their Solvation... 

The enzymatic approach to the synthesis of carbohydrates and their precursors is practical for certain types of sugars. The next stage of our investigation will be to focus on the modification of these readily available sugars to agents of interest. Improvement of enzyme properties for synthetic application is also of interest. 

B. Gyurcsik and L. Nagy, Metal complexes of carbohydrates and their derivatives Coordination equilibrium and structure, Coord. Chem. Rev., 203 (2000) 81-149. 

Abstract Polyfunctionality of carbohydrates and their low solubility in conventional organic solvents make rather complex their conversion to higher value added chemicals. Therefore, innovative processes are now strongly needed in order to increase the selectivity of these reactions. Here, we report an overview of the different heterogeneously-catalyzed processes described in the literature. In particular, hydrolysis, dehydration, oxidation, esterification, and etherification of carbohydrates are presented. We shall discuss the main structural parameters that need to be controlled and that permit the conversion of carbohydrates to bioproducts with good selectivity. The conversion of monosaccharides and disaccharides over solid catalysts, as well as recent advances in the heterogeneously-catalyzed conversion of cellulose, will be presented. 

Proteoglycans are widely distributed throughout the body, being most abundant in connective tissue, where they may contribute up to 30% of that tissue s dry weight. They consist of a polypeptide backbone to which heteropolysaccharide chains are attached. However, unlike glycoproteins, proteolycans consist of up to, or in excess of, 95% carbohydrate and their properties resemble those of polysaccharides more than those of proteins. 

Gorelik E, Galili U, Raz A. On the role of cell surface carbohydrates and their binding proteins (lectins) in tumor metastasis. Cancer Metast Rev 2001 20 245-277. 

Despite the results obtained by Jones and coworkers,409 interest in the separation of carbohydrate acetates lapsed for several years. This was partly due to the complexity of the liquid phase used by these investigators, and partly because the acetates of certain common alditols could not be separated on the then-available column-packings. In addition, it was at just about this time that Sweeley and coworkers5 introduced the use of trimethylsilylation, and demonstrated that a wide range of carbohydrates and their derivatives could be separated by this technique. 

See also T. D. Inch, Formation of convenient chiral intermediates from carbohydrates and their use in synthesis, Tetrahedron 40 3161 (1984). 

For reviews see (a) R. J. Fenier and S. Middleton, The conversion of carbohydrates into functionalized cyclopentanes and cyclohexanes, Chem. Rev. 95 2779 (1993) (b) K. J. Hale, Monosaccharides Use in asymmetric synthesis of natural products, Rodd s Chemistry of Carbon Compounds. Second Supplement to the 2nd ed. (M. Sainsbury, ed.), Elsevier, Amsterdam, 1993, Vol. 1E/F/G, pp. 315-435 (c) T. D. Inch, Formation of convenient chiral intermediates from carbohydrates and their use in synthesis, Tetrahedron 40 3161 (1984) (d) S. Hanessian, Total Synthesis of Natural Products The Chiron Approach Pergamon, New York, 1983. 

When the main fundamental work in one field was done, he moved on to a new one. Only the carbohydrates and their reciprocal relations to the enzymes, as well as the resulting stereochemical problems, fascinated him even to his last days. The greater part of Emil Fischer s enormous work was directed to entire groups of natural compounds, which he treated fundamentally and, for his time, most thoroughly. 

The study of such techniques as F.t.-i.r., computerized laser-Raman, or n.c.a., however great their degree of sophistication, should have practical utility for carbohydrate chemists and biochemists. That is why, amid the current problems elucidated by the interpretation of the vibrational spectra of carbohydrates and their derivatives, a section has been reserved for discussion of structure-properties relationships. 

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