Saccharides, structure

By far the majority of carbohydrate material in nature occurs in the form of polysaccharides. By our definition, polysaccharides include not only those substances composed only of glycosidically linked sugar residues but also molecules that contain polymeric saccharide structures linked via covalent bonds to amino acids, peptides, proteins, lipids, and other structures. 

Comparing the results given in Scheme 41 with those reported for simple OZTs, it can be concluded that /V-acylation of OZTs fused on saccharidic backbones is not affected by the saccharidic structure, the increase in steric hindrance (aldopentose to ketohexose) or the protection of C-l position (OBn, OTBDMS). 

R. Stenutz, I. Carmichael, G. Widmalm, and A. S. Serianni, Hydroxymethyl group conformation in saccharides Structural dependencies of 2JHH, 3JHH, and 1JCH spin-spin coupling constants, J. Org. 

Choose desired tools to view the saccharide structure and save the structure as PDB file. 

Figure 14.1. Construction of query saccharide structure for energy minimization with SWEET. Three-letter codes (IUBMB) for monosaccharides and amino acids are employed to construct oligosaccharide or oligopeptide chains. For monosaccharides, a- and p-anomers are prefixed with a and b, respectively. Pyranose and furanose rings are denoted as p and f, respectively.

Over 70 pyruvated saccharide structures from natural sources are known today, but only a few representative examples are summarized here. The choice has been determined by the synthesis of pyruvated saccharides as discussed in the Sections below. Reference [2] gives a more concise overview of the great structural diversity found among naturally occurring pyruvated oligo- and polysaccharides. 

Such reactions with small alkyl groups are important for saccharide structural analysis. 

Enzyme-lectin histochemistry has many features in common with EIH. Lectins are of non-immune origin but recognize fine differences in complex saccharide structures. Usually lectin specificity is expressed as reactivity to a given monosaccharide, but it has been demonstrated repeatedly (e.g.. Debray et al., 1981) that this is an oversimplification (Section 3.4). It is becoming increasingly clear that cellular differentiation, maturation and neoplastic transformation are associated with changes of carbohydrate composition of the cell membrane (Ponder, 1983). 

The contribution provided by K. Dill and R. D. Carter treats a specialized aspect of metal ion-carbohydrate interaction, devoted to the use of C-n.m.r. spectroscopy with Gd and Mn in particular as shift rea nts and relaxation probes to study the behavior of biological carbohydrates that normally interact with Ca and Mg. A newer technique that will certainly take its place as a standard tool in pols saccharide structural analy is the selective depolymerization by anhydrous hydrogen fluoride, here surveyed by Yu. A. Knirel and E. V. Vinogradov (Moscow, U.S.S.R.) and A. J. Mort (Stillwater, OK). 

The critical role of carbohydrate recognition in cellular functioning has impelled aggressive research directed toward the understanding and control of the intermolecular processes involved in carbohydrate metabolism and signaling. Modified saccharide structures incorporating /V-thiocarbonyl... 

See also Saccharides, Structural Polysaccharides, Oligosaccharides, Monosaccharide Nomenclature, Biosynthesis of Polysaccharides (from Chapter 16), Biosynthesis of Other Polysaccharides (from Chapter 16), Biosynthesis of Amino Sugars (from Chapter 16), Biosynthesis of... 

At 1604 and 1404 cm , two intense peaks corresponding to carboxyl group (COO- asymmetric and symmetric stretching) were identified Other peaks were identified at 1317, 1124, and 1087 cm , characteristic to oligo-sugars whereas the intense peak at 1027 and 945 cm is specific to the C-O bonds of the saccharide structure and indicate the presence of guluronic and mannu-ronic acids, respectively. ... 

---