Oligosaccharides defined

Physical Properties. Oligosaccharide antibiotics are colodess soHds, which are often crystalline and have defined melting poiats and optical rotations, [cc] (see Tables 1 and 2). They have a characteristic uv spectmm resulting from the phenoHc ester residue, 285 nm (s ca 22), which shifts... 

Carb-38. Use of symbols for defining oligosaccharide structures 2-Carb-38.1. General considerations... 

Another reason is that xylo-oligosaccharides of defined structure are very important substrates that serve as model compounds for the optimization of hydrolytic processes and in enzymic assays. The enormous development... 

Many studies have been conducted in an attempt to define the precise roles oligosaccharide chains play in the functions of glycoproteins. Table 47-2 summarizes results from such studies. Some of the functions listed... 

It is usually desirable to define molecular weights by analyzing underivatized samples, because chemically labile functional groups will then be observed. Unfortunately, underivatized oligosaccharides often give ambiguous sequence-data. The reasons for this may be deduced from a... 

F.a.b.-m.s. has contributed to a detailed analysis of the high-mannose carbohydrate chains of prostaglandin endoperoxide synthase from sheep. Oligosaccharides released by hydrazinolysis were analyzed after N-re-acetylation and reduction. The f.a.b. data defined the compositions of the oligosaccharides, and showed that hydrazinolysis had effected a partial fission of the chitobiose core. 

In a study completed during the early development of f.a.b.-m.s., both f.d. and f.a.b. were used to characterize 101 fractions containing neutral oligosaccharides isolated from human milk. Samples were examined as their peracetylated alditols. In subsequent work, the structures of two minor acidic oligosaccharides from human milk were investigated. The per-methylated derivatives were analyzed by f.a.b.-m.s., and their compositions and sequences were defined by the f.a.b. data. Methylation analysis and partial formolysis were the other principal methods used. 

M. Jahn, D. Stoll, R. A. Warren, L. Szabo, P. Singh, H. J. Gilbert, V. M. Ducros, G. J. Davies, and S. G. Withers, Expansion of the glycosynthase repertoire to produce defined manno-oligosaccharides, Chem. Commun. (Camb.), 12 (2003) 1327-1329. 

J. P. Thompson and C.-L. Schengrund, Oligosaccharide-derivatized dendrimers Defined multivalent inhibitors of the adherence of the cholera toxin B subunit and the heat labile enterotoxin of E. coli to GM1, Glycoconjug. J., 14 (1997) 837-845. 

The trichloroacetimidate method has also found wide applications in the synthesis of various complex oligosaccharides. In the course of the development of chemically defined glycoconjugate vaccines against shigellosis, a decasaccharide, corresponding to two consecutive repeating units of the O-specifk polysaccharide of Shigella... 

The synthesis of libraries of structurally defined compounds can potentially be achieved either by split-mix synthesis or by parallel synthesis of individual compounds. The synthesis requires a reliable methodology of oligosaccharide synthesis, where stereochemistry and regioselectivity have to be achieved unlike other library approaches. Development of synthetic methodologies that can provide access to any oligosaccharide structure is underway. 

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