Oligosaccharides methylation analysis

Xylans as true homopolymers occur in seaweeds of the Palmariales and Nemaliales, however, their backbone consists of Xylp residues linked by -(1 3) (Type X3, Fig. la) or mixed -(1 3, 1 -> 4)-glycosidic linkages (Type Xmy Fig. lb). They are assumed mainly to have a structural function in the cell-wall architecture, but a reserve function cannot be ruled out [4]. From the microfibrils of green algae (Siphonales) such as Caulerpa and Bryop-sis sp., X3 was isolated and the structure confirmed by methylation analysis, C-NMR spectroscopy [7], as well as by mass spectrometry of enzymically released linear oligosaccharides up to a degree of polymerization (DP) of... 

A detailed study of the 0-linked oligosaccharides present on the surface of normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells has been completed. Structures were elucidated by f.a.b.-m.s. after permethylation, and methylation analysis before and after specific exo-glycosidase treatments. Some of the components were shown by f.a.b.-m.s. to be poly(N-acetyllactosaminyl) oligosaccharides, for example, 29. 

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. 

Methylation analysis Permethylation of intact oligosaccharides Hydrolysis of glycosidic linkages Reduction to monosaccharide alditols Acetylation of free hydroxyl groups previously involved in link-... 

The structure of the (l- 2)-a-D-mannopyranan has been confirmed by methylation analysis, and its interaction with concanavalin A has been tested. Concanavalin A forms a weak complex with this oligosaccharide, and this is precipitated. Two molecules of concanavalin A must, therefore, be able to link to a sequence of two, or three, (1— 2)-a-D-mannopyranosyl residues. The polymer thus gives some insight into the steric requirements, and the size of the active site, of this lectin.120... 

Terminal 3,6-dideoxyhexoses that occur in lipopolysaccharides from Salmonella and Yersinia (Pasteurella) species7 could be hydrolyzed off with a high degree of selectivity. They may, therefore, be located by methylation analysis of the original lipopolysaccharide and of a partially hydrolyzed sample. Thus, for the Salmonella typhi-murium 395 MS lipopolysaccharide, composed18 of oligosaccharide... 

The structures of oligosaccharides and polysaccharides are usually determined by a combination of methods specific enzymatic hydrolysis to determine stereochemistry and produce smaller fragments for further analysis methylation analysis to locate glycosidic bonds and stepwise degradation to determine sequence and configuration of anomeric carbons. 

In conjunction with methylation analysis and the known specificity for the oligosaccharide chain of a particular endo-/V-acetyl-/3-D-glucos-aminidase (D), a structure was proposed for the desulfated material, leading to 54 for the structure of the desulfated polymer. The same structure has... 

The extracellular polysaccharides of Rhizobium meliloti 201 have been examined by using enzymic degradation and chemical procedures.314 A mixture of polysaccharides produced by the bacterium, when incubated with a bacterial enzyme that hydrolyzed one of these, gave oligosaccharides that could be separated by DEAE-cellulose chromatography. The major fraction was a pentasaccharide, for which methylation analysis and Smith... 

Ten sialic-acid-containing oligosaccharides and four neutral oligosaccharides have been purified from the major glycoprotein fraction of hog, submaxillary-gland mucin. H-N.m.r. spectroscopy at 360 MHz, in combination with methylation analysis and mass spectrometry, allowed the determination of their structures, which are partial structures of a pentasaccharide (see Fig. 42) having blood-group A activity.221... 

The complete structures of the oligosaccharides from these antigens were elucidated by using FAB-MS, NMR, acetolysis, and methylation analysis. Further key experiments performed by Hunter et al.st involved partial acid hydrolyses of... 

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