Mannose methylation analysis

Levene and Sobotka repeated Dale s experiments using crystalline acetylmannosyl bromide as the starting material. Their product was identical with the y-form of Dale s new methyl mannoside acetates. Deacetylation by alkali led to a dry, hygroscopic mass, which gave the correct analysis for D-mannose methyl 1,2-orthoacetate. From the crystalline acetylmannosyl bromide, on treatment with ethyl alcohol and silver carbonate, they prepared the analogous ethyl orthoacetate (Illb) with m. p. 81-82° and C ]d —28°. On saponification, it behaved in a manner analogous to the methyl derivative prepared from the same source. For the deacetylation of the triacetyl-n-mannose methyl 1,2-orthoacetate, Bott, Haworth and Hirst employed 0.5 N sodium hydroxide in ethanol at 0°. 

Autohydrolysis of H. holstii Q-phosphonomannan (mannose 5) liberates a pentasaccharide monophosphate of the apparent structure given in Figure 3. The structure of the dephosphorylated oligosaccharide was deduced from a methylation analysis (59) and accords with earlier Smith degradations of the intact biopolymer... 

P-mannans (47). The most extensive structural investigations were carried out on the mannan from the best producer, R. glutinis. An alternating arrangement of 3-(1 3)- and 3-(1 4)-linked residues was deduced from methylation analysis and characterization of di-and trisaccharides liberated by partial acid hydrolysis. Crystalline 4-0-3-g-mannopyranosyl-g-mannose was isolated in 67% yield. 

Studies of the chemical composition and biology of the lipopolysaccharide from Anacystis nidulans have been reported. The glycan component of this lipopolysaccharide is composed mainly of residues of o-mannose and small proportions of 3- and 4-0-methyl-D-mannose, D-galactose, D-glucose, L-fucose, 2-amino-2-deoxy-D-glucose, 2-amino-2-deoxy-D-mannose, and 3-deoxy-2-octulo-sonic acid. Methylation analysis and oxidation of the D-mannan chain with periodate revealed the presence of (1 3)- and (1 4)-linkages in the ratio 3 1. 

Each of three globosides from spermatozoa of the fresh-water bivalve Hyriopsis schlegelii contains D-mannose instead of D-galactose in the carbohydrate portion of the molecule. The structure (17) was deduced for one of them on the basis of methylation analysis, enzymic hydrolysis, and oxidation with chromium trioxide. 

A glycopeptide (mol. wt. 1.3 x 10 ), containing L-fucose, D-mannose, D-glucose, and asparagine, has been isolated from the products of proteolysis of the lima bean lectin Phaseolus lunatus). Methylation analysis. Smith degradation, and subsequent degradation by specific glycosidases has resulted in the tentative proposal of a structure (5). 

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