Glycoconjugates methanolysis

Chaplin used methanolysis for the analysis of carbohydrates in glycoproteins. His method was a variation of the foregoing procedures, with an improvement of using tert-hvAyX alcohol to remove hydrogen chloride by coevaporation, instead of prolonged trituration with silver carbonate. His method is useful for samples containing uronic acids and lipids. Mononen studied methanolysis, followed by deamination and reduction with borohydride, for determination of the monosaccharide constituents of glycoconjugates. This method was applied to a lipid-free, protein fraction of rat brain. 

In the methanolysis procedure, as used for the standard quantitative monosaccharide GLC analysis of glycoconjugates [240,241], 1 M methanolic HCl (24 h, 85 C) is applied. However, under these conditions released sialic acids are completely de-Af,0-acylated, which makes this approach unsuitable for the characterization of different types of sialic acid. It is, however, a reliable approach for the determination of the total amount of a mixture of (0-acetylated) A-acylneuraminic acids. When using a milder methanolysis procedure (0.05 M methanolic HCl, 1 h, 80 C) the de-iV-acylation but not the de-O-acylation is strongly reduced [242]. 

Zanetta J-E, Timmerman P, and Leroy Y (1999b) Determination of constituents of sulphated proteoglycans, using a methanolysis ptocedute and gas chromatogtap-hy/mass specttometry of heptafluotobutyrate derivatives. Glycoconjugate Journal 16 617-627. 

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