Methylation-gas Chromatography-mass Spectrometry Research Articles

Major oligosaccharides in the glycoprotein of Friend murine leukemia virus: structure elucidation by one- and two-dimensional proton nuclear magnetic resonance and methylation analysis.

The highly microheterogeneous, N-glycosidically linked oligosaccharides in the glycoproteins of Friend murine leukemia virus (as produced by Eveline cells) were liberated with endo-beta-N-acetylglucosaminidase H and by alkaline hydrolysis. They were fractionated (as desialylated oligosaccharitols) by gel filtration and by concanavalin A affinity chromatography, and the major fractions were analyzed by methylation-gas chromatography-mass spectrometry, by digestion with exoglycosidases, and, especially, by one- and two-dimensional proton nuclear magnetic resonance spectroscopy. Guidelines for qualitative and quantitative analysis of complex oligosaccharide mixtures by NMR were worked out and the results compared with those obtained by methylation analysis. It was found that these major fractions consist of bi-, tri-, and tetraantennary oligosaccharitols of the "complex" type (comprising a minority of species with N-acetyllactosamine repeating units), which are, in part, substituted by nonreducing terminal Gal alpha (1----3) and/or bisecting GlcNAc beta (1----4) residues.

Structural analysis of mannans from Candida albicans serotypes A and B and from Torulopsis glabrata by methylation gas chromatography mass spectrometry and exo-alpha-mannanase.

Mannans of Candida albicans serotypes A and B and of Torulopsis glabrata were subjected to methylation analysis and the resulting monosaccharides were converted to the peracetylaldononitrile derivatives and subsequently analyzed by gas chromatography mass spectrometry. Serotype A differed from B in having more 1 leads to 2 linked mannosyl residues (46.2 vs 37.1 mol%) indicating longer oligomannosyl sidechains; mannosyl branch points linked through C-1, C-3 and C-6 were detected for the first time in C. albicans mannans and were more abundant in serotype B (9.2 vs 5.3 mol%). T. glabrata mannan differed from that of C. albicans in having virtually no (1.6 mol%) unsubstituted sugars in the linear backbone and less 1 leads to 2 linked mannosyl residues (33.1 mol%) interpreted as shorter oligomannosyl sidechains. Model building of a repeating unit for the outer chain region of these mannans was prevented by the large amount of nonreducing terminal mannosyl residues, 23.0 mol% for C. albicans A, that probably arise from the inner core region. These mannans were exposed to exo-alpha-mannanase and the percentage of digestion, measured as reducing sugar released, was 33.5% for C. albicans B; 27.4% for T. glabrata, and C. albicans A was refractory (5.4% digested).