DEGRADATION OF M AND N BLOOD GROUP GLYCOPROTEINS AND GLYCOPEPTIDES WITH ALKALINE BOROHYDRIDE

The sialic acid‐free M and N substances and glycopeptides from their pronase digest were treated with alkaline borohydride and products of degradation were fractionated. Galactose and N‐acetylgalactosamine were split off during the degradation in the form of disaccharide: galactosyl‐N‐acetylgalactosaminitol, and it was accompanied by the release of amino acid components. The conclusion has been drawn that a part of carbohydrate moiety of M and N substances represents trisaccharides: N‐acetylneuraminyl–galactosyl–N‐acetylgalactosamine, linked to serine and threonine residues in the peptide chain by an alkali‐labile O‐glycosidic bond. The other type of oligosaccharides present in M and N substances is linked to peptide chain by an alkali‐stabile bond and includes mannose, fucose, N‐acetylglucosamine, the rest of sialic acid and galactose. The degraded M′ and N′ glycoproteins (M and N glycoproteins free of N‐acetylneuraminic acid) did not inhibit the hemagglutination by Vicia graminea phytoagglutinins. The degraded native M and N substances were inactive towards both anti‐M and anti‐N rabbit immune sera, and anti‐N phytoagglutinins from V. graminea, but they were still as good inhibitors of viral hemagglutination as untreated substances. Copyright © 1969, Wiley Blackwell. All rights reserved