Structures of carbohydrate chains of glycoprotein isolated from goat submaxillary mucin

Abstract

One of the glycoprotein fractions isolated from goat submaxillarymucin contains l-fucose, d-galactose, d-glucose, d-mannose, N- acetyl- d- galactosamine, N- acetyl- d- glucosamine and N-acetylneuraminic acid. The material was subjected to the action of proteolytic enzymes as well as NaBH 4 to yield four types of carbohydrate chain. The largest chain is an octasaccharide. In the glycopeptides isolated, threonine and serine were obtained in major proportions when compared to other amino acids, suggesting that the carbohydrate moiety is linked to the polypeptide chain at serine or threonine or both residues. The positions of linkages between various sugar units were studied by methylation analysis and periodate oxidation studies. The sequence of sugar residues and their anomeric configurations in the earbohydrate chain were determined by applying specific glycosidases to the glycopeptides. From the results of these studies, a structure was assigned to the carbohydrate chain of the goat submaxillary glycoprotein (mucin).