The carbohydrate moiety of human platelet glycocalicin: the structures of the major Asn-linked sugar chains.

Glycocalicin, a predominant glycoprotein on the human platelet surface, has been purified from a platelet suspension by means of sonication, ammonium sulfate precipitation and acid treatment followed by chromatography on columns of wheat germ agglutinin-Sepharose and Mono Q. Asparagine-linked (N-linked) oligosaccharides were released by hydrazinolysis, and then N-acetylated and reduced with NaBH4 or NaB3H4. The released carbohydrate chains were found to be of the complex-type from their interaction with immobilized lectin columns. The structures of the two major oligosaccharide-alditols separated by ion-exchange chromatography on a Mono Q column were investigated by means of methylation analysis, glycosidase digestion, and Smith periodate degradation, and they were assigned as typical di- and trisialylated complex-type oligosaccharide-alditols with two and three peripheral chains consisting of Gal-GlcNAc sequences, respectively.