The carbohydrate moiety of band 3 glycoprotein of human erythrocyte membranes. Structures of lower molecular weight oligosaccharides.

Abstract

Band 3 glycoprotein purified from human blood group A erythrocyte membranes was subjected to hydrazinolysis to release carbohydrate moieties. The neutral oligosaccharide fraction, which constituted more than 85% of the total carbohydrates released, was fractionated by gel chromatography on a column of Sephadex G-50 into two fractions, i.e. higher molecular weight and lower molecular weight fractions. From the lower molecular weight fraction, three oligosaccharides were obtained by chromatographies on columns of Bio-Gel P-4, concanavalin A-Sepharose, and lentil lectin-Sepharose. Their structures were investigated by a combination of compositional analyses, glycosidase treatments, methylation and Smith periodate degradation, and proposed to be: Gal beta 1 - 4GlcNAc beta 1 - 2Man alpha 1 - 6(GlcNAc beta 1 -4) (Gal beta 1 - 4GlcNAc beta 1 - 2Man alpha 1 - 3)Man beta 1 - 4GlcNAc beta 1 - 4(Fuc alpha 1 - 6)GlcNAc, Gal beta 1 - 4GlcNAc beta 1 - 2Man alpha 1 - 6(Gal beta 1 - 4GlcNAc beta 1 - 2Man alpha 1 - 3)Man beta 1 - 4GlcNAc beta 1 - 4(Fuc alpha 1 - 6)GlcNAc, and GlcNAc beta 1 - 2Man alpha 1 - 6(GlcNAc beta 1 - 4) (Glc NAc beta 1 - 2Man alpha 1-3) Man beta 1 - 4GlcNAc beta 1 - 4(+/-Fuc alpha 1 - 6)GlcNAc. It was also demonstrated in this study that most of the higher molecular weight oligosaccharides, whose peripheral structure had previously been reported (Tsuji, T., Irimura, T., and Osawa, T. (1980) Biochem. J. 187, 677-686), also contained the same core hexasaccharide structure, Man alpha 1 - 6(Man alpha 1-3)Man beta 1 - 4GlcNAc beta 1 - 4(Fuc alpha 1-6)GlcNAc, as that of the lower molecular weight oligosaccharides.