The structure of the O-glycosidic oligosaccharide chains of the major Zajdela hepatoma ascites-cell-membrane glycoprotein.

Abstract

Glycoprotein MII2, the major cell surface glycoprotein (molecular mass 110 kDa) of Zajdela hepatoma ascites cells, contains about 25 O-glycosidic oligosaccharide chains per molecule. They were released as oligosaccharide-alditols by alkaline borohydride treatment of MII2, and purified by gel filtration on Bio-Gel P-6 followed by high-voltage paper electrophoresis. Four oligosaccharide-alditol fractions (A-D) were obtained in relative yields of 8:6:3:3. The structure of the components of fractions A-C was determined by 500-MHz 1H-NMR spectroscopy in combination with sugar composition analysis, to be as follows. (A) NeuAc alpha(2----3)Gal beta(1----3)[NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----6)]GalNAc-ol; (B1) NeuAc alpha(2----3)Gal beta(1----3)[Gal beta(1----4)GlcNAc beta(1----6)]GalNAc-ol; (B2) Gal beta(1----3)[NeuAc alpha(2----3)Gal beta(1----4)GlcNAc beta(1----6)]GalNAc-ol; (C) NeuAc alpha(2----3)Gal beta(1----3)GalNAc-ol. On the basis of sugar composition and characteristics on Bio-Gel P-6 filtration, paper electrophoresis and thin-layer chromatography, the structure of the carbohydrate component of fraction D is proposed to be as follows. (D) NeuAc alpha(2----3)Gal beta(1----3)[NeuAc alpha(2----6)]GalNAc-ol