Studies on the Structures of the Carbohydrate Moiety of Human Prothrombin1

Abstract

Human prothrombin contains three asparagine-linked sugar chains in one molecule. The sugar chains were quantitatively liberated as radioactive oligosaccharides from the polypeptide moiety by hydrazinolysis followed by N-acetylation and NaB³H⁴ reduction. All of the oligosaccharides contain N-acetylneuraminic acid. The neutral oligosaccharides obtained from all acidic oligosaccharides by sialidase digestion are identical. By the combination of sequential exoglycosidase digestion and methylation analysis, the structures of the asparagine-linked sugar chains of human prothrombin were confirmed to be as follows: NeuAcα2→6Galβ1→4GlcNAcβ1→2Manα1→ 6(NeuAcα2→6Galβ1→4GlcNAcβ1→2Manα1→3)Manβ1→4GlcNAcβ1→4GlcNAc, NeuAcα2→6Galβ1→4GlcNAcβ1→2Manα1→6(Galβ1→4GlcNAcβ1→2Manα1→3)Manβ1→4GlcNAcβ1→and Galβ1→4GlcNAcβ1→4GlcNAcβ1→2Manaα1→6)NeuAcα2→6Galβ1→4GlcNAcβ1→;2Manα1→3)Manβ1→4GlcNAc.