Studies on the structures of the carbohydrate moiety of human prothrombin

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: (sequence in text).