Comparative Studies on the Structures of the Carbohydrate Moieties of Human Fibrinogen and Abnormal Fibrinogen Nagoya1

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Abstract
Human fibrinogen contains four asparagine-linked sugar chains in one molecule. All Bβ and γ subunits obtained from both normal fibrinogen and abnormal fibrinogen Nagoya contain 1 mol each of an asparagine-linked sugar chain. The sugar chains were quantitatively liberated as radioactive oligosaccharides from the poly-peptide portion by hydrazinolysis followed by N -acetylation and NaB 3 H 4 , reduction. By the combination of sequential exoglycosidase digestion and methylation analysis, the structures of the sugar chains of human fibrinogen were elucidated to be Neu-Aca2 → 6Galβ1 → 4GlcNAcβ1 → 2Manα1 → 6(NeuAcα2 → 6Ga1β1 → 4G1cNAcβ1 → 2Manα1 → 3)Manβ1 → 4GlcNAcβ1 → 4GlcNAc and Galβ1 → 4GlcNAcβ1 → 2Manα1 → 6(NeuAcα2 → 6Galβ1 → 4GlcNAcβ1 → 2Manα1 → 3)Manβ → 4GlcNAcβ1 → 4GlcNAc. Neither quantitative nor qualitative differences were found between the sugar chain moieties of normal fibrinogen and fibrinogen Nagoya, indicating that the molecular basis of the abnormality in the latter may reside in its polypeptide moieties.