Does fibrinogen contain populations with different degree of sialylation?

The reactivity of the galactose specific lectin from Ricinus communis seeds, ricin, towards the fractions of fibrinogen separated by DEAE-cellulose chromatography and their isolated glycopeptides was studied. Ricin is known to differentiate oligosaccharide chains with different degree of sialylation. The results indicated that the fractionation of fibrinogen is not correlated with a different degree of sialylation of its oligosaccharide chains. The higher sialic acid content of the most acidic fraction correlates with a higher neutral sugar content due to the presence of highly glycosylated contaminants. The possibility that the heterogeneity in the degree of sialylation is only of intramolecular nature is discussed.