[Importance of the sialic acid moiety for the heterogeneity in human fibrinogen].

To determine whether the observed heterogeneity of gamma- and B beta-polypeptide chains of human fibrinogen (2 and 1 sialic acid residue per chain) is due to differences in sialic acid content, fibrinogen was desialatgen was compared with normal fibrinogen. The gamma-chain heterogeneity observed in normal fibrinogen was absent in asialofibrinogen, whereas the B beta-chain heterogeneity appeared to be unaffected. Although the variants were indistinguishable on SDS-PAGE, isoelectric focusing in the presence of urea demonstrated heterogeneities of both gamma- and B beta-cahins even in asialofibrinogen. However, fewer bands were recognized in asialofibrinogen. The difference in sialic acid content of the gamma- and B beta-chain variants of human fibrinogen therefore explains on part of the polypeptide chain heterogeneity.