Sialic acid dependent polypeptide chain heterogeneity of human fibrinogen demonstrated by two-dimensional electrophoresis.

Human fibrinogen was compared with asialofibrinogen by two-dimensional electrophoresis to evaluate the contribution of sialic acid to the heterogeneity of the gamma- and B beta-polypeptide chains. Reduced fibrinogen showed three major variants for both the gamma- and B beta-chains. In addition two minor gamma-bands with a more acidic isoelectric point than the normal gamma-chains were observed. Electrophoresis in the second dimension (SDS) suggests that these most acidic bands are gamma-chain-variants with a higher molecular weight. In asialofibrinogen only two predominant variants with more alkaline isoelectric points were present in each chain type. It is concluded that enzymatic removal of sialic acid partially reduced the heterogeneity of the gamma- and B beta-polypeptide chains of human fibrinogen, but additional sources producing charge heterogeneity must be sought.