[Chemical properties of plasma fibrinogens and fibrins from normal and cobalt-treated rabbits].

The sulfitolysis products of fibrinogens from normal and cobalt-treated rabbits (5 mg Co2+/kg b.w.) were resolved by ion exchange chromatography on CM-cellulose columns. The elution patterns of both fibrinogens showed a distinct heterogeneity of gamma-chains. Furthermore, a gamma-chain derivative from cobalt fibrinogen could be distinguished electrophoretically from the corresponding one of normal fibrinogen because of its reduced electrophoretic mobility. Normal and cobalt fibrinogen did not differ from each other in their N-terminal (Val2 Ala2 Tyr2) and C-terminal (Pro1-2 Val4-5) amino acid compositions related to a subunit structure of A alpha 2 B beta 2 gamma 2, and their carbohydrate contents - neutral hexoses 1,21% (1,26%), N-acetyl hexosamines 1,16% (1,05%), N-acetyl neuraminic acid 1,19% (1, 13%), values for cobalt fibrinogen in parentheses. The main amounts of carbohydrates are bound to gamma- and B beta-chains, The BrCn cleavage products from cobalt fibrinogen and its gamma- and B beta-chains showed other electrophoretic properties than the corresponding derivatives from normal fibrinogen. But BrCN split products of A alpha-chains of both fibrinogens were electrophoretically very similar. Spectrographic investigations of the S-sulfoderivates demonstrated a diminution of the absorption maximum near 282mn of gamma and B beta derivatives of cobalt fibrinogen. A alpha-chains of both fibrinogens were not different from each other. Using autoradiography the highest 58Co binding could be found in the gamma-chain with a reduced electrophoretic migration velocity, whereas B beta-and gamma-chains with unchanged electrophoretic mobility bound only small amounts. A alpha-chains of cobalt fibrinogens were apparently not loaded with 58Co. gamma-chain and alpha-chain cross-links could be observed in normal fibrins stabilized by factor XII, however, in cobalt fibrins a gamma-dimer formation was demonstrable without participation of gamma-chains with reduced electrophoretic mobility. A distinct alpha-chain cross-link could not be demonstrated either. From these and other investigations on molecular weights of both fibrinogens it was assumed that earlier observed changes of physicochemical properties and biological behaviour of cobalt fibrinogen might result from a complex binding of cobalt ions on specific structures of the fibrinogen molecule.