Adsorption of purified thrombin or antithrombin III for two insoluble anticoagulant polystyrene derivatives: II. Competition with the other plasma proteins.

In the preceding paper, we described results concerning the adsorption of purified thrombin and antithrombin III on two insoluble anticoagulant polystyrene derivatives. We now report similar results obtained in a plasma system. In each case, the purified protein was mixed with fresh platelet poor plasma in order to maintain the same concentrations of all the other plasma proteins. The thrombin molecule was modified by alkyl phosphorylation of the active serine site prior to mixing with plasma. The adsorption of antithrombin was found to be reduced 8 to 9 times when the protein solution was substituted by diluted plasma. In contrast, the thrombin adsorption only depends on the substituents bound on the polymeric chain. These results are supported by those of the study of the competition between purified antithrombin and albumin.