Comparison of the inhibition of thrombin by three plasma protease inhibitors.

摘要: Human alpha-thrombin is inhibited by the circulating protease inhibitors alpha1-antitrypsin, antithrombin III, and alpha2-macroglobulin. Kinetic analyses of inhibitor thrombin interactions were carried out utilizing either fibrinogen or synthetic substrate Bz-Phe-Val-Arg-p-nitroanilide as substrates to determine residual activity. These studies demonstrated that inhibition alpha2-macroglobulin followed second-order kinetics. The rate constants for are 6.51 +/- 0.38 x 10(3), 3.36 0.34 10(5), 2.93 0.02 10(4) M-1 min-1, respectively. Comparison normal plasma levels three demonstrates that, under in vitro conditions utilized, III five times one-third effective alpha1-antitrypsin thrombin.