Mechanism of the anticoagulant, Cerastase F-4, isolated from Cerastes cerastes (Egyptian sand viper) venom.

An anticoagulant enzyme, Cerastase F-4, from the venom of Cerastes cerastes was purified to homogeneity and was characterized (1). In the present report the mode of its fibrinogenolytic and fibrinolytic actions, and its effects on some other blood coagulation factors are described. Cerastes F-4 was shown to readily hydrolyze the alpha A chain of fibrinogen followed by the hydrolysis of the beta B chain. The gamma-chain was relatively resistant to hydrolysis. It also degrades the three chains of fibrin at different rates. The degradation products of the two substrates shown on SDS-polyacrylamide gel were quite different from those produced by plasmin, indicating different sites of cleavage by the enzyme. Using specific chromogenic substrates, Cerastase F-4 seems not to show thrombin-like, plasmin-like, kallikrein-like, antithrombin, or antiplasmin actions. Also, it does not activate prothrombin or plasminogen but degrades both of them slowly. It is concluded that the anticoagulation property of the purified enzyme, Cerastase F-4, is due to its destruction of fibrinogen.