A direct-acting fibrinolytic enzyme from the venom of Agkistrodon contortrix contortrix: effects on various components of the human blood coagulation and fibrinolysis systems.

A direct acting fibrinolytic enzyme (fibrolase) has been isolated from venom of the southern copperhead snake (Agkistrodon contortrix contortrix). Time-course experiments established that the venom enzyme cleaves primarily the A alpha-chain of human fibrinogen and fibrin between the Lys-413 and Leu-414 position. The B beta-chain is cleaved more slowly, while the gamma-chain is minimally affected. The cleavage pattern of fibrinogen and fibrin clearly varies from plasmin cleavage of the same molecules. The enzyme does not activate plasminogen or protein c and it is thus different from "Protac", a protein c activator isolated from the same venom.