Thrombin and prothrombin (F2) inhibitor. The IC(50) of thrombin-induced platelet aggregation and fibrinocoagulation is 62 and 35 nM, respectively. Its inhibitory activity is at least 10-fold lower than that observed for other thrombin inhibitors. Heterodimer of subunits alpha and beta; disulfide-linked. Expressed by the venom gland. Belongs to the snaclec family.