Serine protein with fibrinolytic and fibrinogenolytic activities. Degrades Bbeta-chain (FGB) of fibrinogen first and then the Aalpha-chain (FGA). Gamma-chain (FGG) are also digested on prolonged incubation. In vitro, it cleaves high molecular weight (HMW) kininogen (KNG) releasing bradykinin that promotes vasodilation. In vitro and in vivo, it cleaves angiotensin-2 (AGT). This explains the reduction of blood pressure in hypertensive rats. Has also antithrombotic effects on thrombosis animal models. Inhibited by PMSF. Optimum pH is 8.0. Optimum temperature is 65 degrees Celsius. Monomer. Expressed by the venom gland. Harobin contains three additional Cys residues than other snake venom serine proteases, suggesting an additional disulfide bond. In addition, it is more stable than other snake 6-disulfide-bond serine proteases, since it is less sensitive to DTT. Has no fibrinogen clotting ability. Is not a plasminogen activator. Does not affect angiotensin-converting enzyme (ACE). In vivo, does not show hemorrhagic activity in mice (PubMed:17544404). Belongs to the peptidase S1 family. Snake venom subfamily.