Study on the thrombin-like enzyme preferentially releasing fibrinopeptide B from the snake venom of Agkistrodon halys Pallas.

Three components with arginine esterase activities were found in the venom of the Chinese pit viper (Agkistrodon halys Pallas). They were identified as bradykinin releasing, thrombin-like and fibrinogenolytic enzymes respectively. The thrombin-like enzyme of A. halys Pallas was purified to a homogeneous state. It was a glycoprotein with molecular weight of about 43,000. Though this enzyme displayed a higher esterase activity on BAEE than trypsin and human thrombin, it showed very weak clotting ability on fibrinogen. The kinetic analysis of the release of fibrinopeptides A (FPA) and B (FPB) showed that the action mode of this enzyme on fibrinogen was just opposite to that of mammalian thrombin. FPB was first released, followed by FPA after a long lag period.