Purification and characterization of 'Trimarin' a hemorrhagic metalloprotease with factor Xa-like Activity, from Trimeresurus malabaricus snake venom

In the present study, we describe the purification and characterization of a metalloprotease 'trimarin' from Trimeresurus malabaricus snake venom. Trimarin is a single-chain basic protein, with a molecular mass of 29.6 kDa. Trimarin showed proteolytic activity towards casein and fibrinogen, which was irreversibly inhibited by EDTA and 1,10-phenanthroline. The metal ion associated with trimarin was found to be Zn²⁺. Trimarin exhibited pharmacological activities including hemorrhage, myotoxicity, procoagulant and factor Xa-like activities. The hemorrhage and myotoxicity correlated with degradation of extracellular protein components type-IV collagen and fibronectin. Myotoxicity due to muscle tissue necrosis was substantiated with increased serum CK activity. Trimarin showed procoagulant activity with reduced re-calcification time of citrated human plasma. Trimarin shortened the activated partial thromboplastin time (aPTT) and prothrombin time (PT), suggesting its involvement in common pathway of blood coagulation. Trimarin coagulated the citrated human plasma in the absence of CaCl₂, but it was lacking thrombin like activity as it did not clot the purified fibrinogen. Remarkably, the enzyme clotted the factor X deficient human plasma, suggesting that trimarin has factor Xa-like activity. Thus, trimarin may play a key role in the pathophysiological conditions that occur during T. malabaricus envenomation, and may be used as a biological tool to explore many facets of hemostasis.