We present evidence that the serine protease found in bumblebee (Bombus terrestris) venom exhibits fibrin(ogen)olytic activity. Compared to honeybee (Apis mellifera) venom, bumblebee venom contains a higher content of serine protease, which is one of its major components. Venom serine proteases from bumblebees did not cross-react with antibodies against the honeybee venom serine protease. We provide functional evidence indicating that B. terrestris venom serine protease (Bt-VSP) acts as a fibrin(ogen)olytic enzyme. Bt-VSP activates prothrombin and directly degrades fibrinogen into fibrin degradation products. However, Bt-VSP is not a plasminogen activator, and its fibrinolytic activity is less than that of plasmin. Taken together, our results define roles for Bt-VSP as a prothrombin activator, a thrombin-like protease, and a plasmin-like protease, providing significant support for thepotential use of bumblebee venom serine protease as a clinical agent.

• Yuling Qiu(College of Natural Resources and Life Science, Dong-A University)
• Hyung Joo Yoon(Department of Agricultural Biology, National Academy of Agricultural Science)
• Byung Rae Jin(College of Natural Resources and Life Science, Dong-A University)