Bee venom is a rich source of pharmacologically active substances. In this study, we identified a bumblebee (Bombus ignitus) venom Kunitz-type serine protease inhibitor (Bi-KTI) that acts as a plasmin inhibitor. Bi-KTI showed no detectable inhibitory effect on factor Xa, thrombin, or tPA. However, it strongly inhibited plasmin, although this inhibitory ability was two-fold weaker than that of aprotinin. The activities of B. ignitusvenom serine protease (Bi-VSP) and plasmin in the presence of Bi-KTI indicate that Bi-KTI targets plasmin more specifically than Bi-VSP. These findings demonstrate a novel mechanism for bee venom by which Bi-KTI acts as an antifibrinolytic agent, raising interest in Bi-KTI as a potential clinical agent.

• Young Moo Choo(College of Natural Resources and Life Science, Dong-A University)
• Kwang Sik Lee(College of Natural Resources and Life Science, Dong-A University)
• Hyung Joo Yoon(Department of Agricultural Biology, National Academyof Agricultural Science)
• Byung Rae Jin(College of Natural Resources and Life Science, Dong-A University)