Anticoagulant and anticomplement effects of an endogenous inhibitor from hepatopancreas of red king crab (Paralithosed camtschaticus) on human blood

Serpins are the superfamily of serine and cysteine protease inhibitors (SERine Protease Inhibitors) acting by an irreversible suicide mechanism. A novel serpin from hepatopancreas of red king crab (Paralithosed camtschaticus) was isolated and its effect on the process of human blood plasma coagulation was investigated. The investigated serpin exhibited a significant anticoagulant effect, which dramatically increased in the combination with heparin. The study of the crab serpin on C1s (C1 esterase) revealed its competition with the C1 inhibitor from blood plasma. Although the inhibitor weakly influenced thrombin activity, inhibition constant for C1s was (2.02 ± 0.71) 10−7 M. Unlike the C1 inhibitor the novel red king crab serpin does not inhibit fibrinolysis but inhibits blood coagulation. This creates certain clinical perspectives.