Inhibitor of trypsin and human plasma kallikrein with a Ki of 2.9 nM and 14.0 nM, respectively. Does not inhibit chymotrypsin, porcine pancreatic elastas, human neutrophil elastase, coagulation factor Xa, human thrombin, porcine pancreatic kallikrein or plasmin. Belongs to the leguminous Kunitz-type inhibitor family.