Inhibits B.lichenoformis subtilisin, B.subtilis subtilisin, bovine pancreatic alpha-chymotrypsin and porcine alpha-chymotrypsin with Ki of 3.92 nM, 5.70 nM, 7.24 nM and 9.35 nM respectively. B.lichenoformis subtilisin is inhibited with a molar ratio of 1:0.87. Also inhibits chymotrypsin-like activities from the digestive tracts of the insect larvae T.molitor, P.interpunctella and H.armigera. Does not inhibit bovine pancreatic trypsin, porcine pancreatic elastase, or human leukocyte elastase. Optimum temperature is 25 degrees Celsius when incubation is carried out at pH 7.0-9.0. Monomer. Belongs to the protease inhibitor I13 (potato type I serine protease inhibitor) family.