Characterisation of a modified protease inhibitor from dormant Echinocloa seeds

Inhibitor from E. frumentacea seeds was modified on storage as well as by the addition of mercaptoethanol. The trypsin/chymotrypsin inhibitor, totally devoid of antichymotryptic activity, was purified 500 folds with 17% recovery of the antitryptic activity. It was more stable to heat, cooking, changes in pH, and digestion by proteolytic enzymes than the native inhibitor. It formed a complex with trypsin in 1:1 stoichiometric ratio. Both arginyl and lysyl groups were found to be necessary for its action.