FURTHER CHARACTERIZATION OF THE 12 KDA PROTEASE ALPHA-AMYLASE INHIBITOR PRESENT IN MAIZE SEEDS

A 12 kDa protease/alpha-amylase inhibitor was purified from maize seed s and studied. Its trypsin- and amylase-inhibitor activities against e nzymes from different origins were determined, as well as its optimal pH for inhibition. Eight different proteases, extracted from insects a nd fungi which attack grains during storage, were tested with the inhi bitor. Bovine trypsin and trypsin-like proteases from the insect P. tr uncatus, and the fungi A. niger and A. fumigatus, were recognized by t his inhibitor. Out of 11 alpha-amylases tested, only those from T. cas taneum and C. maculatus were recognized by this inhibitor. The optimal pH's for the inhibition of trypsin and the trypsin-like protease from P. truncatus were 8.0 and 7.5, respectively. The optimal pH activity was 5.0 for the inhibition of amylases from T. castaneum and C. macula tus.