Purification and characterization of protease inhibitors from peanuts (Arachis hypogaea)

Five protease inhibitors were isolated from peanut seeds and named A-I, A-II, B-I, B-II, and B-III. These inhibitors seemed to be Bowman-Birk type inhibitors judging from their low molecular weights and high cystine contents. All the inhibitors inhibited both bovine trypsin and chymotrypsin at ratios of 1:2 and 1:1, respectively, but not simultaneously. The complexes of the inhibitors and trypsin no longer inhibit chymotrypsin. On the other hand, their complexes with chymotrypsin inhibit trypsin with a slow release of chymotrypsin.