Kinetics of interaction of trypsin with an anionic inhibitor of trypsin BW1-1a from buckwheat seeds

The kinetics of binding of bovine trypsin to a proteinaceous inhibitor of t rypsin from buckwheat seeds (BWI-1a) has been studied. The association rate constant (k(ass)) was 2.2.10(6) M-1 sec(-1) and the dissociation rate cons tant (k(off)) of the enzyme-inhibitor complex was 3.5 10(-3) sec(-1); the i nhibition constant K-i was 1.5 nM, The inhibitor BWI-1a is of the slow, tig htly binding type. The mechanism of the inhibition of bovine trypsin by the trypsin inhibitor BWI-1a was studied. The mechanism of inhibition was foun d to involve two steps according to the kinetic data.