KINETIC CHARACTERIZATION OF hK6 INHIBITION BY PROTEASE INHIBITOR, SOYBEAN

The kinetic characteristics, of interaction between hK6 (human Kallikrein) and soybean (BBI) , protease inhibitor and antitumor agent , in the presence of substrate (Phenylalanine –Serine-Arginine)-(7-amino-4- methyl-coumarin) (FSR-AMC) were investigated. The hK6 were found to bind soybean in two reversible steps, by slow binding inhibition mechanism. The Ki of the first step binding was 13 nM and Ki* of the second binding step was 1.6 nM. The microcopic rate constants were calculated as follows: 311 M-1.S-1 for k3 , 0.04×10-6 M-1.S-1 for k –3 , 0.2×10-6 S-1 for k 4 and 0.025×10-6 S-1 for k-4 respectively.The results suggested that the interaction mechanism between hK6 and soybean was like that of trypsin with this inhibitor but with rather lower inhibitory constants values.