Inhibitory potential of recombinant and native peanut Bowman-Birk inhibitor against proteases of human blood coagulation pathway

Abstract

Plant proteinase/protease inhibitors (PIs) have therapeutic potential besides their role in regulating endogenous protease activity in several physiological processes. They exert their function by inhibiting the catalytic activity of specific proteases. The use of PIs for inhibiting coagulation factors and slowing down the blood coagulation process has emerged as a critical intervention point for developing antithrombotic agents. The present study has demonstrated the characterization of bacterially expressed recombinant peanut Bowman-Birk inhibitor (rPnBBI) and evaluation of its anticoagulant potential compared to native PnBBI (isoinhibitors pool) purified from peanuts. The full-length BBI gene was cloned, and rPnBBI (7.53 kDa) expressed in the soluble fraction of Escherichia coli BL21 (DE3) strain was isolated by passing through the trypsin affinity column. The purified rPnBBI with β-sheets as major secondary structural elements exhibited inhibitory activity towards bovine trypsin and chymotrypsin at diverse pH and temperatures. Both, rPnBBI and PnBBI showed anticoagulant effects by prolonging the activated partial thromboplastin time (aPTT) and inhibiting the activity of proteases/factors (plasma kallikrein, FXIIa, FXIa, FIXa, and FXa) involved in the blood coagulation pathway. Besides, rPnBBI and PnBBI showed a similar inhibitory tendency towards FXIIa, FXIa, and FIXa, while rPnBBI exhibited a higher inhibition potential than PnBBI towards FXa. Contrarily, PnBBI showed higher inhibitory potential than rPnBBI on plasma kallikrein. Altogether, the bioactive BBI molecules from the natural food source peanuts showed significant anticoagulant potential, which could be exploited in the prophylaxis of thromboembolic disorders associated with various human diseases.