STUDIES ON BLACK GRAM (Phaseolus mungo L.) TRYPSIN INHIBITOR

ABSTRACT A trypsin inhibitor isolated from black gram (Phaseolus mungo L.) had 75 amino acid residues with an estimated molecular weight of 7892. The kinetic constants K_m and V_max as evaluated by the Dixon and Cornish-Bowden plots were 2.7 × 10^?5and 6 × 10^?3M/min, respectively. The dissociation constants of the enzyme-inhibitor complex (Ki) and the enzyme-inhibitor-substrate complex (Ki') were respectively 4 × 10^?7M and 1.9 × 10^?6M. Trypsin inhibition by black gram trypsin inhibitor was of a linear-mixed type. Chemical modification studies suggested the possible involvement of lysine and arginine at the active site of the inhibitor.