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

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 Km and Vmax 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.