Analysis of the black-eyed pea trypsin and chymotrypsin inhibitor-alpha-chymotrypsin complex.

The black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) is a member of the Bowman-Birk protease inhibitor (BBI) family. The three-dimensional model of the BTCI-chymotrypsin complex was built based on the homology to Bowman-Birk inhibitors with known structures. An extensive theoretical and experimental study of these known structures has been performed. The model confirms the ideas about Bowman-Birk inhibitor structure-function relations and agrees well with our experimental data (circular dichroism, IR and light scattering). The electrostatic potentials at the enzyme-inhibitor contact surface reveal a pattern of complementary electrostatic potentials from which mutations can be inferred that could give these inhibitors an altered specificity.