THERMODYNAMIC MEASUREMENTS ON THE INTERACTION OF PORCINE TRYPSIN WITH SINGLE-CHAIN AND 2-CHAIN TRYPSIN-INHIBITORS FROM CORN SEEDS

The reactions of the single-and two-chain forms of corn trypsin inhibitor with porcine trypsin in a cacodylate buffer at pH 6.5, 20 °C, both occur with 1: 1 stoichiometry, have association equilibrium constants on the order of 107 M-1, and indistinguishable enthalpy changes lying near 3.6 kcal/mol. The reactions are therefore driven by positive entropy changes. It is suggested that conversion of this inhibitor from its single-to two-chain form involves more than a simple hydrolysis of a peptide bond. © 1979, American Chemical Society. All rights reserved.