The nature of interaction between the carboxylate of substrates and the guanidinium moiety of Arg-145 in carboxypeptidase a probed by inhibitors of the enzyme

Article abstract of DOI:10.1016/S0960-894X(96)00541-0

Replacement of the α-proton of 2-benzyl-3-hydroxypropanoic acid, a competitive inhibitor of carboxypeptidase A with a fluoro group brought about a 2-fold increase in K(i) value (0.61 mM → 1.19 mM), while pK(a) value decreased by 1.4 units (4.36 → 2.95), suggesting that the carboxylate of the inhibitor and that of substrates as well as hydrogen bonded to the guanidinium moiety of Arg-145 of the enzyme.