THE UNUSUAL BEHAVIOR OF THE INHIBITOR S(+)(1-AMINO-2-PHENYLETHYL)PHOSPHONIC ACID TOWARDS CARBOXYPEPTIDASE-A

The molecule (1-Amino-2-phenylethyl)phosphonic acid is shown to inhibit the enzymatic activity of carboxypeptidase A. Through the spectroscopic investigation of the cobalt(II) substituted enzyme we propose that it binds the enzyme in the 1:1 ratio directly at the metal, probably through the phosphate group like phosphate itself. The aromatic group is proposed to sit in the so-called S1 hydrophobic pocket. This is a unique behavior among the inhibitors of the enzyme. The S′1 site is still available in the binary adduct so that a ternary complex can be obtained with molecules like L-Phenylalanine, which enter that site. © 1990.