19F nuclear magnetic resonance studies of the interaction of inhibitors with chymotrypsin. N-Acetyl derivatives of fluorophenylalanines

Abstract

Binding parameters, ΔB and KI, for the three competitive inhibitors N- acetyl-o-fluoro-D-phenyl-alanine, N-acetyl-m-fluoro-D-phenylalanine and N-acetyl-p-fluoro-D-phenylalanine have been determined by Fourier- transform 19F n.m.r, techniques. Association between the enzyme aromatic binding site and the three inhibitors appears to result in greater immobilization of the aromatic rings than is the case for the analogous N-trifluoroacetyl compounds. A balance between the enzyme-inhibitor interactions at the aromatic and amido binding sites is believed to be responsible for the observed effects. The relationship between KI and KS values of inhibitors obtained from kinetic data and KI values obtained by N.M.R. methods is discussed.