A spectrophotometric assay for the characterization of the S′ subsite specificity of α-chymotrypsin

The partitioning of maleylphenylalanine-α-chymotrypsin formed using maleylphenylalanine methyl ester as acyl donor between amino acid-derived nucleophiles and water was determined spectrophotometrically. The interpretation of the results obtained from graphical analysis gave evidence of a high conformational specificity of α-chymotrypsin towards basic amino acid derivatives in the P′ 1 position including significant differences between the amide and methyl ester of arginine. Amides of neutral amino acids with large side-chains show higher nucleophile reactivity in comparison with glycine amide.