The deacylation of substituted benzol-alpha-chymotrypsins.

An extensive comparison of deacylation rates of mono- and disubstituted benzoyl-α-chymotrypsins indicates that no steric effects on rate or apparent pK_a of deacylation are detectable within this series. Some anomalous effects on deacylation rate appear to be associated with fluoro- and nitro-substituents in particular positions on the ring and may be attributable to specific interactions at the enzyme active site. The extensive series of structurally similar acyl-enzymes prepared has allowed a thorough analysis of the effect of acyl group pK_a on the apparent pK_a of deacylation. The data indicates that polar effects on the apparent pK_a are probably negligible. Rho for the deacylation reaction is in good agreement with model reactions for an imidazole general base-catalyzed model reaction.