Rate enhancement specificity with .alpha.-chymotrypsin: temperature dependence of deacylation

Abstract

The relative rate of the hydrolysis of 2-(5-n-aklyl)furoyl-.alpha.-chymotrypsin reaches a maximum with the propyl derivative. The Arrhenius plots for the hydrolyses of the 2-furoyl-, 2-(5-ethyl)furoyl- and 2-(5-n-propyl)furoyl-.alpha.-chymotrypsins display a discontinuity, while the plots obtained with the remaining furoyl derivatives 5-methyl, 5-n-butyl and 5-n-amyl are linear. The deacylation of the furoyl derivatives of .alpha.-chymotrypsin probably involves a minimum of 2 elementary reaction steps. Depending upon the reaction conditions, rate enhancement specificity appears to be either entropy or enthalpy controlled.