Arrhenius parameters for the alkaline hydrolysis of esters in aqueous solution. Part II. Acetylcholine

Abstract

The kinetics of the alkaline hydrolysis of acetylcholine have been studied using a pH-drop method at 25, 35·5, and 50°, and using a conventional titration technique at 0°. At 25, 35·5, and 50° the hydrolysis was studied over a range of ionic strength. The rate constants and energy and entropy of activation all show the expected dependence on ionic strengths. The effect of charge on rate is discussed with reference to the rate constant and the Arrhenius parameters. From a detailed comparison with the enzymic hydrolysis by acetylcholine esterase, in terms of the available data for the various steps in the reaction sequence postulated for the enzymic reaction, certain trends are noted.