The influence of the solvent dielectric properties on the tryptic hydrolysis

L. I. Krishtalik, G. E. Titova, V. V. Topolev

A.N. Frumkin Institute of Electrochemistry, Academy of Sciences of the USSR, Moscow

Abstract: The influence of the solvent dielectric properties on the rate constants of enzymatic reactions is discussed. Two principal effects, changes in the reaction energy and in the reorganization energy, depend differently upon dielectric parameters of the medium. In water-dimethylsulfoxide mixture, the static dielectric constant depends slightly on the organic solvent up to its 50% (by volume) concentration. Therefore, in these mixtures, the main effect is the change of the reorganization energy. The kinetics of trypsin-catalysed hydrolysis of N-benzoyl-L-arginine ethyl ester (including the pH dependence and kinetic isotope effect) in these mixtures has been studied. The maximum acceleration, up to 35%, takes place at 30% concentration of dimethylsulfoxide. The increase in the reaction rate agrees with the effect theoretically calculated.

Russian Journal of Bioorganic Chemistry 1991, 17 (1):66-75

Full Text (PDF, in Russian)