Activation Free Energies of Enzymatic Reactions; Simulations and Experiments

Abstract

The validity of the empirical valence bond (EVB) simulation method for the calcn. of enzyme activation energies was tested with a trypsin mutant contg. glycine (Gly)-216 -> alanine (Ala) and Gly-226 -> Ala substitutions. The mutation evidently leads to changes in the oxyanion hole of the enzyme; these changes reduce the electrostatic stabilization of the oxyanion intermediate. Application of the EVB method (along with an umbrella sampling procedure) for calcn. of the free energies of the main resonance structures in the enzyme reaction gave results which appeared to reproduce exptl. results. [on SciFinder (R)]