The explanation of high specificity of discriminating optical isomers in enzymatic reactions by the molecular anvil model of enzyme

Abstract

The molecular anvil model of enzyme is proposed and applied to explain high specificity of discriminating optical isomers in enzymatic reactions. The molecular anvil is a mechanism which can accumulate energy from two interacting molecules and produce locally a high energy spot called anvil site. Two conditions neccessary for formation of the molecular anvil are described. For a pair of enzyme and substrate molecules these two conditions are considered to be satisfied. Assuming proper shapes and sizes for molecules of optical isomers and a hole on the surface of the enzyme molecule into which the optical isomers can fit and also assuming Lenard-Jones 12-6 type potential for each pair of interacting molecular sites. The amount of energy accumulated at the anvil site is calculated. Following the assumption that the total reactivity is determined by binding process and chemical process in which the accumulated energy at the anvil site is utilized to enhance the reaction, total reactivities for L- and D-isomers are calculated and the values of specificity of discriminating L-isomer from D-isomer are derived for various values of interaction energy. It is shown that the molecular anvil plays an important role in elevating specificity as well as producing high catalytic power of enzyme.