THE KINETICS OF THE COMBINATION REACTION BETWEEN ENZYME AND SUBSTRATE——I.STOCHASTIC ANALYSIS,ACTIVATION ENERGY AND MULTIPLE-ACTIVE-SITE
K.-C. Chou · 1977
A stochastic analysis has been made of enzyme-substrate combination reactionsystems.The relationship between diffusion-encounter and effective collision inliquid phase fast reaction systems was discussed.A new formula,derived for calcula-ting the combination rates of multiple-active-site reaction systems,may serve toprovide the theoretical basis for experimentally investigating the combination activa-tion energies of liquid phase fast reaction systems.The results calculated for the fumarase-fumarate reaction system according to theformula are as follows:When the combination activation energy is small,the second-order rate constant calculated under the situation when the four active sites are allopen are nearly the same as that when only one active site is open;only when theactivation energy is large enough will the former be four times the size of the latter.Such a conclusion may also be extended to cover general multiple-active-site reactionsystems.This means that the usual method employed to estimate the combinationrates of multiple-active-site reaction systems is applicable only when the activationenergy is large,but not so when small.In this latter case,the coupling effect amongactive sites cannot be overlooked.Moreover,the transient phase process of enzyme-substrate reaction system hasalso been discussed briefly.