双底物酶促反应的热动力学研究

THERMOKINETIC STUDIES ON DOUBLE SUBSTRATES ENZYME CATALYTIC REACTION

利用微量热方法研究了辣根过氧化物酶(HRP)催化H_2O_2氧化邻苯二胺(OPD)的反应。在298.15K,50mM,pH=7.4的磷酸盐缓冲体系中反应消耗1mol H_2O_2的焓变为227.99kJmol^(-1),而消耗1mol OPD的焓变为439.21kJmol^(-1),HRP对底物H_2O_2的米氏常数K_m(H_2O_2)=2.92mM,对底物OPD的米氏常数K_m(OPD)=0.51mM。

A double substrates enzyme reaction, which horseradish peroxidase (HRP) catalytic oxide of o -phenylenediamine (OPD) by H2O2, were studied by thermokinetic method. At 298.15K, the total molar enthalpies of the reaction are determined to be 227. 99kjmol -1 and 439.21 kjmol -1 respectively when the reaction use up 1 mol H2O2 or 1 mol OPD in 50 mM, pH =7.4 phosphate salt buffer. The Michaelis constants of the reaction are 2.97 mM to H2O2 and 0.51 mM to OPD.