化学学报 ›› 2001, Vol. 59 ›› Issue (4): 492-495. 上一篇    下一篇

研究论文

微量热法研究过氧化氢酶底物抑制动力学

王志勇;刘欲文;汪存信;张绍辉;屈松生   

  1. 武汉大学化学与环境科学学院
  • 发布日期:2001-04-15

Microcalorimetric studies on the substrate- inhibitory kinetics of catalase

Wang Zhiyong;Liu Yuwen;Wang Cunxin;Zhang Shaohui;Qu Songsheng   

  • Published:2001-04-15

过氧化氢酶是需氧生物体内抗氧化酶系的重要组分。过氧化氢酶催化过氧化氢分解是一个两底物酶促反应,依照Chance提出的机理,反应速率方程具有一级反应方程的形式。此反应在高浓度底物存在的情况下,表现出明显的不可逆底物抑制。本研究用热动力学方法研究了这一反应,提出了一种不可逆底物抑制机理,并应用该机理求出了相关动力学参数。在310.15K,pH=7.0时k0=9.6×10^5L·mol^-1^·s^-1,k1/k2=2.9×10^6。实验结果证明此机理正确有效。

关键词: 过氧化氢酶, 热动力学, 抑制动力学, 量热法

Catalase is an important enzyme of biological defense against oxygen toxicity. It has been detected in a wide range of aerobe. The decomposition of hydrogen peroxide catalyzed by catalase is a bi- substrate enzyme-catalyzed reaction. As Chance proposed, it is an overall first-order reaction. The decomposition of hydrogen peroxide (H2O2) catalyzed by catalase is incomplete under high substrate concentration. It is because that there exists irreversible substrate inhibition of catalase. We proposed a possible irreversible substrate-inhibitory mechanism. Using this mechanism, we studied the kinetics of catalse while the reaction was incomplete. The result is satisfactory. At 310.15K and pH=7.0, k0 and k1/k2 are calculated and to be 9.6×10^5L·mol^-1·s^-1 and 2.9×10^6, respectively.

Key words: CATALASE, THERMODYNAMICS, CALORIMETRY

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