Acta Chimica Sinica ›› 2003, Vol. 61 ›› Issue (3): 331-335. Previous Articles     Next Articles

Original Articles

热动力学研究L-抗坏血酸和Cu~2+对过氧化氢酶的协同抑制

谢修银;王志勇;刘欲文;汪存信   

  1. 武汉大学化学与分子科学学院
  • 发布日期:2003-03-15

Thermokinetic Studies on the Cooperative Inhibition of Catalase by L-Ascorbic Acid and Cu2+

Xie Xiuyin;Wang Zhiyong;Liu Yuwen;Wang Cunxin   

  1. College of Chemistry and Molecular Science,Wuhan University
  • Published:2003-03-15

The reaction of catalase catalyzed decomposition of H_2O_2 was studied by thermokinetic method in 0.1 mol·L~1 Na2HP04-NaH2P04 buffer solution at 310.15 K and pH 7.0 in the presence of L-ascorbic acid or Cu~(2+) or of the both. There is no apparent inhibition effect on catalase when L-ascorbic acid or Cu~(2+) is present solely. However, when they are present simultaneously, a non-linear inhibition of the reaction can be observed. At definite enzyme and substrate concentrations, L-ascorbic acid and Cu~(2+) have no effect on the form of kinetic equation of the overall reaction. In other words, the overall reaction of HjC^ decomposition catalyzed by catalase is according to pseudo-first order rate equation when L-ascorbic and Cu~ (2+) are present or absent, but the rate constant decrease when the concentrations of L-ascorbic and Cu~(2+) increase. Dose relation of the enzyme activity with the concentrations of L-ascorbic and Cu~(2+) is a sigmoidal curve. Combined the results of this experiment with the conclusions of literatures, a possible mechanism of L-ascorbic acid and Cu~(2+) cooperative inhibition on catalase was proposed.

Key words: PEROXIDASE, ASCORBIC ACID, THERMODYNAMICS, COOPERATIVITY, HYDROGEN PEROXIDE, DEPRESSING

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