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 |
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引用本文: | 谢修银,王志勇,刘欲文,汪存信. 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[J]. 化学学报, 2003, 61(3): 331-335 |
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作者姓名: | 谢修银 王志勇 刘欲文 汪存信 |
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作者单位: | 武汉大学化学与分子科学学院,武汉,430072 |
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基金项目: | 国家自然科学基金(Nos.29873036,30070200)资助项目. |
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摘 要: | 在310.15K,pH=7.0的0.1mol·L~(-1)Na_2HPO_4-NaH_2PO_4缓二者同时存 在时,过氧化氢酶催化H_2O_2分解反应的动力学规律。发现L-抗坏血酸和C~(2+)单 独存在时对酶反应没有明显的抑制作用,二者共存时,对反应有非线性抑制作用。 在一定的酶和底物浓度下,L-抗坏血酸和Cu~(2+)不影响率方程的形式,只减小了一级 反应速率常数.酶活性随抑制剂浓度变化关系呈S形曲线.结合实验结果和文献,提出 了一L-抗坏血酸和Cu~(2+)协同抑制过氧化氢酶的可能机理.
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关 键 词: | 过氧化酶 抗坏血酸 热动力学 协同效应 过氧化氢 抑制 |
修稿时间: | 2002-08-12 |
Thermokinetic Studies on the Cooperative Inhibition of Catalase by L-Ascorbic Acid and Cu2+ |
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Affiliation: | College of Chemistry and Molecular Science,Wuhan University |
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Abstract: | 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. |
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Keywords: | PEROXIDASE ASCORBIC ACID THERMODYNAMICS COOPERATIVITY HYDROGEN PEROXIDE DEPRESSING |
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