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化学学报
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化学学报 ›› 2005, Vol. 63 ›› Issue (2): 121-125. 上一篇    下一篇

研究论文

NaF抑制精氨酸酶催化反应的热动力学研究

谢修银*, 1，王志勇2，汪存信2   

  1. 1长江大学化学与环境工程学院 荆州 434020)
    (2武汉大学化学与分子科学学院 武汉 430072
  • 投稿日期:2004-04-15 修回日期:2004-09-20 发布日期:2010-12-10
  • 通讯作者: 谢修银

Thermokinetic Study on the Inhibition Against Arginase Catalyzed Reaction by NaF

XIE Xiu-Yin*, 1,WANG Zhi-Yong2,WANG Cun-Xin2   

  1. 1 College of Chemistry and Environment Engineering, Yangtze University, Jingzhou 434020)
    (2 College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072
  • Received:2004-04-15 Revised:2004-09-20 Published:2010-12-10
  • Contact: XIE Xiu-Yin

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被引次数

11 | 1

在37 ℃, pH＝7.4～9.4, 40 mmol?L－1的巴比妥钠-HCl缓冲体系中, 利用热动力学方法研究了NaF对精氨酸酶催化L-精氨酸水解反应的抑制作用. 实验结果表明, NaF对精氨酸酶反应的抑制作用, 属于非竞争性可逆抑制, 其抑制率依赖于反应体系的pH值, 底物L-精氨酸和外源Mn2＋离子对相对抑制率和抑制常数的影响不显著. 在pH值为7.4, 外源锰离子浓度分别为0和0.167 mmol?L－1时的抑制常数分别为1.48和1.84 mmol?L－1. F－离子对精氨酸酶的抑制不是与底物L-精氨酸竞争酶的活性位, 而是影响了水分子与双核锰簇的桥式配位作用, 使反应过程中, 作为亲核试剂进攻L-精氨酸胍基碳的羟基离子难于生成或使其浓度减小, 从而降低了酶反应活性.

关键词: 精氨酸酶, 非竞争性可逆抑制, NaF, 热动力学

The inhibition against arginase by NaF was studied by thermokinetic method at 37 ℃, pH＝7.4～9.4, 40 mmol?L－1 sodium barbiturate-HCl buffer solution. As a result, this experiment indicate that the inhibitory effect of NaF towards arginase is a reversible non-competitive inhibition. For the same reaction, the inhibition rate depends only on pH value of solution, while substrate L-arginine and exogenous Mn2＋ ion have no remarkable influence on the inhibition rate. The inhibition constants are 1.48 and 1.84 mmol?L－1 under the condition of exogenous Mn2＋ion concentration of 0 and 0.167 mmol?L－1 respectively. It was suggested that the inhibitory effect do not result from the contest of fluorine anion and L-arginine for the active site of enzyme, and it could be due to that the fluorine anion was in place of (-OH2 binding as a bridging ligand of the arginase double Mn(II) cluster. This effect obstructs the generation of hydroxyl anion that nucleophilically attacks the guanidino carbon of L-arginine and thus inhibits the reaction activity of arginase.

Key words: arginase, reversible non-competitive inhibition, NaF, thermokinetics