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化学学报
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化学学报 ›› 1996, Vol. 54 ›› Issue (1): 38-44. 上一篇    下一篇

研究论文

微量热法研究单底物酶促反应的产物抑制作用

梁毅;汪存信;吴鼎泉;屈松生   

  1. 武汉大学化学系
  • 发布日期:1996-01-15

Microcalorimetry applied to the study of product inhibition of single-substrate enzyme-catalyzed reactions

LIANG YI;WANG CUNXIN;WU DINGQUAN;QU SONGSHENG   

  • Published:1996-01-15

PDF

676

被引次数

20 | 6

本文建立了有产物抑制的单底物酶促反应动力学的对比进度方程和热力学的数学模型。根据此模型, 可由反应的热谱曲线方便地解析出动力学参数(K~m, K~i和V~m)和摩尔反应焓(△~rH~m), 并同时确定产物的抑制类型。用微量热法研究了精氨酸酶催化水解L-精氨酸的热动力学, 确定水解产物L-鸟氨酸属于竞争性可逆抑制剂, 298.15K和pH 9.4时L-鸟氨酸与精氨酸酶作用的抑制常数K~i=1.22×10^-^3mol·L^-^1。实验结果验证了本文有产物抑制的单底物酶促反应热动力学研究法的正确性。

关键词: 精氨酸酶, 热动力学, 微量热法, 对比进度法, 酶促反应, 产物抑制

Reduced extent equations for kinetics of single-substrate product- inhibited enzyme-catalyzed reactions and mathematical model for thermokinetics have been suggested. By analyzing the thermograms of these reactions, this model can be conveniently used to calculate both kinetic parameters (K~m, K~i and V~m) and molar enthalpy (△~rH~m), and to establish the type of product inhibition simultaneously. Thermokinetics of arginase-catalyzed hydrolysis of L-arginine was studied by microcalorimetry, and the reaction product, L-ornithine, was established as a competitive reversible inhibitor. At 298.15K and pH 9.4, the K~i value for L-ornithine was 1.22×10^-^3mol·L^-^1. The reliability of this method for thermokinetics of single-substrate product-inhibited enzyme-catalyzed reactions has been verified by the experimental results.

Key words: ARGINASE, THERMODYNAMICS, MICROCALORIMETRIC METHOD

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