Slow-binding inhibition: The general case
Slow-binding inhibition: The general case
复制标题
DOI：
10.1016/s0167-4838(96)00118-5
复制
发表时间：
1996-11-14
期刊：
影响因子：
--
通讯作者：
Cleland, WW
中科院分区：
文献类型：
--
作者：
Sculley, MJ;Morrison, JF;Cleland, WW
已经描述了两种基本的动力学机制来解释酶催化反应的缓慢结合抑制。一种机制涉及抑制剂与酶的缓慢相互作用（机制A），而另一种机制涉及酶-抑制剂复合物的快速形成，该复合物经历缓慢的异构化反应（机制B）。但酶和抑制剂的初始相互作用不一定很快，因此游离酶和两种形式的酶抑制剂复合物处于稳态平衡。这一假设将导致机制B的更一般形式。本研究试图通过稳态动力学技术来确定是否有可能区分这三种可能的抑制机制。研究的方法是通过使用决定哪种机制适用的两个速率常数的三种不同比率来推导最一般机制的理论数据。然后将进展曲线数据拟合到描述其他两种机制的速率方程。这些结果引起了人们对推断实验数据符合最一般机理的困难的注意。它们还显示了动力学参数的值，如从描述机制A和B的方程的数据拟合确定的，可以是相当大的误差。
Two basic kinetic mechanisms have been described to account for the slow-binding inhibition of enzyme-catalyzed reactions. One mechanism involves the slow interaction of an inhibitor with enzyme (Mechanism A), while the other involves the rapid formation of an enzyme-inhibitor complex that undergoes a slow isomerization reaction (Mechanism B). But the initial interaction of enzyme and inhibitor may not necessarily be fast so that the free enzyme and the two forms of enzyme inhibitor complex are in steady-state equilibrium. This assumption would give rise to a more general form of Mechanism B. The present study has been concerned with attempts to determine whether it might be possible to distinguish between the three possible inhibition mechanisms by steady-state kinetic techniques, The approach to the investigation has been io derive theoretical data for the most general mechanism by using three different ratios for the two rate constants that determine which mechanism applies, The progress curve data were then fitted to the rate equations that describe the other two mechanisms. The results draw attention to the difficulties of deducing that experimental data conform to the most general mechanism. They also show how the values for the kinetic parameters, as determined from fits of the data to the equations that describe Mechanisms A and B, can be considerably in error.