Method for determination of association and dissociation rate constants of reversible bimolecular reactions by isothermal titration calorimeters
Method for determination of association and dissociation rate constants of reversible bimolecular reactions by isothermal titration calorimeters
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DOI：
10.1021/ac062183z
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发表时间：
2007-04-01
影响因子：
7.4
通讯作者：
Yonetani, Takashi
中科院分区：
文献类型：
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作者：
Egawa, Tsuyoshi;Tsuneshige, Antonio;Yonetani, Takashi
可逆双分子反应的速率定律方程可通过缔合和解离速率常数（k(1) 和 k(-1)）描述，在化学计量反应条件下无法求解为简单公式。因此，在伪一级条件下观察此类反应是一种通用技术，这使得反应成为单指数过程，并使我们能够确定 k(1) 和 k(-1)，而无需在化学计量反应条件下分析相同反应所需的任何复杂的迭代计算。然而，伪一级条件下的加速反应速率并不总是有利于采用慢速或中等响应时间的物理化学工具，例如热分析仪器。在本研究中，我们基于等温滴定量热法（ITC）的实验数据，开发了一种简单的非迭代分析方法来确定化学计量条件下可逆双分子反应的k（1）和k（-1），该方法通常用于确定热力学参数而不是动力学常数。我们的方法主要基于滴定过程引起的化学结合的一般原理，即化学弛豫动力学，迄今为止在 ITC 数据的分析中已经考虑了这一原理。
The rate law equation for reversible bimolecular reactions, which are describable by association and dissociation rate constants (k(1) and k(-1)), is not solvable to a plain formula under stoichiometric reaction conditions. Therefore, it is a general technique to observe such reactions under pseudo first-order conditions, which make the reactions a single-exponential process, and enable us to determine k(1) and k(-1) without any complicated iterative computations needed to analyze the same reactions under stoichiometric reaction conditions. However, the accelerated reaction rates under pseudo first-order conditions are not always favorable to the physicochemical tools employing a slow or medium response time, such as thermal analysis instruments. In this study, we have developed a simple non-iterative analytical method to determine k(1) and k(-1) of reversible bimolecular reactions under stoichiometric conditions on the basis of experimental data of isothermal titration calorimetry (ITC), which is generally used to determine thermodynamic parameters rather than kinetic constants. Our method is principally based on the general principle of chemical bindings caused along with the titration processes, that is, the chemical relaxation kinetics, which had been hitherto considered in the analysis on the ITC data.