Method for Determination of Association and Dissociation Rate Constants of Reversible Bimolecular Reactions by Isothermal Titration Calorimeters

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• 作者：Tsuyoshi Egawa ; Antonio Tsuneshige ; Makoto Suematsu ; Takashi Yonetani
• 刊名：Analytical Chemistry
• 出版年：2007
• 出版时间：April 1, 2007
• 年：2007
• 卷：79
• 期：7
• 页码：2972 - 2978
• 全文大小：406K
• 年卷期：v.79,no.7(April 1, 2007)
• ISSN：1520-6882

文摘

The rate law equation for reversible bimolecular reactions,which are describable by association and dissociation rateconstants (k₁ and k_-1), is not solvable to a plain formulaunder stoichiometric reaction conditions. Therefore, it isa general technique to observe such reactions underpseudo first-order conditions, which make the reactionsa single-exponential process, and enable us to determinek₁ and k_-1 without any complicated iterative computationsneeded to analyze the same reactions under stoichiometric reaction conditions. However, the accelerated reactionrates under pseudo first-order conditions are not alwaysfavorable to the physicochemical tools employing a slowor medium response time, such as thermal analysisinstruments. In this study, we have developed a simplenon-iterative analytical method to determine k₁ and k_-1of reversible bimolecular reactions under stoichiometricconditions on the basis of experimental data of isothermaltitration calorimetry (ITC), which is generally used todetermine thermodynamic parameters rather than kineticconstants. Our method is principally based on the generalprinciple of chemical bindings caused along with thetitration processes, that is, the chemical relaxation kinetics, which had been hitherto considered in the analysison the ITC data.