Measuring and Predicting Thermodynamic Limitation of an Alcohol Dehydrogenase Reaction
Measuring and Predicting Thermodynamic Limitation of an Alcohol Dehydrogenase Reaction
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DOI：
10.1021/acs.iecr.7b01228
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发表时间：
2017-05-17
影响因子：
4.2
通讯作者：
Held, Christoph
中科院分区：
文献类型：
--
作者：
Voges, Matthias;Fischer, Florian;Held, Christoph
了解酶反应的热力学限制及其影响因素对于提高时空产率和减少溶剂用量或能耗的过程优化是至关重要的。本文研究了乙醇脱氢酶在水溶液中催化苯乙酮和异丙醇合成1-苯乙醇和丙酮的反应，反应温度为293.15-303.15 K，pH为7。该反应是一个模型反应，用生物热力学来研究和预测酶反应的局限性。测量了不同反应条件(温度、初始反应物摩尔比)下的平衡反应物的实验摩尔分数，得到了反应平衡位置(Km)。研究中苯乙酮的最大初始摩尔浓度为0：02mol.kg(-1)，由于溶解度的限制，2-丙烷过量1-50倍。结果表明，Km强烈依赖于初始反应物摩尔浓度和反应温度。实验K-m值在0.20-0.49之间。热力学的关键性质(热力学平衡常数、标准吉布斯能和标准反应热)是由测定的K-m值和用热力学模型EPC-SAFT预测的反应物的活度系数确定的。此外，还利用EPC-SAFT对不同初始摩尔分数的K-m进行了预测。实验结果和预测结果在定量上是一致的(实验值与预测值的均方根误差为0.053)，这表明在工业应用中，EPC-SAFT是一种很有前途的工具，可以用来识别可能增加或降低K-m值的工艺条件，从而改变反应的位置。
The knowledge of thermodynamic limitations on enzymatic reactions and of influencing factors thereon is essential for process optimization to increase space-time yield's and to reduce the amount of solvent or energy consumption. In this work, the alcohol dehydrogenase (ADH) catalyzed reaction from acetophenone and 2-propanol to 1-phenylethanol and acetone in aqueous solution was investigated in a temperature range of 293.15-303.15 K at pH 7. It serves as a model reaction to demonstrate the use of biothermodynamics in order to investigate and predict limitations of enzymatic reactions. Experimental molalities of the reacting agents at equilibrium were measured yielding the position of reaction equilibrium (Km) at different reaction conditions (temperature, initial reactant molalities). The maximum initial acetophenone molality under investigation was 0:02 mol.kg(-1) due to solubility limitations with a 1- to 50-fold excess of 2-propana It was shown that Km strongly depends on the initial reactant molalities as well as on reaction temperature. Experimental K-m values were in the range of 0.20 to 0.49. Thermodynamic key properties (thermodynamic equilibrium constant, standard Gibbs energy and standard enthalpy of reaction) were:determined by measured K-m values and activity coefficients of the reacting agents predicted with the thermodynamic model ePC-SAFT. In addition, ePC-SAFT was used to predict K-m at different initial molalities. Experimental and predicted results were in quantitative agreement (root-mean-square error of experimental versus predicted K-m was 0.053), showing that ePC-SAFT is a promising tool to identify process conditions that might increase/decrease K-m values and, thus, shift the position of reactions for industrial applications.