Komersová A, Komers K, Zdrazilová P
Department of Physical Chemistry, Faculty of Chemical Technology, University of Pardubice, Czech Republic.
Chem Biol Interact. 2005 Dec 15;157-158:387-8. doi: 10.1016/j.cbi.2005.10.068.
Kinetics of hydrolysis of acetylthiocholine (ATCH) and acetylcholine (ACH) by butyrylcholinesterase (BCHE) and acetylcholinesterase (ACHE) are studied. ATCH is used for testing of enzymatic hydrolysis of ACH in vitro, because mechanism of ATCH hydrolysis is qualitatively similar to ACH and its reaction course can be quantitatively on-line measured by two independent methods: spectrophotometrical (determination of thiocholine - product of ATCH hydrolysis - using Ellman's method) and electrochemical (determination of acetic acid - product of ATCH hydrolysis - by pH-stat method). All tested hydrolyses correspond to the Michaelis-Menten's equation with the second irreversible step up to the total exhaustion of the substrate. The correlations were made by means of differential and integral kinetic equations describing Michaelis-Menten model. The optimal values of Michaelis constant (KM), maximum velocity (Vm), kinetic constants of single reaction steps and absolute concentration of the used enzyme were calculated for each experiment.
研究了丁酰胆碱酯酶（BCHE）和乙酰胆碱酯酶（ACHE）对乙酰硫代胆碱（ATCH）和乙酰胆碱（ACH）的水解动力学。ATCH用于体外ACH酶促水解的测试，因为ATCH水解机制在性质上与ACH相似，并且其反应过程可以通过两种独立方法进行定量在线测量：分光光度法（使用埃尔曼法测定硫代胆碱——ATCH水解产物）和电化学法（通过pH计法测定乙酸——ATCH水解产物）。所有测试的水解均符合米氏方程，直至底物完全耗尽存在第二个不可逆步骤。通过描述米氏模型的微分和积分动力学方程进行相关性分析。针对每个实验计算了米氏常数（KM）、最大速度（Vm）、单反应步骤的动力学常数以及所用酶的绝对浓度的最佳值。
