细胞色素P450 2E1催化下乙醛羟基化反应动力学同位素效应的理论研究

A theoretical study of kinetic isotope effects in acetalde hyde hydroxylation by cytochrome P450 2E1

采用建立在Eyring绝对反应速率理论基础上的计算模型,对细胞色素P4502E1催化下乙醛羟基化反应动力学同位素效应进行了理论研究.计算表明,乙醛羟基化反应的动力学同位素效应大小约为5.0(Wigner量子校正后约为7.0左右),远比烷烃羟基化反应的动力学同位素效应要小的多.这个反应对温度比较敏感,所以反应存在明显的量子隧穿现象.文中还对动力学同位素效应给出了相应的过渡态构型方面的解释.

Kinetic isotope effects （KIEs） of acetaldehyde hydroxylation by Cytochrome P450 2El were studied with a method based on Eyring＇s absolute reaction rate theory. The calculated KIEs are ca. 5.0, which is a typical value of hydrogen atom abstraction process. The calculated values are consisted with the experimental results. KIEs of this reaction are also sensitive to the temperature, which means that there is obvious quantum tunneling occurred in this reaction. Related explanations based on the transition state geometries were also presented.