Experimental evidence for hydrogen tunneling when the isotopic arrhenius prefactor (A(H)/A(D)) is unity.
Experimental evidence for hydrogen tunneling when the isotopic arrhenius prefactor (A(H)/A(D)) is unity.
复制标题
当同位素阿伦尼乌斯前因子 (A(H)/A(D)) 统一时氢隧道效应的实验证据。
DOI：
10.1021/ja806354w
复制
发表时间：
2008
影响因子：
15
通讯作者：
Klinman,JudithP
中科院分区：
文献类型：
--
作者：
Sharma,SudhirC;Klinman,JudithP
动力学同位素效应（KIE）的温度依赖性是研究凝聚相氢隧穿的主要工具之一。氢转移反应具有统一的同位素阿伦尼乌斯前因子比（AH/AD），一般认为这是一种半经典机制。在这里，我们已经确定了大豆脂氧合酶（SLO-1，一种先前被证明遵循量子力学氢隧道的酶）的双突变体，它显示出anAH/ADof的统一性和高度升高的（非经典）KIEs。这一观察结果突出了将氢转移反应分配给仅基于Arrhenius前因子比的半经典模型的缺点
The temperature dependence of the kinetic isotope effect (KIE) is one of the major tools used for the investigation of hydrogen tunneling in condensed phase. Hydrogen transfer reactions displaying isotopic Arrhenius prefactor ratios (AH/AD) of unity are generally ascribed to a semiclassical mechanism. Here, we have identified a double mutant of soybean lipoxygenase (SLO-1, an enzyme previously shown to follow quantum mechanical hydrogen tunneling), that displays anAH/ADof unity and highly elevated (nonclassical) KIEs. This observation highlights the shortcoming of assigning a hydrogen transfer reaction to a semiclassical model based solely on an Arrhenius prefactor ratio