论文标题
牛磺酸羟基化过程中的原子隧道/$α$ - 酮戊二酸二氧酶通过量子力学/分子力学模拟鉴定
Atom Tunneling in the Hydroxylation Process of Taurine/$α$-Ketoglutarate Dioxygenase Identified by Quantum Mechanics/Molecular Mechanics Simulations
论文作者
论文摘要
TAUD二氧酶是研究最多的$α$ -Ketoglutarate依赖性二氧酶（$α$ kgds）之一，涉及多种生物技术应用。我们通过QM/mm方法（B3LYP/CHARMM22）研究了$α$ kGD的催化周期的关键步骤。反应过程中电荷和自旋密度的分析表明，发生了一种协同的机理，其中H原子转移与从牛磺酸到Fe = O辅助因子的电子转移同时进行。我们发现氢原子的量子隧穿，在5 \ textcelsius {}时将速率常数增加40倍。结果，获得了接近60的KIE值，这与实验值一致。
TauD dioxygenase is one of the most studied $α$-ketoglutarate dependent dioxygenases ($α$KGDs), involved in several biotechnological applications. We investigated the key step in the catalytic cycle of the $α$KGDs, the hydrogen transfer process, by a QM/MM approach (B3LYP/CHARMM22). Analysis of the charge and spin densities during the reaction demonstrates that a concerted mechanism takes place, where the H atom transfer happens simultaneously with the electron transfer from taurine to the Fe=O cofactor. We found quantum tunneling of the hydrogen atom to increase the rate constant by a factor of 40 at 5\textcelsius{}. As a consequence a quite high KIE value of close to 60 is obtained, which is consistent with the experimental value.
