Hammes-Schiffer Sharon
Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Acc Chem Res. 2006 Feb;39(2):93-100. doi: 10.1021/ar040199a.
Theoretical perspectives on hydrogen transfer reactions in enzymes are presented. The proton-coupled electron transfer reaction catalyzed by soybean lipoxygenase and the hydride transfer reaction catalyzed by dihydrofolate reductase are discussed. The first reaction is nonadiabatic and involves two distinct electronic states, while the second reaction is predominantly adiabatic and occurs on the electronic ground state. Theoretical studies indicate that hydrogen tunneling and protein motion play significant roles in both reactions. In both cases, the proton donor-acceptor distance decreases relative to its equilibrium value to enable efficient hydrogen tunneling. Equilibrium thermal motions of the protein lead to conformational changes that facilitate hydrogen transfer, but the nonequilibrium dynamical aspects of these motions have negligible impact.
本文介绍了酶中氢转移反应的理论观点。讨论了大豆脂氧合酶催化的质子耦合电子转移反应和二氢叶酸还原酶催化的氢化物转移反应。第一个反应是非绝热的，涉及两个不同的电子态，而第二个反应主要是绝热的，发生在电子基态上。理论研究表明，氢隧穿和蛋白质运动在这两个反应中都起着重要作用。在这两种情况下，质子供体-受体距离相对于其平衡值减小，以实现有效的氢隧穿。蛋白质的平衡热运动导致构象变化，促进氢转移，但这些运动的非平衡动力学方面的影响可以忽略不计。
