Ditchfield Robert, Spencer Thomas A
Department of Chemistry, 6128 Burke Laboratory, Dartmouth College, Hanover, NH 03755, USA.
Org Biomol Chem. 2016 Oct 12;14(40):9543-9548. doi: 10.1039/c6ob01761d.
Computational analyses, using primarily density functional theory, have been used to determine the stabilization associated with the carbocation-π interaction of a biochemical carbocation intermediate binding to a phenylalanine residue in an enzyme active site. Studies of complexation between t-butyl cation and ethylbenzene, and of a model of a carbocation intermediate with a phenylalanine in the active site of geranyl diphosphate C-methyl transferase, have afforded the first quantitative evaluation of the stabilization that can be provided to a carbocation by an aromatic residue in an enzymatic reaction. Describing the hydrophobic surrounding medium using a dielectric constant between ε = 2 and ε = 4, the calculated carbocation-π stabilization energy lies in the range of 10-7.5 kcal mol.
主要使用密度泛函理论的计算分析，已被用于确定与生化碳正离子中间体与酶活性位点中的苯丙氨酸残基结合的碳正离子-π相互作用相关的稳定性。对叔丁基阳离子与乙苯之间的络合以及香叶基二磷酸C-甲基转移酶活性位点中碳正离子中间体与苯丙氨酸模型的研究，首次对酶促反应中芳香族残基可提供给碳正离子的稳定性进行了定量评估。使用介于ε = 2和ε = 4之间的介电常数来描述疏水周围介质，计算得到的碳正离子-π稳定能在10 - 7.5千卡/摩尔范围内。
