关键词: 手性对映体, 天冬氨酸, 氢氧根, 水分子, 密度泛函理论, 微扰理论, SMD模型, 能垒

Abstract: Using the dispersion correction density functional ωB97X-D method, the MP2 method of perturbation theory and the SMD model method of selfconsistent reaction field, the title reaction of two stable conformations(Asp_1 and Asp_2) of Asp was investigated. The study of reaction channel and potential energy surface showed that the chiral enantiomer transition was realized by a series of Asp transition states of Hatom abstraction of hydroxyl ion(water clusters) and α-carbon, as well as the rotation of αcarboxy hydroxyl, β-carboxy hydroxyl, β-carboxyl and R-group. The intrinsic energy barrier of the rate-determining step of optical isomerization of Asp_1 and Asp_2 induced by α-H abstraction of hydroxyl ion and H abstraction of water molecule of αcarbon was about 27.0 kJ/mol, and the corresponding intrinsic energy barriers induced by H-atom abstraction of hydroxyl ion assisted with water molecule and H-atom abstraction of two water molecule of α-carbon were about 34.0 and 40.0 kJ/mol, respectively. It could accelerate the process of Asp chiral transition that proton attacks the α-carbon of intermediate carbon anion.

Key words: chiral enantiomer, aspartic, hydroxyl, water molecule, density functional theory, perturbation theory, SMD model, energy barrier