天冬氨酸分子在水环境下手性转变机理的理论研究  

The Theoretical Research of Optical Isomerism Mechanism of Aspartic Acid Molecules in Water Environment

作　　者：闫红彦[1] 姜丽莎[2] 佟华[3] 王佐成[3] 刘芳[3] 马宏源[3] 

机构地区：[1]白城师范学院计算机科学学院,白城137000 [2]辽宁师范大学化学与材料学院,大连116000 [3]白城师范学院物理学院,白城137000

出　　处：《复旦学报（自然科学版）》2016年第3期369-380,共12页Journal of Fudan University：Natural Science

基　　金：吉林省科技发展计划资助项目自然科学基金(20130101131JC)

摘　　要：使用密度泛函理论的B3LYP方法和微扰理论的MP2方法,溶剂效应采用离散与连续介质模型,研究了天冬氨酸分子在水环境下的手性转变.反应通道研究发现:天冬氨酸分子在水环境下的手性转变有4个反应通道a,b,c,d.a是以氨基N为桥实现质子转移;b是顺次以羰基O和氨基N为桥实现质子转移;c是只以羰基O为桥实现质子转移;d是羧基内质子迁移后,质子再以羰基O为桥从手性碳的一侧转移到另一侧.势能面计算表明:a通道是最佳通道,3个水分子构成的链作氢迁移媒介,使最高能垒降到108.9kJ·mol-1,对水分子作桥的质子迁移,远程效应不明显;对非质子转移反应,远程作用溶剂效应使能垒明显升高.结果表明:考虑到温度的涨落和分子频繁碰撞等因素,左天冬氨酸在生命体内可以少部分异构成右旋体;水环境下质子迁移反应,可以忽略溶剂的远程效应.Density functional theory, B3LYP method and perturbation theory, MP2 method were used to study mechanism of optical isomerism of aspartic acid molecular in water environment, and using self-consistent reaction field（SCRF） theory, SMD model for the study of solvent effect. The study of reaction channel showed that there were four channels a, b , c and d in the chiral transition reaction. Amino N in channel a is act as the bridge to realize the proton transfer, in the channel b are carbonyl O and amino N play the part of bridge to realize the proton transfer, carbonyl O in channel c is a bridge for achieve the proton transfer, and in the channel d, within the carboxyl proton transfer, proton transfer from one side to another side of chiral carbon rely on carbonyl O as bridge. Potential energy surface calculation shows that channel a is the best channel, a chain forms from three water molecules to be hydrogen transfer medium, it can make the highest barrier down to 108.9 kJ · mol^-1. When the water molecules act as a bridge of proton transfer reaction, solvent effect is not obvious, for the nonproton transfer reaction, solvent effects can make the reaction energy barrier significantly increased. The results show that considering the factors such as temperature fluctuations and molecular collision frequency, a few left-handed aspartie acid in the life can be change to the dextroisomer. To make the research more simple we can ignore the solvent effect when deal with the proton transfer reaction under water environment.

关 键 词：天冬氨酸 手性转变 溶剂效应 密度泛函理论 过渡态 微扰理论 

分 类 号：O641.12[理学—物理化学]