气相环境下K^+催化丙氨酸分子手性对映体转变的机理  

Mechanism of alanine chiral enantiomer transition catalyzed by K^+in gas phase

作　　者：刘芳[1] 马宏源[1] 潘宇[1] 佟华[1] 王佐成[1] LIU Fang;MA Hongyuan;PAN Yu;TONG Hua;WANG Zuocheng(College of Physics,Baicheng Normal University,Baicheng 137000,China)

机构地区：[1]白城师范学院物理学院,吉林白城137000

出　　处：《厦门大学学报（自然科学版）》2020年第6期912-920,共9页Journal of Xiamen University：Natural Science

基　　金：吉林省科技发展计划(20130101308JC,20160101308JC)。

摘　　要：采用密度泛函理论的M06方法研究了气相环境下K^+催化丙氨酸(Ala)分子手性对映体转变反应.反应通道研究发现:Ala稳定构型1的手性转变有a、b、c和d 4个通道,a通道是羧羟基氢向氨基迁移后α-氢以羰基氧为桥迁移,b通道是羧羟基氢向氨基迁移后α-氢向羰基氧迁移再接质子从氨基向α-碳迁移,c通道和d通道是α-氢分别以氨基氮和羰基氧为桥迁移;Ala稳定构型2的手性转变有a和b 2个通道,a通道是α-氢只以羰基氧为桥迁移,b通道是α-氢迁移到羰基氧后氨基的质子再向α-碳迁移.势能面计算表明:构型1手性转变的优势通道是a和b,反应的表观能垒是159.4 kJ/mol;构型2手性转变的优势通道是a,反应的表观能垒是235.8 kJ/mol.结果表明:气相环境下K^+的催化可显著降低Ala手性转变反应的能垒.The reaction of alanine(Ala)chiral enantiomer transition catalyzed by K^+in gas phase has been studied using the M06 method based on the density functional theory.The study of reaction pathways shows that the chiral transition of Ala stable configuration 1 has four pathways,a,b,c and d.In pathway a,α-H is transferred using the carbonyl O atom as a bridge after the transition of carboxy hydroxy hydrogen to the amino group.In pathway b,α-H is transferred to the carbonyl O atom after the transition of carboxy hydroxy hydrogen to the amino group and then the proton transfers from the amino group toα-C.α-H is transferred with the amino N atom and carbonyl O atom as a bridge in pathways c and d,respectively.The chiral transition of Ala stable configuration 2 has two pathways,a and b.α-H is transferred using the carbonyl O atom as a bridge only in pathway a.The proton in the amino group is transferred toα-C afterα-H is transferred to the carbonyl O atom in pathway b.The apparent potential energy barrier is calculated,which shows that the dominant pathways of the chiral transition of configuration 1 are pathway a and b,and the total energy barrier of the reaction is 159.4 kJ/mol.The dominant pathway of the chiral transition of configuration 2 is pathway a,and the total energy barrier of the reaction is 235.8 kJ/mol.The results show that the catalysis of K^+in gas phase can significantly reduce the energy barrier of Ala to achieve chiral transition.

关 键 词：丙氨酸 K^+ 手性转变 密度泛函理论 过渡态 能垒 

分 类 号：O641.12[理学—物理化学]