具有氨基与羧基间单氢键的缬氨酸分子旋光异构及羟自由基致损伤的机理  

Mechanism of Valine Molecules with Mono-hydrogen Bonds between Amino and Carboxyl Groups Optical Isomerism and the Damages Induced by Hydroxyl Radicals

作　　者：郝成欣[1] 汤振宇 吴怡 张育凯 杨晓翠[2] 王佐成[2] HAO Chengxin;TANG Zhenyu;WU Yi;ZHANG Yukai;YANG Xiaocui;WANG Zuocheng(The Pharmacology Department of Basic Ministry,Baicheng Medical College,Baicheng Jilin 137000,China;College of Physics,Baicheng Normal University,Baicheng Jilin 137000,China)

机构地区：[1]白城医学高等专科学校基础部药理教研室,吉林白城137000 [2]白城师范学院物理学院,吉林白城137000

出　　处：《复旦学报（自然科学版）》2018年第6期794-805,812,共13页Journal of Fudan University：Natural Science

基　　金：吉林省科技发展计划自然科学基金(20130101308JC);白城师范学院大学生创新项目(2017006)

摘　　要：在MP2/6-311++G(2df,pd)//B3LYP/6-31+G(d,p)双理论水平,采用自洽反应场(SCRF)理论的SMD模型方法,对标题反应进行了研究.反应通道研究表明:裸环境下缬氨酸的旋光异构可以在3个通道a、b和c实现,a和b分别是α碳上的质子按分步和协同机理以氨基氮为桥迁移,c是α碳上的质子以羰基氧为桥迁移,水环境下只有a和c通道;羟自由基抽氢致缬氨酸损伤只在a通道.势能面计算表明:a通道具有优势,2个和3个水分子簇作氢迁移媒介时,水分子簇对旋光异构反应有极好的催化作用,使反应能垒相对裸反应大幅降低,水溶剂在a通道有较好的助催化作用.水分子辅助羟自由基抽氢致缬氨酸损伤气相反应能垒较低,水溶剂效应使损伤能垒大幅提升.The mechanism of valine molecules with mono-hydrogen bonds between amino and carboxyl groups optical isomerism and the damages induced by hydroxyl radicals were studied by using MP2/6-311+ +G(2 df,pd)//B3 LYP/6-31+G(d,p)dual-theory and SMD model method for self consistent reaction field(SCRF)theory.The study of reaction channels shows that there are three channels a,b and c in the optical isomer reaction of valine at isolation condition.The protons ofα-carbon transfer with N atom of amino groupas bridges by stepwise mechanism and concerted mechanism in channels a and b,while in channel c,the bridge is O atom of carbonyl group.There are only channels a and c in water environment.The hydrogen abstraction reaction which damages the valine molecules happens in channel a only.The potential energy surface calculation show that the channel a is the dominant reaction channel,and when two or three water clusters are used as hydrogen transport medium,they act a good catalytic action on the process of hydrogen-transfer of optical isomerism,and reduce the barrier of reaction vs isolation reaction substantially.Water solution effect has good catalytic activity in channel a.The reaction barrier of hydrogen abstraction reaction which damages the valine molecules with water molecules as assistants is low.The water solvent effect makes the energy barrier of damage enhanced greatly.

关 键 词：旋光异构 缬氨酸 密度泛函理论 过渡态 微扰论 溶剂效应 羟自由基 损伤 

分 类 号：O641.12[理学—物理化学]