缬氨酸分子的手性转变及水分子的催化机理  

Chiral enantiomers transformation of valine and catalytic mechanism of water molecules

作　　者：闫红彦[1] 王佐成[2] 邹晶[3] 佟华[2] 杨晓翠[2] 

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

出　　处：《中山大学学报（自然科学版）》2016年第2期68-75,共8页Acta Scientiarum Naturalium Universitatis Sunyatseni

基　　金：吉林省科技发展计划资助项目(20130101131JC)

摘　　要：采用基于密度泛函理论的B3LYP方法和微扰论的MP2方法,研究了单体缬氨酸分子的手性转变机理及水分子和羟基自由基对氢迁移反应的催化作用。反应通道研究发现:缬氨酸手性对映体转变反应有a、b、c和d四个通道。a和c是手性C碳上的H分别以氨基N和羰基O为桥,迁移到手性碳的另一侧,实现手性转变;b是手性碳上的H依次以羰基O和氨基N为桥,迁移到手性碳另一侧,实现手性转变;d手性碳上的H以羟基O为桥,迁移到手性C的另一侧,实现手性转变。势能面计算表明:a为最具优势反应通道,最高能垒为257.6k J·mol-1;1个水分子、2个水分子链以及1个水分子和羟基自由基构成的链对H迁移反应有较好的催化作用,使a通到上的高能垒分别降为160.3、124.4和104.0 k J·mol-1。结果表明:缬氨酸分子在生命体内的旋光异构主要是在水分子和羟基自由基共同作用下完成的。Based on the B3 LYP methods of density functional theory and the MP2 methods of perturbation theory,the chiral transformation mechanism of the Val monomer molecule,the catalytic effect of water molecules and hydroxyl radicals on the hydrogen transfer reaction were studied. The reaction channel analysis showed that there were four channels a,b,c and d in the Val chiral enantiomer transformation reaction. Channels a and c,the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Amino N and Carbonyl O respectively. Channel b,the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Amino N and Carbonyl O in turn. Channel d,the chiral shift was achieved by the H of chiral carbon transferring to the other side from the bridge of Hydroxyl O. From the calculation of potential energy surface,channel a was the optimal reaction channel,the highest energy barrier is 257. 6 k J·mol^-1. One water molecule,two water molecules chain and the chain of one water molecule and Hydroxyl radical showed better catalytic effect on the H shift reaction,which decreased the high energy barrier in channel a to 160. 3,124. 4 and 104. 0 k J·mol^-1 accordingly. The result revealed that optical isomer of valine molecule in living body was formulized mainly under the joint action of water molecule and hydroxyl radical.

关 键 词：手性 缬氨酸 密度泛函理论 过渡态 微扰论 

分 类 号：O641.12[理学—物理化学]