摘要
使用密度泛函理论的B3LYP方法,采用6-31+G(d,p)基组,研究了水环境下赖氨酸分子的手性转变机制,在MP2/6-31++G(d,p)水平计算了单点能.反应通道研究发现:水环境下赖氨酸分子的手性转变有两个反应通道,一是手性碳的H以水分子为桥梁直接转移至羰基氧上,然后经过几个异构过程实现手性转变;二是羧基内的氢先以水分子为桥梁在羧基内转移,而后手性碳的H以水分子为桥梁转移至羰基氧,再经一系列过程实现手性转变.反应过程的势能面计算表明:最高能垒均来自手性碳的H以水分子为桥转移至羰基氧的过渡态,在第1通道以1H2O和2H2O为桥时的能垒分别为208.1,177.0 k J·mol-1,在第2通道以1H2O和2H2O为桥手性转变反应的能垒分别为199.5,176.2 k J·mol-1,均较单体赖氨酸分子时的能垒大幅降低.结果表明,水分子对赖氨酸手性转变过程中的H转移反应有较好的催化作用.
The chiral shift mechanism of lysine molecules under water environment is researched by using 6-31 ＋G（ d,p） basis set,which is based on the method of density functional theory B3 LYP. At the same time,the energies of single points are calculated at the MP2 /6-31 ＋ ＋ G（ d,p） level. It is found that there are two reaction channels during the process of chiral shift under water environment. On the first channel,hydrogen directly transfers from chiral carbon to carbonyl oxygen through the medium of water molecules,then the lysine molecule achieves chiral shift after several isomate processes. On the second channel,hydrogen on hydroxyl firstly transfers inside hydroxyl,then hydrogen on the chiral carbon transfers to carbonyl oxygen using the medium of water molecules. Finally through a series of processes,the chiral transition is completed. The calculation of potential energy surfaces during the reactions indicates that the maximum energy barriers of two channels are both from the transition states that hydrogen transfers from chiral carbon to carbonyl oxygen using the medium of water molecules. The energy barriers on the first channel are 208. 1 k J·mol^-1 and 177. 0 k J·mol^-1 respectively to correspond to the processes using 1H2 O and 2H2 O as mediums. Similarly,the energy barriers on the second channel are 199. 5 k J· mol- 1and 176. 2 k J· mol^-1 respectively to correspond to the two situations. Compared with the reactive energies 323. 3k J· mol^-1 and 314. 1 k J· mol^-1 of monomer situation on two channels,the reactive energies of lysine under water environment are lower. The results show that,water plays an important pole in catalyzing hydrogen transfer reaction during the chiral shift of lysine molecule.
出处
《武汉大学学报（理学版）》
CAS
CSCD
北大核心
2015年第5期491-496,共6页
Journal of Wuhan University:Natural Science Edition
基金
吉林省自然科学基金(20130101131JC)资助项目
