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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 B3LYP method of density functional theory (DFT) was used to study the chiral transition mechanism of lysine in aqueous environment using 6-31 + G (d, p) basis set. In MP2 / 6-31 ++ G p). The study found that there are two reaction channels for the chiral transition of lysine molecules in water environment. One is that the H of chiral carbon is directly transferred to the carbonyl oxygen via the water molecule as a bridge, And then through several heterogeneous processes to achieve chiral transformation; the second is the hydrogen within the carboxyl group in water as a bridge between the carboxyl transfer, and then the chiral carbon H as a bridge to the carbon dioxide oxygen transfer, and then through a series of processes The calculation of the potential energy surface of the reaction shows that the highest energy barrier comes from the H of the chiral carbon to the transition state of the carbonyl oxygen as the bridge of the water, and the energy barrier of the channel 1 with 1H2O and 2H2O as the bridge Respectively, 208.1,177.0 kJ · mol-1. The energy barriers for the chiral transition reaction on the second channel with 1H2O and 2H2O as the bridge were 199.5 and 176.2 kJ · mol-1, respectively, which were higher than that of the monomeric lysine The energy barrier is greatly reduced.The results show that the water molecule has a good catalytic effect on the H-transfer reaction during the chiral transformation of lysine.