水溶液环境下Phe→Mg(Ⅱ)配合物对映异构的理论研究

The Theoretical Study on the Enantiomerism of Phe→Mg(II)Complex in Aqueous Solution

采用密度泛函理论的M06-2X和MN15方法,结合处理溶剂效应的SMD模型方法,研究了在水溶液环境下苯丙氨酸二价镁配合物(Phe→Mg(Ⅱ))的对映异构.研究发现:Phe→Mg(Ⅱ)的对映异构可在质子以羰基O为桥、以羰基O和氨基N联合为桥和只以氨基N为桥迁移的3个反应通道上实现.计算结果表明:质子只以氨基N为桥迁移的反应通道最具优势,在只考虑水的极性作用时速度决定步骤的自由能垒为212.3 kJ·mol^(-1),在水的极性和水分子(簇)的共同作用下该自由能垒降至108.1~111.5 kJ·mol^(-1).在水溶液环境下Phe→Mg(Ⅱ)的对映异构过程比较缓慢,苯丙氨酸二价镁可短期用于生命体同补苯丙氨酸和金属镁.

The enantiomerism of phenylalanine and magnesium bivalent complexes(Phe→Mg(Ⅱ))in aqueous solution is studied by using the density functional theory-based M06-2X and MN15 methods combined with the SMD model method to deal with solvent effect.The study finds that the enantiomerism of Phe→Mg(Ⅱ)can be achieved in three channels in which the proton uses carbonyl O atom as bridge,the combination of carbonyl O atom and amino N atom as bridge,and merely amino N atom as bridge.The calculation shows that the channel of proton tranfers with amino group N merely as bridge has the most advantage,its free energy barriers of step-determining is 212.3 kJ·mol^(-1)when only the polarity effect of water be considered,the barrier can be reduced to between 108.1 and 111.5 kJ·mol^(-1)under the effect of water polarity and water molecule(clusters).The results show that the enantiomerism process of Phe→Mg(Ⅱ)is relatively slow in aqueous solution,phenylalanine magnesium divalent can be used to supply phenylalanine and magnesium for life simultaneously in short-term dimensions.