水液相下赖氨酸钙(II)配合物旋光异构的DFT研究

该文采用DFT的M06-2X和MN15方法结合极化介质的SMD模型,研究了在水液相下两性赖氨酸分子2价钙配合物(Lys·Ca(II))的旋光异构.反应通道研究发现:Lys·Ca(II)的旋光异构可在Lys从两性异构为中性后,α-H以氨基N作桥和羰基O作桥迁移的2个通道上实现.势能面计算结果表明:,α-H以氨基N作桥的反应通道最具优势,在隐性水溶剂效应下决速步能垒为220.8 kJ·mol^-1,α-H从手性C向氨基N迁移的过渡态在显性水溶剂效应下的能垒降至120.5 kJ·mol^-1左右.研究结果表明:在水液相下手性Lys·Ca(II)的消旋过程十分缓慢,其用于生命体同补Lys和Ca(II)具有较好的安全性.

The Density Function Theoretical Study on the Optical Isomerism of Lysine Ca(II)Complex in Water-Liquid Phase Environment

The optical isomerism mechanism of amphoteric lysine(Lys)and divalent calcium(Ca(II))complexes(Lys·Ca(II))in water-liquid phase environment is studied by means of M06 and MN15 methods based on density functional theory and SMD model method of polarized continuum.The study of reaction channels shows that the optical isomerism of Lys·Ca(II)can be achieved on two channels that are α-H proton transfers with amino group N as a bridge after the amphoteric Lys isomerizes to neutral Lys,and α-H proton directly uses carbonyl O atom as the transfer bridge to achieve reaction.Investigation on the potential energy surface shows that the first reaction channel has the most advantage,the free energy barrier of the rate-determining step is 220.8 kJ·mol^-1 under the effect of recessive solvent,it comes from the transient state of the proton moving from α-C to amino group N,the energy barrier is reduced to about 120.5 kJ·mol^-1 under the effect of dominant solvent.The results show that chiral Lys·Ca(II)racemization process is very slow,it is relatively safe to be used to supply Lys and Ca(II)for life simultaneously.