丝氨酸构象异构化机理的密度泛函理论研究

Density Function Theoretical Study on Isomerization Reaction Mechanism of Serine

采用M06/6-31++G^**方法研究了丝氨酸构象异构化机理,得到15种丝氨酸稳定构象和15个过渡态。构象间可以通过分子内化学键的旋转相互转化,氨基旋转的能垒低于10.16 kJ?mol-1;C-C键旋转的能垒低于23.31 kJ·mol^-1,侧链羟基旋转的能垒低于24.13 kJ·mol^-1,羧羟基的旋转能垒在39.68~54.80 kJ·mol^-1之间。最稳定构象A转化为次稳定构象B的路径为A→A-O→O→N-O→N→I-N→I→I-J→J→D-J→D→D-H→H→G-H→G→B-G→B,该路径的最高能垒为54.80 kJ·mol^-1。

Biological activity of amino acid molecule is closely related to their conformations.M06/6-31++G**method was applied to investigate the isomerization reaction mechanism of serine conformations.15 stable conformations and 15 transition states were obtained after the full optimization and the reaction paths were found.Isomerization reaction is induced by the rotation of chemical bond.Energy barrier of rotation of the C-N bond is less than 10.16 kJ·mol^-1,which of C-C bond is less than 23.31 kJ·mol^-1,which of the side chain hydroxyl is less than 24.13 kJ·mol^-1,and the energy barrier range of rotation of the carboxy hydroxyl is 39.68~54.80 kJ·mol^-1.The path from the most stable conformation to the second stable conformation is A→A-O→O→N-O→N→I-N→I→I-J→J→D-J→D→D-H→H→G-H→G→B-G→B,and the highest energy barrier of this path is 54.80 kJ·mol^-1.