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采用密度泛函理论的B3LYP方法和微扰理论的MP2方法研究了单体半胱氨酸分子手性转变机理及水分子对氢迁移反应的催化作用.根据研究结果,半胱氨酸分子手性转变反应有4个通道:a通道是手性C上的H只以氨基N为桥转移至手性C另一侧;b通道是手性C上的H依次以羰基O和氨基N为桥转移至手性碳另一侧;c通道是手性C上的H只以羰基O为桥转移至手性碳另一侧;d通道是手性C上的H以羟基O为桥转移至手性碳另一侧.势能面计算表明:a通道为优势反应通道,最高能垒254.6kJ·mol~(-1);1个水分子及2个水分子构成的链作为H迁移媒介,使最高能垒降至163.2和126.2kJ·mol~(-1),说明水分子对H迁移反应具有较好的催化作用.
The mechanism of monomeric cysteine chiral transition and the catalysis of water molecules on the migration of hydrogen have been investigated by using the density functional theory B3LYP method and the perturbation theory MP2 method.According to the results of the study, the cysteine chirality The transition reaction has 4 channels: a channel is chiral C on the H only to amino N bridge transfer to the other side of chiral C; b channel chiral C on H in order to carbonyl O and amino N bridge transfer To the other side of the chiral carbon; c channel is chiral C on the H only carbonyl O bridge transfer to the other side of the chiral carbon; d channel is chiral C on the H to hydroxyl O bridge transfer to chiral Potential energy surface calculation shows that: a channel is the dominant reaction channel with the highest energy barrier of 254.6 kJ · mol -1; and the chain composed of one water molecule and two water molecules acts as H transport medium, Base to 163.2 and 126.2kJ · mol ~ (-1), indicating that water molecules have a good catalytic effect on the migration of H.