We studied the chiral transition mechanism of lysine molecules and the catalysis of water molecules and hydroxyl radicals on the hydrogen transfer reaction based on amino as proton transfer bridge by using the B3LYP methods of density functional theory and the MP2 methods of perturbation theory.The results show that there are two channels a,b in the chiral transition reaction of lysine. The channel a is the dominant reaction channel,where the Gibbs free energy barrier of naked reaction of rate determining step is 252.6 kJ/mol.Besides,the chain composed of two water molecules and the chain composed of hydroxyl radicals and water molecules have a better catalysis in hydrogen migration,which make the free energy barrier be reduced to 1 1 9.5 kJ/mol and 98.5 kJ/mol respectively.So the water molecules and hydroxyl radicals have good catalysis on the hydrogen transfer in lysine molecules and this is the main reasons of leading to the heterogeneous of L-lysine that there is hydroxyl radical in life body.%采用密度泛函理论的 B3LYP 方法和微扰理论的 MP2方法,考察赖氨酸分子基于氨基作为质子转移桥梁的手性转变机理以及水分子和羟基自由基对氢迁移反应的催化作用.结果表明,赖氨酸分子手性转变有2个通道 a 和 b,通道 a 为主反应通道,决速步骤裸反应 Gibbs自由能垒为252.6 kJ/mol,2个水分子构成的链以及羟基自由基和水分子构成的链使通道 a决速步骤的自由能垒分别降为119.5,98.5 kJ/mol.表明水分子和羟自由基对 H 迁移反应有较好的催化作用,生命体内的羟基自由基是导致左旋赖氨酸旋光异构的主要原因.
展开▼
