Abstract: Using MP2/6-311++G(2-df,pd-)//B3LYP/6-31+G(d,p) double theory and SMD model method for self consistent reaction field (SCRF) theory, we studied the optical isomerism process of two stable conformation lysine molecules based on amino nitrogen as hydrogen transport bridge in water liquid phase environment. The calculation of potential energy surface shows when the two and three water clusters are used as hydrogen transport medium, the ratedetermining step Gibbs free energy barriers of conformation 1 optical isomer are 11602,11271 kJ/mol, respectively. The ratedetermining step Gibbs free energy barriers of conformation 2 optical isomer are 11027,11429 kJ/mol, respectively. When hydroxyl radical and water molecule chain are used as hydrogen transport medium, the Gibbs free energy barriers of conformation 1 and 2 damage induced by hydroxyl radical pumping hydrogen are -5306,-5605 kJ/mol, indicating no barrier reaction. The results show that under the water liquid phase environment, lysine molecules can be slowly optical isomers, and hydroxyl radicals can quickly cause lysine damage.

Key words: optical isomers, lysine, density functional theory, transition state, perturbation theory, Gibbs free energy, hydroxyl radical, damage