水液相下Trp分子清除OH自由基反应的DFT研究

Density Functional Theory Study on the Reaction of Hydroxyl Radical and Tryptophan Molecule in Water-Liquid Phase

采用DFT(密度泛函理论)的M06-2X和MN15方法,结合自洽反应场理论的SMD模型方法,研究了水液相下羟自由基(OH)与色氨酸分子(Trp)的反应机制.研究发现:OH可通过抽取Trp的H原子、加成到Trp的不饱和C原子和单电子从Trp分子向OH转移3种途径与Trp分子反应.势能面计算表明:抽H反应能垒在5.6-36.3 kJ/mol之间,加成反应能垒在0-24.4 kJ/mol之间,电子从Trp向OH转移反应的能垒是2.9 kJ/mol.结果表明,水液相下OH极易通过抽H、加成和夺取单电子等3种方式与Trp反应,Trp具有极好的清除OH自由基的作用.

The reaction mechanism of hydroxyl radical(OH)and tryptophan molecule(Trp)in the water-liquid phase was studied by using M06-2X and MN15 methods based on density functional theory and SMD model method based on self-consistent reaction field theory.It was found that OH can react with Trp molecules in three ways:extraction of H atom of Trp,unsaturated C atom added to Trp and single electron transfer from Trp to OH.The potential energy surface calculation shows that the energy barrier of H extraction reaction is between 5.6 and 36.3 k J/mol,the energy barrier of addition reaction is between 0 and 24.4 k J/mol,and the energy barrier of electron transfer from Trp to OH is 2.9 k J/mol,respectively.The results show that OH in the water-liquid phase can easily react with Trp molecule through three processes:H extraction,addition,and single electron capture,Trp molecule has a good function of scavenging hydroxyl radical.