肽链体系中的长程电子转移酪氨酸与色氨酸间电子转移的理论研究  

Long - Range Electron Transfer in Peptides A Theoretical Study of Electron Transfer between Tryptophan and Tyrosine

作　　者：李象远[1] 刘萍云[1] 李鲲 何福城 

机构地区：[1]四川大学应用化学系,成都610065

出　　处：《化学学报》1999年第7期724-729,共6页Acta Chimica Sinica

基　　金：国家自然科学基金(29706104;29573112)资助项目

摘　　要：用电子转移的半经典模型和量子化学半经验方法对色氨酸-酪氨酸二肽体系进行电子转移动力学参数计算.用AM1方法分别优化给体、受体和桥体的几何构型,用线性反应坐标构造了给体和受体分子间电子转移的双势阱,得到两透热势能面交叉处的反应坐标为R≈0.10,并确定了反应的内重组能及反应热.对色氨酰酪氨酸和酪氨酰色氨酸体系进行闭壳层HF自洽场计算,按Koopmans定理计算体系分子轨道分裂能值△,在R约为O处发现了△的极小值,从而获得色氨酰酪氨酸及酪氨酰色氨酸体系分子内电子转移的电子转移矩阵元V_(DA)分别为0.96kJ·mol^(-1)和0.87kJ·mol^(-1).采用Marcus双球模型估算反应的溶剂重组能为64.60kJ·mol^(-1).Based on the semiclassical model of the electron transfer, kinetic parameters of the electron transfer between tryptophan and tyrosine have been calculated by using the AMI semi - empirical method. Optimization of the systems of the donor, the acceptor, and the bridge has been performed. A linear reaction coordinate R is used in the construction of the double - well potential for the intermoleculai' electron transfer from phenol anion radical to indole radical. It has been found that the crossing of the two diabatic potential energy surfaces appears at R = 0. 10. The inner reorganization energy and the exothermicity of the reaction are then determined. Closed shell HF SCF calculations have been carried out for the systems Tryptophyl - Tyrosine and Tyrosyl - Tryptophan for different values of R,and the Koopmans' theorem is invoked to estimate the energy level splitting A . From the obtained △min,the values of electron transfer matrix element VDA are determined to be 0.96kJ·mol-1 and 0.87kJ·mol-1 for Tryptophyl - Tyrosine and Tyrosyl - Tryptophan, respectively. The solvent reorganization energy has been estimated to be 64.60kJ mol-1 according to Marcus' two - spherical model.

关 键 词：二肽 肽链 酪氨酸 色氨酸 电子转移 

分 类 号：Q516.02[生物学—生物化学]