色氨酰酪氨酸缩聚二肽体系的电子转移研究

A Study on the Electron Transfer of Dipeptide

在过渡态理论框架下,用经典轨迹方法、两态模型近似,采用AM1半经验方法及从头算方法探讨了色氨酰酪氨酸缩聚二肽体系的电子转移过程.对于包含桥体的二肽体系的分子内电子转移过程,采用UHF/6-31G水平上电子给体、受体优化结果,和分子轨道电荷定域初始猜测诱导SCF技巧,在UHF/6-31G水平上用线性反应坐标构造出给体、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R约为-0.217,表明气相反应发生在反转区.生物体系电子转移反应的研究对探讨某些生命或生理机制具有十分重要的意义.

Within the framework of the transition state theory,we have discussed the electron transfer in dipeptide by means of the classical trajectory approach and the two-state model.In the determination of the nonadiabatic electron transfer dynamic parameters,the AM1 method and ab initio calculations have been employed.In the double-well potential construction of the intermolecular electron transfer in dipeptide,the geometries of the isolated donor,acceptor,and bridge have been optimized by using ab initio calculation at the level of UHF/6-31G.We have used an electron-localized initial guess to induce the SCF calculation of the whole molecule.It has been found that the crossing of the diabatic potential energy surface appears as long as R takes a value of about-0.217,which implies that the gas-phase occurs in inverted region.The investigation of electron transfer reaction in biologic system is very significant in discussing the physiological mechanism.