酪胺酸-色胺酸缩聚二肽分子内电子转移速率常数的从头算研究

LONG RANGE ELECTRON TRANSFER IN PEPTIDE: AB INITIO STUDY OF ELECTRON TRANSFER BETWEEN TRYPTOPHAN AND TYROSINE

用量子化学从头算方法对色氨酸 酪氨酸缩聚二肽体系进行电子转移动力学参数的计算。用UHF/ 6 3 1G 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 ,得到两透热势能面在Rc 约为 0处交叉 ,表明气相反应为无能垒过程。采用两态变分法 ,获得了色氨酰酪氨酸及酪氨酰色氨酸体系的分子内电子转移矩阵元VBA分别为 7.1 0J·mol-1和 5 .5 1J·mol-1。采用Marcus双球模型估算了反应的溶剂重组能。

In this article, ab initio calculations have been performed for the evaluation of the kinetic parameters of the electron transfer between tryptophan and tyrosine.At the level of UHF/6 31G *,the geometries of the door,the acceptor,and the spacer have been optimized.A linear reaction coordinate R is used in the construction of the double well potential of the intermolecular electron transfer from the donor to the acceptor.It has been found that the crossing of the two diabatic potential energy surfaces appears as long as R takes a value of about 0,which implies that the gas phase reaction is barrier free.On the basis of variation principle,the values of electron transfer matrices element V BA both trptophyl tyrosine and tyrosyl tryptophan have been determined to be 7.10 J·mol -1 and 5.51J·mol -1 respectively.The solvent reorganization energy has been estimated by Marcus' two spherical model.Rate constats k et at different tempertures have been estimated for the intramolecular electron transfer reactions in tryptophy1-tyrosine and tyrosyl tryptophan.