大肠杆菌单链DNA结合蛋白与单链聚（脱氧胸苷酸）酸复合物中色氨酸54的三重态亚能级动力学
Triplet state sublevel kinetics of tryptophan 54 in the complex of Escherichia coli single-stranded DNA binding protein with single-stranded poly(deoxythymidylic) acid.
作者信息
Zang L H, Maki A H, Murphy J B, Chase J W
机构信息
Department of Chemistry, University of California, Davis 95616.
出版信息
Biophys J. 1987 Nov;52(5):867-72. doi: 10.1016/S0006-3495(87)83280-0.
The individual sublevel kinetics of the lowest triplet state of tryptophan 54 (Trp 54) which is highly perturbed in the complex of Escherichia coli single-stranded DNA binding protein (Eco SSB) with poly(deoxythymidylic) acid (poly[dT]) have been studied by optically detected magnetic resonance (ODMR) spectroscopy. The triplet sublevel decay constants of Trp 54, kx, ky, kz, are 0.99, 0.072, and 0.045 s-1, respectively, in the poly(dT) complex of a point-mutated Eco SSB in which Trp 88 is substituted by phenylalanine. Tx is the only radiative triplet sublevel. Negative polarity of the Tx----Tz and Tx----Ty phosphorescence-detected ODMR signals results from the steady state population pattern, nx greater than ny, nz, and implies that the relations, px greater than or equal to 14py, and px greater than or equal to 22pz exist for the relative populating rates. Spin-orbit coupling between radiative singlet states and the Tx sublevel of the lowest triplet state of Trp 54 is enhanced selectively upon complexing of Eco SSB with poly(dT).
通过光探测磁共振（ODMR）光谱研究了色氨酸54（Trp 54）最低三重态的各个子能级动力学，该最低三重态在大肠杆菌单链DNA结合蛋白（Eco SSB）与聚（脱氧胸苷酸）（聚[dT]）的复合物中受到高度扰动。在色氨酸88被苯丙氨酸取代的点突变Eco SSB的聚（dT）复合物中，Trp 54的三重态子能级衰减常数kx、ky、kz分别为0.99、0.072和0.045 s-1。Tx是唯一的辐射三重态子能级。Tx----Tz和Tx----Ty磷光探测ODMR信号的负极性源于稳态布居模式，nx大于ny、nz，这意味着相对布居率存在px大于或等于14py以及px大于或等于22pz的关系。当Eco SSB与聚（dT）复合时，辐射单重态与Trp 54最低三重态的Tx子能级之间的自旋-轨道耦合被选择性增强。
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