Electric-field dependent decays of two spectroscopically different M-states of photosensory rhodopsin II from Natronobacterium pharaonis.
Electric-field dependent decays of two spectroscopically different M-states of photosensory rhodopsin II from Natronobacterium pharaonis.
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来自法老嗜盐杆菌的光感视紫红质 II 的两种光谱不同 M 态的电场依赖性衰变。
DOI：
10.1016/s0006-3495(03)75114-5
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发表时间：
2003
影响因子：
3.4
通讯作者：
P. Hildebrandt
中科院分区：
文献类型：
--
作者：
L. Rivas;Silke Hippler;M. Engelhard;P. Hildebrandt
用共振拉曼（RR）光谱技术研究了来自嗜盐杆菌的感觉视紫红质Ⅱ（NpSR Ⅱ）。使用门控413-nm激发，时间分辨RR测量的溶解的感光体进行探测的光循环中间体，在亚毫秒的时间范围内形成。根据1568和1583 cm −1处的C=C伸缩带，首次确定了两个类M中间体，分别对应于早期的M（L）400态和随后的M（1）400态，前者的寿命为30μs，后者的寿命为2 ms。M（1）400异常高的C=C伸缩频率归因于在大部分疏水环境中未质子化的视黄酸席夫碱，这意味着M（L）400→ M（1）400跃迁与发色团结合口袋附近的蛋白质结构变化有关。NpSRII静电结合到旋转银电极上的时间分辨表面增强共振拉曼实验表明，光感受器也在固定状态下通过光循环。表面增强共振拉曼光谱是非常相似的RR光谱的溶解的蛋白质，排除了吸附诱导的结构变化的视网膜结合口袋。然而，光循环动力学敏感地受电极电位的影响，使得在0.0V（相对于Ag/AgCl）下，M（L）400和M（1）400的衰减时间显著减慢。当电位降低到−0.4V时，对应于界面电位降的降低，从而对应于蛋白质结合位点处的电场强度的降低，光循环动力学变得与溶液中的NpSRII相似。电场依赖性的蛋白质结构的变化与M-状态的转换，这在本光谱工作中揭示了在分子水平上，似乎是有关的电场控制细菌视紫红质的光循环，这已被证明是功能相关。
Sensory rhodopsin II (NpSRII) fromNatronobacterium pharaoniswas studied by resonance Raman (RR) spectroscopic techniques. Using gated 413-nm excitation, time-resolved RR measurements of the solubilized photoreceptor were carried out to probe the photocycle intermediates that are formed in the submillisecond time range. For the first time, two M-like intermediates were identified on the basis of their C=C stretching bands at 1568 and 1583cm−1, corresponding to the early M(L)400state with a lifetime of 30μs and the subsequent M(1)400state with a lifetime of 2ms, respectively. The unusually high C=C stretching frequency of M(1)400has been attributed to an unprotonated retinal Schiff base in a largely hydrophobic environment, implying that the M(L)400→ M(1)400transition is associated with protein structural changes in the vicinity of the chromophore binding pocket. Time-resolved surface enhanced resonance Raman experiments of NpSRII electrostatically bound onto a rotating Ag electrode reveal that the photoreceptor runs through the photocycle also in the immobilized state. Surface enhanced resonance Raman spectra are very similar to the RR spectra of the solubilized protein, ruling out adsorption-induced structural changes in the retinal binding pocket. The photocycle kinetics, however, is sensitively affected by the electrode potential such that at 0.0V (versus Ag/AgCl) the decay times of M(L)400and M(1)400are drastically slowed down. Upon decreasing the potential to −0.4V, that corresponds to a decrease of the interfacial potential drop and thus of the electric field strength at the protein binding site, the photocycle kinetics becomes similar to that of NpSRII in solution. The electric-field dependence of the protein structural changes associated with the M-state transitions, which in the present spectroscopic work is revealed on a molecular level, appears to be related to the electric-field control of bacteriorhodopsin's photocycle, which has been shown to be of functional relevance.
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影响因子：
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