Institute of Chemistry and the Farkas Center for Light Induced Processes, The Hebrew University, Jerusalem 91904, Israel.
J Phys Chem B. 2010 Mar 4;114(8):3046-51. doi: 10.1021/jp910853n.
The primary photochemical dynamics of Hb. pharaonis Halorhodopsin (pHR) are investigated by femtosecond visible pump-near IR dump-hyperspectral probe spectroscopy. The efficiency of excited state depletion is deduced from transient changes in absorption, recorded with and without stimulated emission pumping (SEP), as a function of the dump delay. The concomitant reduction of photocycle population is assessed by probing the "K" intermediate difference spectrum. Results show that the cross section for stimulating emission is nearly constant throughout the fluorescent state lifetime. Probing "K" demonstrates that dumping produces a proportionate reduction in photocycle yields. We conclude that, despite its nonexponential internal conversion (IC) kinetics, the fluorescent state in pHR constitutes a single intermediate in the photocycle. This contrasts with conclusions drawn from the study of primary events in the related chloride pump from Hb. salinarum (sHR), believed to produce the "K" intermediate from a distinct short-lived subpopulation in the excited state. Our discoveries concerning internal conversion dynamics in pHR are discussed in light of recent expectations for similar excited state dynamics in both proteins.
通过飞秒可见泵近红外转储高光谱探针光谱法研究了 Hb. pharaonis 盐红视蛋白（pHR）的主要光化学动力学。通过记录有无受激发射泵浦（SEP）的情况下的吸收瞬态变化，从激发态消耗的效率作为转储延迟的函数推导出来。通过探测“K”中间体差谱评估光循环种群的伴随减少。结果表明，在荧光状态寿命内，刺激发射的截面几乎保持不变。探测“K”表明转储会导致光循环产率成比例减少。我们得出结论，尽管 pHR 中的内部转换（IC）动力学是非指数的，但荧光态在光循环中构成单个中间体。这与从 Hb. salinarum（sHR）相关氯泵中初级事件研究得出的结论形成对比，据信 sHR 从激发态中的独特短寿命亚群产生“K”中间体。我们对 pHR 中内部转换动力学的发现，根据这两种蛋白质中类似激发态动力学的最新预期进行了讨论。
