Emanuel Institute of Biochemical Physics of the Russian Academy of Sciences, Kosygin St., 4, Moscow 119334, Russia.
Department of Biology, Lomonosov Moscow State University, Leninskie Gory, 1, Moscow 119991, Russia.
Molecules. 2024 Oct 13;29(20):4847. doi: 10.3390/molecules29204847.
The operation of bacteriorhodopsin () from the archaeon is based on the photochromic reaction of isomerization of the chromophore group (the retinal protonated Schiff base, RPSB) from the all- to the 13- form. The ultrafast dynamics of the reverse 13- → all- photoreaction was studied using femtosecond transient absorption spectroscopy in comparison with the forward photoreaction. The forward photoreaction was initiated by photoexcitation of by pulse I (540 nm). The reverse photoreaction was initiated by photoexcitation of the product at an early stage of its formation (5 ps) by pulse II (660 nm). The conversion of the excited to the ground state proceeds at times of 0.19, 1.1, and 16 ps with the relative contributions of ~20/60/20, respectively. All these decay channels lead to the formation of the initial state of as a product with a quantum yield of ~1. This state is preceded by vibrationally excited intermediates, the relaxation of which occurs in the 16 ps time range. Likely, the heterogeneity of the excited state of is determined by the heterogeneity of its chromophore center. The forward photoreaction includes two components-0.52 and 3.5 ps, with the relative contributions of 91/9, respectively. The reverse photoreaction initiated from proceeds more efficiently in the conical intersection (CI) region but on the whole at a lower rate compared to the forward photoreaction, due to significant heterogeneity of the potential energy surface.
嗜盐菌视紫红质（）的作用机制基于发色团（质子化视黄醛 Schiff 碱，RPSB）从全-到 13-形式的光致异构化的光致变色反应。与正向光反应相比，使用飞秒瞬态吸收光谱法研究了反向 13-→全-光致反应的超快动力学。正向光反应由脉冲 I（540nm）激发来引发。反向光反应由脉冲 II（660nm）在其形成的早期阶段（5ps）激发产物 来引发。激发的 向基态的转化在 0.19、1.1 和 16ps 的时间内进行，相对贡献分别约为 20/60/20。所有这些衰减通道都导致作为产物的 的初始状态的形成，其量子产率约为 1。该状态之前是振动激发的中间体，其弛豫发生在 16ps 的时间范围内。可能，的激发态的不均匀性由其发色团中心的不均匀性决定。正向光反应包括两个分量-0.52 和 3.5ps，相对贡献分别为 91/9。从 引发的反向光反应在锥形交叉（CI）区域中更有效地进行，但由于势能面的显著不均匀性，其整体速率比正向光反应低。
