Ultrafast Photochemical Reaction of Exiguobacterium sibiricum Rhodopsin (ESR) at Alkaline pH

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2024-08-05 DOI:10.1134/S1068162024040058

O. A. Smitienko, T. B. Feldman, L. E. Petrovskaya, E. A. Kryukova, I. V. Shelaev, F. E. Gostev, D. A. Cherepanov, I. B. Kolchugina, D. A. Dolgikh, V. A. Nadtochenko, M. P. Kirpichnikov, M. A. Ostrovsky

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Abstract

Objective: Rhodopsin from the eubacterium Exiguobacterium sibiricum (ESR) performs the lightdependent proton pumping function. The operation of ESR is based on the ultrafast photochemical reaction of isomerization of the retinal chromophore, which triggers dark processes closed in a photocycle. Many parameters of the photocycle are determined by the presence of a hydrogen bond between the primary counterion Asp85 and the chromophore. ESR in detergent micelles pumps protons most efficiently at pH > 9, when such a bond is most probable. Methods: In the present study, the photochemical reaction of ESR at pH 9.5 was investigated by femtosecond laser absorption spectroscopy. Results and Discussion: It was shown that photoisomerization of the chromophore group occurs in 0.51 ps, with the contribution from the reactive excited state being ca. 80%. A comparison with the earlier obtained data for pH 7.4 showed that, at pH 9.5, the reaction proceeds much faster and more efficiently. Conclusions: The present results confirm the important role of the chromophore group counterion in the photoactivated processes of rhodopsins.

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西西伯利亚外分支杆菌（ESR）在碱性 pH 下的超快光化学反应

摘要目的西西伯利亚外杆菌（ESR）的视紫红质（Rhodopsin）具有依赖光的质子泵功能。ESR 的运行基于视网膜发色团异构化的超快光化学反应，该反应引发了光周期中封闭的暗过程。光周期的许多参数取决于初级反离子 Asp85 和发色团之间是否存在氢键。洗涤剂胶束中的 ESR 在 pH 值为 9 时泵送质子的效率最高，因为此时最有可能出现这种键。方法：本研究采用飞秒激光吸收光谱法研究了 ESR 在 pH 值为 9.5 时的光化学反应。结果与讨论：研究表明，发色团基团在 0.51 ps 内发生光异构化，反应激发态的贡献率约为 80%。与之前获得的 pH 值为 7.4 的数据相比，pH 值为 9.5 时的反应速度更快，效率更高。结论本研究结果证实了发色团反离子在犀牛蛋白光激活过程中的重要作用。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.