文章基本信息

标题：Revealing the origin of multiphasic dynamic behaviors in cyanobacteriochrome
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作者：Dihao Wang ; Xiankun Li ; Sheng Zhang 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：33
页码：19731-19736
DOI：10.1073/pnas.2001114117
出版社：The National Academy of Sciences of the United States of America
摘要：Cyanobacteriochromes are photoreceptors in cyanobacteria that exhibit a wide spectral coverage and unique photophysical properties from the photoinduced isomerization of a linear tetrapyrrole chromophore. Here, we integrate femtosecond-resolved fluorescence and transient-absorption methods and unambiguously showed the significant solvation dynamics occurring at the active site from a few to hundreds of picoseconds. These motions of local water molecules and polar side chains are continuously convoluted with the isomerization reaction, leading to a nonequilibrium processes with continuous active-site motions. By mutations of critical residues at the active site, the modified local structures become looser, resulting in faster solvation relaxations and isomerization reaction. The observation of solvation dynamics is significant and critical to the correct interpretation of often-observed multiphasic dynamic behaviors, and thus the previously invoked ground-state heterogeneity may not be relevant to the excited-state isomerization reaction.
关键词：active-site relaxation ; double-bond twisting ; conical intersection ; femtosecond spectroscopy ; site-directed mutation