Quantum Mechanics/Molecular Mechanics Study on the Photoreactions of Dark- and Light-Adapted States of a Blue-Light YtvA LOV Photoreceptor
Quantum Mechanics/Molecular Mechanics Study on the Photoreactions of Dark- and Light-Adapted States of a Blue-Light YtvA LOV Photoreceptor
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DOI：
10.1002/anie.201703487
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发表时间：
2017-08-01
影响因子：
16.6
通讯作者：
Thiel, Walter
中科院分区：
文献类型：
--
作者：
Chang, Xue-Ping;Gao, Yuan-Jun;Thiel, Walter
YtvA LOV结构域的暗适应态和光适应态表现出不同的激发态行为。我们采用高阶QM(MS-CASPT2)/MM计算研究了暗态和光适应态的光化学反应。暗适应态的光反应开始于S-1 -> T-1系统间交叉，随后是三态氢从硫醇转移到黄素部分，产生双自由基中间体，随后的内部转化引发S-0态的无障碍C-S键形成。这些转换的能量分布对于所考虑的四种暗适应态的构象是不同的。光适应态的光化学不涉及三重态：光激发到S-1态触发C-S键裂解，然后在S-0态重组；这两种过程基本上都是无障碍的，因此是超快的。本研究为研究含黄素蓝光光感受器的光响应提供了新的机制。
The dark-and light-adapted states of YtvA LOV domains exhibit distinct excited-state behavior. We have employed high-level QM(MS-CASPT2)/MM calculations to study the photochemical reactions of the dark-and light-adapted states. The photoreaction from the dark-adapted state starts with an S-1 -> T-1 intersystem crossing followed by a triplet-state hydrogen transfer from the thiol to the flavin moiety that produces a diradical intermediate, and a subsequent internal conversion that triggers a barrierless C-S bond formation in the S-0 state. The energy profiles for these transformations are different for the four conformers of the dark-adapted state considered. The photochemistry of the light-adapted state does not involve the triplet state: photoexcitation to the S-1 state triggers C-S bond cleavage followed by recombination in the S-0 state; both these processes are essentially barrierless and thus ultrafast. The present work offers new mechanistic insights into the photoresponse of flavin-containing blue-light photoreceptors.