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Molecular Mechanism of Flavin Photoprotection by Archaeal Dodecin: Photoinduced Electron Transfer and Mg2+-Promoted Proton Transfer
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2017-11-08 00:00:00 , DOI: 10.1021/acs.jpcb.7b08597
Maximilian Scheurer 1 , Daria Brisker-Klaiman 1 , Andreas Dreuw 1
Affiliation  

Photoinduced biochemical reactions are ubiquitously governed by derivatives of flavin, which is a key player in a manifold of cellular redox reactions. The photoreactivity of flavins is also one of their greatest disadvantages as the molecules are sensitive to photodegradation. To prevent this unfavorable reaction, UV-light-exposed archaea bacteria, such as Halobacterium salinarum, manage the task of protecting flavin derivatives by dodecin, a protein which stores flavins and efficiently photoprotects them. In this study, we shed light on the photoprotection mechanism, i.e., the excited state quenching mechanism by dodecin using computational methodology. Molecular dynamics (MD) simulations unraveled the hydrogen bond network in the flavin binding pocket as a starting point for proton transfer upon preceding electron transfer. Using high-level ab initio quantum chemical methods, different proton transfer channels have been investigated and an energetically feasible Mg2+-promoted channel has been identified fully explaining previous experimental observations. This is the first extensive theoretical study of archaeal dodecin, furthering the understanding of its photocycle and manipulation.

中文翻译:

古代十二烷对黄素进行光保护的分子机理:光诱导电子转移和Mg 2+促进质子转移

黄素的衍生物无处不在地控制着光诱导的生化反应,黄素的衍生物是细胞氧化还原反应的重要组成部分。黄素的光反应性也是它们最大的缺点之一,因为该分子对光降解敏感。为了防止这种不利的反应,应使用暴露于紫外线下的古细菌,如盐杆菌(Halobacterium salinarum)负责通过十二烷来保护黄素衍生物的任务,十二蛋白是一种存储黄素并有效地对其进行光保护的蛋白质。在这项研究中,我们用计算方法阐明了光敏保护机理,即十二碳烯的激发态猝灭机理。分子动力学(MD)模拟揭示了黄素键合口袋中的氢键网络,以此作为质子在先前电子转移时转移的起点。使用高级从头算术量子化学方法,已经研究了不同的质子传递通道,并且在能量上可行的Mg 2+促进的通道已被确定,充分解释了先前的实验观察结果。这是首次对古细菌十二烷进行广泛的理论研究,进一步加深了对它的光周期和操纵的了解。
更新日期:2017-11-09
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