Vibronic Dynamics of the Ultrafast all-trans to 13-cis Photoisomerization of Retinal in Channelrhodopsin-1

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• 作者：Christoph Schnedermann ; Vera Muders ; David Ehrenberg ; Ramona Schlesinger ; Philipp Kukura ; Joachim Heberle
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：April 13, 2016
• 年：2016
• 卷：138
• 期：14
• 页码：4757-4762
• 全文大小：413K
• 年卷期：0
• ISSN：1520-5126

文摘

Channelrhodopsins are light-gated ion channels with extensive applications in optogenetics. Channelrhodopsin-1 from Chlamydomonas augustae (CaChR1) exhibits a red-shifted absorption spectrum as compared to Channelrhodopsin-2, which is highly beneficial for optogenetic application. The primary event in the photocycle of CaChR1 involves an isomerization of the protein-bound retinal chromophore. Here, we apply highly time-resolved vibronic spectroscopy to reveal the electronic and structural dynamics associated with the first step of the photocycle of CaChR1. We observe vibrationally coherent formation of the P₁ intermediate exhibiting a twisted 13-cis retinal with a 110 ± 7 fs time constant. Comparison with low-temperature resonance Raman spectroscopy of the corresponding trapped photoproduct demonstrates that this rapidly formed P₁ intermediate is stable for several hundreds of nanoseconds.