Time-Resolved Spectroscopy of Ultrafast Photoisomerization of Octopus Rhodopsin under Photoexcitation

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• 作者：Atsushi Yabushita ; Takayoshi Kobayashi ; Motoyuki Tsuda
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：February 16, 2012
• 年：2012
• 卷：116
• 期：6
• 页码：1920-1926
• 全文大小：408K
• 年卷期：v.116,no.6(February 16, 2012)
• ISSN：1520-5207

文摘

A primary process in vision is the cis鈥?i>trans photoisomerization of a chromophore of rhodopsin, called retinal. In the present work, we have performed ultrafast time-resolved spectroscopy of octopus rhodopsin using a sub-5-fs pulse laser. In comparison with our previous study on bacteriorhodopsin, we found that octopus rhodopsin follows similar dynamics after photoexcitation but with different time constants. Spectrogram analysis showed that a C鈺怤 stretching mode appeared directly after photoexcitation. After reaching the conical intersection region at 80 fs, the overlapping hydrogen out-of-plane and in-plane C鈺怌鈥揌 modes emerged as distinct peaks at 200 fs, finishing a rapid relaxation along the coordinate related with these modes. The intensities of these peaks and a C鈺怌 stretching mode were found to be modulated at a period of 500 fs, reflecting torsional motion around the C鈺怌 double bond before thermalization with the distribution of structural variations in the all-trans structure in configuration space.