Time-resolved spectroscopy of ultrafast photoisomerization of octopus rhodopsin under photoexcitation

Atsushi Yabushita*, Takayoshi Kobayashi, Motoyuki Tsuda

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

A primary process in vision is the cis-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-N 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-C-H 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-C stretching mode were found to be modulated at a period of ∼500 fs, reflecting torsional motion around the C-C double bond before thermalization with the distribution of structural variations in the all-trans structure in configuration space.

Original languageEnglish
Pages (from-to)1920-1926
Number of pages7
JournalJournal of Physical Chemistry B
Volume116
Issue number6
DOIs
StatePublished - 17 Jan 2012

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