Protein Dynamics Preceding Photoisomerization of the Retinal Chromophore in Bacteriorhodopsin Revealed by Deep-UV Femtosecond Stimulated Raman Spectroscopy

Shinya Tahara, Hikaru Kuramochi, Satoshi Takeuchi, Tahei Tahara

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

Bacteriorhodopsin is a prototypical photoreceptor protein that functions as a light-driven proton pump. The retinal chromophore of bacteriorhodopsin undergoes C13=C14 trans-to-cis isomerization upon photoexcitation, and it has been believed to be the first event that triggers the cascaded structural changes in bacteriorhodopsin. We investigated the protein dynamics of bacteriorhodopsin using deep-ultraviolet resonance femtosecond stimulated Raman spectroscopy. It was found that the stimulated Raman signals of tryptophan and tyrosine residues exhibit significant changes within 0.2 ps after photoexcitation while they do not noticeably change during the isomerization process. This result implies that the protein environment changes first, and its change is small during isomerization. The obtained femtosecond stimulated Raman data indicate that ultrafast change is induced in the protein part by the sudden creation of the large dipole of the excited-state chromophore, providing an environment that realizes efficient and selective isomerization.

Original languageEnglish
Pages (from-to)5422-5427
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume10
Issue number18
DOIs
Publication statusPublished - 2019 Sep 19
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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