A Nonadiabatic Ab Initio Dynamics Study on Rhodopsin and Its Analog Isorhodopsin: Chemical Dynamics Reasons behind Selection of Rhodopsin by Life

• Wilfredo Credo Chung

  Fukui Institute for Fundamental Chemistry, Kyoto University

• Shinkoh Nanbu

  Department of Materials and Life Sciences, Faculty of Science and Engineering, Sophia University

• Toshimasa Ishida

  Fukui Institute for Fundamental Chemistry, Kyoto University

Abstract

The structural difference between rhodopsin and isorhodopsin is only in the cis-position of the chromophore, but the difference leads to a large discrepancy in photoisomerization period and quantum yield. The photoinduced cis–trans isomerization dynamics of the two chromophores are investigated using a Quantum Mechanics/Molecular Mechanics trajectory surface hopping scheme. Rhodopsin shows a straightforward and fast excited-state dynamics whereas the isorhodopsin dynamics in the excited state is complicated due to differences in retinal motions and space gaps formed by surrounding residues. Consequently, the isorhodopsin → bathorhodopsin reaction is slower and less efficient. Photoexcitation of rhodopsin gives bathorhodopsin only, whereas isorhodopsin yields an analog with 9,11-di-cis-retinal in addition to bathorhodopsin. These differences explain why life uses rhodopsin rather than isorhodopsin.

Journal

• Chemistry Letters

  Chemistry Letters 40 (12), 1395-1397, 2011-11-26

  Oxford University Press (OUP)

Keywords

• General Chemistry

Details

• CRID: 1360565169064932864
• NII Article ID: 130004426120
• DOI: 10.1246/cl.2011.1395
• ISSN: 13480715
• ISSN: 03667022
• Web Site: https://academic.oup.com/chemlett/article-pdf/40/12/1395/55606367/cl.2011.1395.pdf
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