Photochemistry of visual pigment chromophore models by ab initio molecular dynamics

Oliver Weingart, Igor Schapiro, Volker Buss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


Ab initio excited-state molecular dynamics calculations have been performed to study the effect of methyl substitution and chromophore distortion on the photoreaction of different four-double-bond retinal model chromophores. Randomly distributed starting geometries were generated by zero-point energy sampling; after Franck-Condon excitation the reaction was followed on the Si surface. For determining the photoproduct and its configuration, a simplified approach - torsion angle following-is discussed and applied. We find that chromophore distortion significantly affects the outcome of the photoreaction: with dihedral angles taken from the rhodopsin-embedded 11-cis-retinal chromophore, the reaction rate of the model chromophore is increased by a factor of 3 compared to that of the relaxed chromophore. Also, the reaction proceeds in a completely stereoselective manner involving only the cis double bond and with a minimum quantum yield of 72%. Bond torsion is more effective than methyl substitution for fast and selective photochemistry, which is in agreement with photophysical measurements on rhodopsin analogues. We conclude that apart from the geometric distortions caused by the protein pocket it is not necessary to postulate other specific interactions between the protein and the chromophore to effect the selective and ultrafast photoreaction in rhodopsin.

Original languageAmerican English
Pages (from-to)3782-3788
Number of pages7
JournalJournal of Physical Chemistry B
Issue number14
StatePublished - 12 Apr 2007
Externally publishedYes


Dive into the research topics of 'Photochemistry of visual pigment chromophore models by ab initio molecular dynamics'. Together they form a unique fingerprint.

Cite this