Nonisomerizable non-retinal chromophores initiate light-induced conformational alterations in bacterioopsin

A. Aharoni, L. Weiner, A. Lewis, M. Ottolenghi, M. Sheves

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The photoactivation of retinal proteins is usually interpreted in terms of C=C photoisomerization of the retinal moiety, which triggers appropriate conformational changes in the protein. In this work several dye molecules, characterized by a completely rigid structure in which no double-bond isomerization is possible, were incorporated into the binding site of bacteriorhodopsin (bR). Using a light-induced chemical reaction of a labeled EPR probe, it was observed that specific conformational alterations in the protein are induced following light absorption by the dye molecules occupying the binding site. The exact nature of these changes and their relationship to those occurring in the bR photocycle are still unclear. Nevertheless, their occurrence proves that C=C or C=NH+ isomerization is not a prerequisite for protein conformational changes in a retinal protein. More generally, we show that conformational changes, leading to changes in reactivity, may be induced in proteins by optical excitation of simple nonisomerizable dyes located in the macromolecular matrix.

Original languageEnglish
Pages (from-to)6612-6616
Number of pages5
JournalJournal of the American Chemical Society
Issue number27
StatePublished - 11 Oct 2001
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry


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