title: Membrane Independence of Ultrafast Photochemistry in Pharaonis Halorhodopsin: Testing the Role of Bacterioruberin.
abstract: Ultrafast photochemistry of pharaonis halorhodopsin (p-HR) in the intact membrane of Natronomonas pharaonis has been studied by photoselective femtosecond pump-hyperspectral probe spectroscopy with high time resolution. Two variants of this sample were studied, one with wild-type retinal prosthetic groups and another after shifting the retinal absorption deep into the blue range by reducing the Schiff base linkage, and the results were compared to a previous study on detergent-solubilized p-HR. This comparison shows that retinal photoisomerization dynamics is identical in the membrane and in the solubilized sample. Selective photoexcitation of bacterioruberin, which is associated with the protein in the native membrane, in wild-type and reduced samples, demonstrates conclusively that unlike the carotenoids associated with some bacterial retinal proteins the carrotenoid in p-HR does not act as a light-harvesting antenna.
authors.affiliation: Institute of Chemistry, the Hebrew University , Jerusalem 91904, Israel.
authors.forename: Itay
authors.identifier: 0000-0002-5900-6082
authors.initials: I
authors.lastname: Gdor
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Maya
authors.initials: M
authors.lastname: Mani-Hazan
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Noga
authors.initials: N
authors.lastname: Friedman
authors.affiliation: Department of Organic Chemistry, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Mordechai
authors.initials: M
authors.lastname: Sheves
authors.affiliation: Institute of Chemistry, the Hebrew University , Jerusalem 91904, Israel.
authors.forename: Sanford
authors.initials: S
authors.lastname: Ruhman
mesh_terms: D002338:Carotenoids / Q000737:chemistry / Q000528:radiation effects*; D002462:Cell Membrane / Q000737:chemistry; D006216:Halobacteriaceae; D025602:Halorhodopsins / Q000737:chemistry / Q000528:radiation effects*; D008027:Light; D010777:Photochemistry; D012172:Retinaldehyde / Q000737:chemistry / Q000528:radiation effects
chemical_list: D025602:Halorhodopsins; C002951:bacterioruberin; D002338:Carotenoids; D012172:Retinaldehyde