title: Efficient energy transfer from the carotenoid S(2) state in a photosynthetic light-harvesting complex.
abstract: Previously, the spatial arrangement of the carotenoid and bacteriochlorophyll molecules in the peripheral light-harvesting (LH2) complex from Rhodopseudomonas acidophila strain 10050 has been determined at high resolution. Here, we have time resolved the energy transfer steps that occur between the carotenoid's initial excited state and the lowest energy group of bacteriochlorophyll molecules in LH2. These kinetic data, together with the existing structural information, lay the foundation for understanding the detailed mechanisms of energy transfer involved in this fundamental, early reaction in photosynthesis. Remarkably, energy transfer from the rhodopin glucoside S(2) state, which has an intrinsic lifetime of approximately 120 fs, is by far the dominant pathway, with only a minor contribution from the longer-lived S(1) state.
authors.affiliation: Department of Biophysical Chemistry, Umeå University, SE-90187 Umeå, Sweden. Alisdair.Mcpherson@chem.umu.se
authors.forename: A N
authors.initials: AN
authors.lastname: Macpherson
authors.forename: J B
authors.initials: JB
authors.lastname: Arellano
authors.forename: N J
authors.initials: NJ
authors.lastname: Fraser
authors.forename: R J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: T
authors.initials: T
authors.lastname: Gillbro
mesh_terms: D001429:Bacteriochlorophylls / Q000737:chemistry; D055592:Biophysical Phenomena; D001703:Biophysics; D002338:Carotenoids / Q000737:chemistry*; D004735:Energy Transfer; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D012241:Rhodopseudomonas / Q000737:chemistry; D013053:Spectrophotometry
chemical_list: D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D002338:Carotenoids