title: Excitation energy transfer from the bacteriochlorophyll Soret band to carotenoids in the LH2 light-harvesting complex from Ectothiorhodospira haloalkaliphila is negligible.
abstract: Pathways of intramolecular conversion and intermolecular electronic excitation energy transfer (EET) in the photosynthetic apparatus of purple bacteria remain subject to debate. Here we experimentally tested the possibility of EET from the bacteriochlorophyll (BChl) Soret band to the singlet S2level of carotenoids using femtosecond pump-probe measurements and steady-state fluorescence excitation and absorption measurements in the near-ultraviolet and visible spectral ranges. The efficiency of EET from the Soret band of BChl to S2of the carotenoids in light-harvesting complex LH2 from the purple bacterium Ectothiorhodospira haloalkaliphila appeared not to exceed a few percent.
authors.affiliation: Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119991. razjivin@belozersky.msu.ru.
authors.forename: A P
authors.identifier: http://orcid.org/0000-0003-0957-5292
authors.initials: AP
authors.lastname: Razjivin
authors.affiliation: Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119991.
authors.forename: E P
authors.initials: EP
authors.lastname: Lukashev
authors.affiliation: Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, Russia, 142190.
authors.forename: V O
authors.initials: VO
authors.lastname: Kompanets
authors.affiliation: Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia, 119991.
authors.forename: V S
authors.initials: VS
authors.lastname: Kozlovsky
authors.affiliation: Institute of Fundamental Problems of Biology, Russian Academy of Sciences, Pushchino, Moscow Region, Russia, 142290.
authors.forename: A A
authors.identifier: http://orcid.org/0000-0001-6978-8017
authors.initials: AA
authors.lastname: Ashikhmin
authors.affiliation: Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow, Russia, 142190.
authors.forename: S V
authors.initials: SV
authors.lastname: Chekalin
authors.affiliation: Institute of Fundamental Problems of Biology, Russian Academy of Sciences, Pushchino, Moscow Region, Russia, 142290.
authors.forename: A A
authors.initials: AA
authors.lastname: Moskalenko
authors.affiliation: Faculty of Biology, Lomonosov Moscow State University, Moscow, Russia, 119991.
authors.forename: V Z
authors.initials: VZ
authors.lastname: Paschenko
mesh_terms: D001429:Bacteriochlorophylls / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism*; D020587:Ectothiorhodospira / Q000378:metabolism*; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D002338:Carotenoids
keywords: Bacteriochlorophyll; Carotenoids; Ectothiorhodospira haloalkaliphila; Excitation energy transfer; LH2; Soret band