caa a22 4500 445889837 CHVBK 20180317145612.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s11120-011-9620-x doi (NATIONALLICENCE)springer-10.1007/s11120-011-9620-x Triplet excited state spectra and dynamics of carotenoids from the thermophilic purple photosynthetic bacterium Thermochromatium tepidum [Elektronische Daten] [Dariusz Niedzwiedzki, Masayuki Kobayashi, Robert Blankenship] Light-harvesting complex 2 from the anoxygenic phototrophic purple bacterium Thermochromatium tepidum was purified and studied by steady-state absorption, fluorescence and flash photolysis spectroscopy. Steady-state absorption and fluorescence measurements show that carotenoids play a negligible role as supportive energy donors and transfer excitation to bacteriochlorophyll-a with low energy transfer efficiency of ~30%. HPLC analysis determined that the dominant carotenoids in the complex are rhodopin and spirilloxanthin. Carotenoid excited triplet state formation upon direct (carotenoid) or indirect (bacteriochlorophyll-a Qx band) excitation shows that carotenoid triplets are mostly localized on spirilloxanthin. In addition, no triplet excitation transfer between carotenoids was observed. Such specific carotenoid composition and spectroscopic results strongly suggest that this organism optimized carotenoid composition in the light-harvesting complex 2 in order to maximize photoprotective capabilities of carotenoids but subsequently drastically suppressed their supporting role in light-harvesting process. Springer Science+Business Media B.V., 2011 Flash photolysis nationallicence Triplet state lifetime nationallicence Carotenoids nationallicence Light-harvesting complex nationallicence Car : Carotenoid nationallicence Rd : Rhodopin nationallicence Spx : Spirilloxanthin nationallicence BChl : Bacteriochlorophyll a nationallicence RT : Room temperature nationallicence DDM : n-Dodecyl-beta-d-maltoside nationallicence TA : Transient absorption nationallicence LH : Light-harvesting complex nationallicence T-S : Triplet-minus-singlet nationallicence ICM : Intracytoplasmic membrane nationallicence RC : Reaction center nationallicence Niedzwiedzki Dariusz Department of Biology, Washington University in St. Louis, 63130, St. Louis, MO, USA aut Kobayashi Masayuki Department of Material Science and Chemical Engineering, Ariake National College of Technology, 150 Higashihagio-machi, 836-8585, Omuta, Fukuoka, Japan aut Blankenship Robert Department of Biology, Washington University in St. Louis, 63130, St. Louis, MO, USA aut Photosynthesis Research Springer Netherlands 107/2(2011-02-01), 177-186 0166-8595 107:2<177 2011 107 11120 https://doi.org/10.1007/s11120-011-9620-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11120-011-9620-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Niedzwiedzki Dariusz Department of Biology, Washington University in St. Louis, 63130, St. Louis, MO, USA aut NATIONALLICENCE 700 1- Kobayashi Masayuki Department of Material Science and Chemical Engineering, Ariake National College of Technology, 150 Higashihagio-machi, 836-8585, Omuta, Fukuoka, Japan aut NATIONALLICENCE 700 1- Blankenship Robert Department of Biology, Washington University in St. Louis, 63130, St. Louis, MO, USA aut NATIONALLICENCE 773 0- Photosynthesis Research Springer Netherlands 107/2(2011-02-01), 177-186 0166-8595 107:2<177 2011 107 11120 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer