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- Title
Triplet excited state spectra and dynamics of carotenoids from the thermophilic purple photosynthetic bacterium Thermochromatium tepidum.
- Authors
Niedzwiedzki, Dariusz M.; Kobayashi, Masayuki; Blankenship, Robert E.
- Abstract
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 Q 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.
- Subjects
PHOTOTROPISM; BACTERIA; FLUORESCENCE; PHOTOCHEMISTRY; SPECTRUM analysis; PLANTS
- Publication
Photosynthesis Research, 2011, Vol 107, Issue 2, p177
- ISSN
0166-8595
- Publication type
Article
- DOI
10.1007/s11120-011-9620-x