Photoprotection Mechanism of Light-Harvesting Antenna Complex from Purple Bacteria

Photosynthetic light-harvesting apparatus efficiently capture sunlight and transfer the energy to reaction centers, while they safely dissipate excess energy to surrounding environments for a protection of their organisms. In this study, we performed pump–probe spectroscopic measurements with a temp...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2016-02, Vol.120 (5), p.951-956
Main Authors: Kosumi, Daisuke, Horibe, Tomoko, Sugisaki, Mitsuru, Cogdell, Richard J, Hashimoto, Hideki
Format: Article
Language:English
Subjects:
Antennas
Assembly
Bacteria
Carotenoids
Energy transfer
Excitation
Femtosecond
Light
Light-Harvesting Protein Complexes - metabolism
Photosynthesis
Proteobacteria - metabolism
Rhodobacter sphaeroides - metabolism
solar (fuels), photosynthesis (natural and artificial), biofuels (including algae and biomass), bio-inspired, charge transport, membrane, synthesis (novel materials), synthesis (self-assembly)
Spectroscopy
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Summary:Photosynthetic light-harvesting apparatus efficiently capture sunlight and transfer the energy to reaction centers, while they safely dissipate excess energy to surrounding environments for a protection of their organisms. In this study, we performed pump–probe spectroscopic measurements with a temporal window ranging from femtosecond to submillisecond on the purple bacterial antenna complex LH2 from Rhodobacter sphaeroides 2.4.1 to clarify its photoprotection functions. The observed excited state dynamics in the time range from subnanosecond to microsecond exhibits that the triplet–triplet excitation energy transfer from bacteriochlorophyll a to carotenoid takes place with a time constant of 16.7 ns. Furthermore, ultrafast spectroscopic data suggests that a molecular assembly of bacteriochlorophyll a in LH2 efficiently suppresses a generation of triple bacteriochlorophyll a.
ISSN:1520-6106
1520-5207
DOI:10.1021/acs.jpcb.6b00121