title: Energy transfer in the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, analyzed by time-resolved fluorescence spectroscopies.
abstract: We prepared thylakoid membranes from Halomicronema hongdechloris cells grown under white fluorescent light or light from far-red (740 nm) light-emitting diodes, and observed their energy-transfer processes shortly after light excitation. Excitation-relaxation processes were examined by steady-state and time-resolved fluorescence spectroscopies. Two time-resolved fluorescence techniques were used: time-correlated single photon counting and fluorescence up-conversion methods. The thylakoids from the cells grown under white light contained chlorophyll (Chl) a of different energies, but were devoid of Chl f. At room temperature, the excitation energy was equilibrated among the Chl a pools with a time constant of 6.6 ps. Conversely, the thylakoids from the cells grown under far-red light possessed both Chl a and Chl f. Two energy-transfer pathways from Chl a to Chl f were identified with time constants of 1.3 and 5.0 ps, and the excitation energy was equilibrated between the Chl a and Chl f pools at room temperature. We also examined the energy-transfer pathways from phycobilisome to the two photosystems under white-light cultivation.
authors: Molecular Photoscience Research Center, Kobe University, Kobe, 657-8501, Japan, akimoto@hawk.kobe-u.ac.jp.
authors: Seiji
authors: S
authors: Akimoto
authors: Toshiyuki
authors: T
authors: Shinoda
authors: Min
authors: M
authors: Chen
authors: Suleyman I
authors: SI
authors: Allakhverdiev
authors: Tatsuya
authors: T
authors: Tomo
mesh_terms: D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000378:metabolism; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000378:metabolism*; D004735:Energy Transfer; D005453:Fluorescence; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D045524:Phycobilisomes / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D020524:Thylakoids / Q000378:metabolism
chemical_list: D045342:Light-Harvesting Protein Complexes; D045524:Phycobilisomes; C583352:chlorophyll f; D002734:Chlorophyll; C085815:chlorophyll a'; D000077194:Chlorophyll A
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