title: Red chlorophyll excitation dynamics in Arthrospira platensis photosystem I trimeric complexes as studied by femtosecond transient absorption spectroscopy.
abstract: Femtosecond absorption spectroscopy was applied to study for the first time excitation dynamics in isolated photosystem I trimers from Arthrospira platensis, which display extremely long-wavelength absorption peaks. Pump-probe spectra observed at 77K in the timescale of dozens of picoseconds upon 70-fs excitation revealed two maxima near 710 and 730 nm, which correspond to red chlorophyll forms. Bleaching at 680 nm developed in ∼ 200 fs, whereas the bleaching kinetics at 710 and 730 nm exhibited two components with time constants of 1 and 5.5 ps. Comparison of the kinetics of bleaching development at 710 nm and 730 nm with that of bleaching decay at 680 nm indicated that both long-wavelength forms of trimers are populated mainly via direct energy transfer from bulk chlorophyll.
authors.affiliation: Institute of Spectroscopy RAS, 142190 Troitsk, Moscow Region, Russia.
authors.forename: Viktor
authors.initials: V
authors.lastname: Kompanets
authors.affiliation: A.N. Bach Institute of Biochemistry RAS, 119071 Moscow, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shubin
authors.affiliation: A.N. Bach Institute of Biochemistry RAS, 119071 Moscow, Russia.
authors.forename: Irina
authors.initials: I
authors.lastname: Terekhova
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Elena
authors.initials: E
authors.lastname: Kotova
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Kozlovsky
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Novoderezhkin
authors.affiliation: Institute of Spectroscopy RAS, 142190 Troitsk, Moscow Region, Russia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Chekalin
authors.affiliation: A.N. Bach Institute of Biochemistry RAS, 119071 Moscow, Russia.
authors.forename: Navasard
authors.initials: N
authors.lastname: Karapetyan
authors.affiliation: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia.
authors.forename: Andrei
authors.initials: A
authors.lastname: Razjivin
mesh_terms: D001429:Bacteriochlorophylls / Q000737:chemistry*; D000458:Cyanobacteria; D004735:Energy Transfer; D007700:Kinetics; D045331:Photosystem I Protein Complex / Q000737:chemistry*; D013053:Spectrophotometry
chemical_list: D001429:Bacteriochlorophylls; D045331:Photosystem I Protein Complex
keywords: Arthrospira platensis; Femtosecond pump–probe spectroscopy; Long-wavelength red chlorophyll form; Photosystem I trimer