title: Triplet-triplet energy transfer from chlorophylls to carotenoids in two antenna complexes from dinoflagellate Amphidinium carterae.
abstract: Room temperature transient absorption spectroscopy with nanosecond resolution was used to study quenching of the chlorophyll triplet states by carotenoids in two light-harvesting complexes of the dinoflagellate Amphidinium carterae: the water soluble peridinin-chlorophyll protein complex and intrinsic, membrane chlorophyll a-chlorophyll c2-peridinin protein complex. The combined study of the two complexes facilitated interpretation of a rather complicated relaxation observed in the intrinsic complex. While a single carotenoid triplet state was resolved in the peridinin-chlorophyll protein complex, evidence of at least two different carotenoid triplets was obtained for the intrinsic light-harvesting complex. Most probably, each of these carotenoids protects different chlorophylls. In both complexes the quenching of the chlorophyll triplet states by carotenoids occurs with a very high efficiency (~100%), and with transfer times estimated to be in the order of 0.1ns or even faster. The triplet-triplet energy transfer is thus much faster than formation of the chlorophyll triplet states by intersystem crossing. Since the triplet states of chlorophylls are formed during the whole lifetime of their singlet states, the apparent lifetimes of both states are the same, and observed to be equal to the carotenoid triplet state rise time (~5ns).
authors.affiliation: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Prague CZ-12116, Czech Republic.
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Kvíčalová
authors.affiliation: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Prague CZ-12116, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Alster
authors.affiliation: Biophysics, Department of Biology and Biotechnology, Ruhr-University Bochum, D-44780 Bochum, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Hofmann
authors.affiliation: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Prague CZ-12116, Czech Republic.
authors.forename: Petro
authors.initials: P
authors.lastname: Khoroshyy
authors.affiliation: Biological Centre, Czech Academy of Sciences, České Budějovice CZ-37005, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice CZ-37005, Czech Republic.
authors.forename: Radek
authors.initials: R
authors.lastname: Litvín
authors.affiliation: Biological Centre, Czech Academy of Sciences, České Budějovice CZ-37005, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice CZ-37005, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Bína
authors.affiliation: Biological Centre, Czech Academy of Sciences, České Budějovice CZ-37005, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice CZ-37005, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Polívka
authors.affiliation: Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Prague CZ-12116, Czech Republic. Electronic address: psencik@karlov.mff.cuni.cz.
authors.forename: Jakub
authors.initials: J
authors.lastname: Pšenčík
mesh_terms: D000693:Anaerobiosis; D002338:Carotenoids / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry*; D004141:Dinoflagellida / Q000378:metabolism*; D004735:Energy Transfer; D015800:Protozoan Proteins / Q000737:chemistry*
chemical_list: D015800:Protozoan Proteins; C073227:peridinin chlorophyll-a protein, Dinophyceae; D002734:Chlorophyll; D002338:Carotenoids
keywords: Carotenoid; Chlorophyll; Dinoflagellate; Triplet state