title: Energy transfer processes in the isolated core antenna complexes CP43 and CP47 of photosystem II.
abstract: The energy equilibration and transfer processes in the isolated core antenna complexes CP43 and CP47 of photosystem II have been studied by steady-state and ultrafast (femto- to nanosecond) time-resolved spectroscopy at room temperature. The annihilation-free femtosecond absorption data can be described by surprisingly simple sequential kinetic models, in which the excitation energy transfer between blue and red states in both antenna complexes is dominated by sub-picosecond processes and is completed in less than 2ps. The slowest energy transfer steps with lifetimes in the range of 1-2ps are assigned to transfer steps between the chlorophyll layers located on the stromal and lumenal sides. We conclude that these ultrafast intra-antenna energy transfer steps do not represent a bottleneck in the rate of the primary processes in intact photosystem II. Since the experimental energy equilibration rates are up to a factor of 3-5 higher than concluded previously, our results challenge the conclusions drawn from theoretical modeling.
authors.affiliation: CNR-Istituto di Biofisica, Dipartimento di Biologia, Universita; degli Studi di Milano, Milan, Italy.
authors.forename: Anna Paola
authors.initials: AP
authors.lastname: Casazza
authors.forename: Malwina
authors.initials: M
authors.lastname: Szczepaniak
authors.forename: Marc G
authors.initials: MG
authors.lastname: Müller
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Zucchelli
authors.forename: Alfred R
authors.initials: AR
authors.lastname: Holzwarth
mesh_terms: D004735:Energy Transfer; D005453:Fluorescence; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D003313:Zea mays / Q000201:enzymology*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; C083100:photosystem II, chlorophyll binding protein, CP-43; C070970:photosystem II, chlorophyll-binding protein, CP-47