title: Optical spectroscopic studies of light-harvesting by pigment-reconstituted peridinin-chlorophyll-proteins at cryogenic temperatures.
abstract: Low temperature, steady-state, optical spectroscopic methods were used to study the spectral features of peridinin-chlorophyll-protein (PCP) complexes in which recombinant apoprotein has been refolded in the presence of peridinin and either chlorophyll a (Chl a), chlorophyll b (Chl b), chlorophyll d (Chl d), 3-acetyl-chlorophyll a (3-acetyl-Chl a) or bacteriochlorophyll a (BChl a). Absorption spectra taken at 10 K provide better resolution of the spectroscopic bands than seen at room temperature and reveal specific pigment-protein interactions responsible for the positions of the Qy bands of the chlorophylls. The study reveals that the functional groups attached to Ring I of the two protein-bound chlorophylls modulate the Qy and Soret transition energies. Fluorescence excitation spectra were used to compute energy transfer efficiencies of the various complexes at room temperature and these were correlated with previously reported ultrafast, time-resolved optical spectroscopic dynamics data. The results illustrate the robust nature and value of the PCP complex, which maintains a high efficiency of antenna function even in the presence of non-native chlorophyll species, as an effective tool for elucidating the molecular details of photosynthetic light-harvesting.
authors.affiliation: Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060 USA.
authors.forename: Robielyn P
authors.initials: RP
authors.lastname: Ilagan
authors.forename: Timothy W
authors.initials: TW
authors.lastname: Chapp
authors.forename: Roger G
authors.initials: RG
authors.lastname: Hiller
authors.forename: Frank P
authors.initials: FP
authors.lastname: Sharples
authors.forename: Tomás
authors.initials: T
authors.lastname: Polívka
authors.forename: Harry A
authors.initials: HA
authors.lastname: Frank
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology; D002338:Carotenoids / Q000737:chemistry / Q000502:physiology*; D002734:Chlorophyll / Q000737:chemistry / Q000502:physiology*; D056890:Eukaryota; D005615:Freezing; D008027:Light; D008958:Models, Molecular; D010940:Plant Proteins / Q000737:chemistry / Q000502:physiology*; D011487:Protein Conformation; D015800:Protozoan Proteins / Q000737:chemistry / Q000502:physiology*; D013053:Spectrophotometry
chemical_list: D001426:Bacterial Proteins; D010940:Plant Proteins; D015800:Protozoan Proteins; D002734:Chlorophyll; C016040:peridinin; D002338:Carotenoids