title: Comparison of the fluorescence kinetics of detergent-solubilized and membrane-reconstituted LH2 complexes from Rps. acidophila and Rb. sphaeroides.
abstract: Picosecond time-resolved fluorescence spectroscopy has been used in order to compare the fluorescence kinetics of detergent-solubilized and membrane-reconstituted light-harvesting 2 (LH2) complexes from the purple bacteria Rhodopseudomonas (Rps.) acidophila and Rhodobacter (Rb.) sphaeroides. LH2 complexes were reconstituted in phospholipid model membranes at different lipid:protein-ratios and all samples were studied exciting with a wide range of excitation densities. While the detergent-solubilized LH2 complexes from Rps. acidophila showed monoexponential decay kinetics (tau(f )= 980 ps) for excitation densities of up to 3.10(13) photons/(pulse.cm(2)), the membrane-reconstituted LH2 complexes showed multiexponential kinetics even at low excitation densities and high lipid:protein-ratios. The latter finding indicates an efficient clustering of LH2 complexes in the phospholipid membranes. Similar results were obtained for the LH2 complexes from Rb. sphaeroides.
authors.affiliation: Lehrstuhl für Experimentalphysik IV, Universität Bayreuth, Universtitätsstrasse 30, 95440, Bayreuth, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Pflock
authors.forename: Manuela
authors.initials: M
authors.lastname: Dezi
authors.forename: Giovanni
authors.initials: G
authors.lastname: Venturoli
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: Jürgen
authors.initials: J
authors.lastname: Köhler
authors.forename: Silke
authors.initials: S
authors.lastname: Oellerich
mesh_terms: D003902:Detergents / Q000737:chemistry*; D005453:Fluorescence; D007700:Kinetics; D012242:Rhodobacter sphaeroides / Q000737:chemistry*; D012241:Rhodopseudomonas / Q000737:chemistry*; D012995:Solubility
chemical_list: D003902:Detergents