title: Multichannel carotenoid deactivation in photosynthetic light harvesting as identified by an evolutionary target analysis.
abstract: A new channel of excitation energy deactivation in bacterial light harvesting was recently discovered, which leads to carotenoid triplet population on an ultrafast timescale. Here we show that this mechanism is also active in LH2 of Rhodopseudomonas acidophila through analysis of transient absorption data with an evolutionary target analysis. The algorithm offers flexible testing of kinetic network models with low a priori knowledge requirements. It applies universally to the simultaneous fitting of target state spectra and rate constants to time-wavelength-resolved data. Our best-fit model reproduces correctly the well-known cooling and decay behavior in the S(1) band, but necessitates an additional, clearly distinct singlet state that does not exchange with S(1), promotes ultrafast triplet population and participates in photosynthetic energy transfer.
authors.affiliation: Max-Planck-Institut für Quantenoptik, Garching, Germany.
authors.forename: Wendel
authors.initials: W
authors.lastname: Wohlleben
authors.forename: Tiago
authors.initials: T
authors.lastname: Buckup
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Herek
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Cogdell
authors.forename: Marcus
authors.initials: M
authors.lastname: Motzkus
mesh_terms: D000465:Algorithms; D002338:Carotenoids / Q000737:chemistry* / Q000528:radiation effects*; D003198:Computer Simulation; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000528:radiation effects*; D008956:Models, Chemical; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000528:radiation effects*; D012241:Rhodopseudomonas / Q000737:chemistry* / Q000145:classification; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D002338:Carotenoids