title: Ultrafast excitation dynamics of low energy pigments in reconstituted peripheral light-harvesting complexes of photosystem I.
abstract: Ultrafast dynamics of a reconstituted Lhca4 subunit from the peripheral LHCI-730 antenna of photosystem I of higher plants were probed by femtosecond absorption spectroscopy at 77 K. Intramonomeric energy transfer from chlorophyll (Chl) b to Chl a and energy equilibration between Chl a molecules observed on the subpicosecond time scale are largely similar to subpicosecond energy equilibration processes within LHCII monomers. However, a 5 ps equilibration process in Lhca4 involves unique low energy Chls in LHCI absorbing at 705 nm. These pigments localize the excitation both in the Lhca4 subunit and in LHCI-730 heterodimers. An additional 30-50 ps equilibration process involving red pigments of Lhca4 in the heterodimer, observed by transient absorption and picosecond fluorescence spectroscopy, was ascribed to intersubunit energy transfer.
authors.affiliation: Department of Chemistry and Biochemistry and Center for the Study of Early Events in Photosynthesis, Arizona State University, Tempe, AZ 85287-1604, USA.
authors.forename: A N
authors.initials: AN
authors.lastname: Melkozernov
authors.forename: S
authors.initials: S
authors.lastname: Lin
authors.forename: V H
authors.initials: VH
authors.lastname: Schmid
authors.forename: H
authors.initials: H
authors.lastname: Paulsen
authors.forename: G W
authors.initials: GW
authors.lastname: Schmidt
authors.forename: R E
authors.initials: RE
authors.lastname: Blankenship
mesh_terms: D061146:Chlorophyll Binding Proteins; D019281:Dimerization; D004735:Energy Transfer; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D045331:Photosystem I Protein Complex; D010860:Pigments, Biological / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants; D013054:Spectrophotometry, Atomic
chemical_list: D061146:Chlorophyll Binding Proteins; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D010860:Pigments, Biological; D010940:Plant Proteins