title: The photosystem I trimer of cyanobacteria: molecular organization, excitation dynamics and physiological significance.
abstract: The photosystem I complex organized in cyanobacterial membranes preferentially in trimeric form participates in electron transport and is also involved in dissipation of excess energy thus protecting the complex against photodamage. A small number of longwave chlorophylls in the core antenna of photosystem I are not located in the close vicinity of P700, but at the periphery, and increase the absorption cross-section substantially. The picosecond fluorescence kinetics of trimers resolved the fastest energy transfer components reflecting the equilibration processes in the core antenna at different redox states of P700. Excitation kinetics in the photosystem I bulk antenna is nearly trap-limited, whereas excitation trapping from longwave chlorophyll pools is diffusion-limited and occurs via the bulk antenna. Charge separation in the photosystem I reaction center is the fastest of all known reaction centers.
authors.affiliation: A.N. Bakh Institute of Biochemistry, Russian Academy of Sciences, 117071, Moscow, Russia. inbio@glas.apc.org
authors.forename: N V
authors.initials: NV
authors.lastname: Karapetyan
authors.forename: A R
authors.initials: AR
authors.lastname: Holzwarth
authors.forename: M
authors.initials: M
authors.lastname: Rögner
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D045342:Light-Harvesting Protein Complexes; D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism*; D045331:Photosystem I Protein Complex; D013329:Structure-Activity Relationship
chemical_list: D045342:Light-Harvesting Protein Complexes; D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex