@prefix prodottidellaricerca: . @prefix istituto: . @prefix prodotto: . istituto:CDS063 prodottidellaricerca:prodotto prodotto:ID40013 . @prefix pubblicazioni: . @prefix unitaDiPersonaleInterno: . unitaDiPersonaleInterno:MATRICOLA671 pubblicazioni:autoreCNRDi prodotto:ID40013 . @prefix modulo: . modulo:ID2683 prodottidellaricerca:prodotto prodotto:ID40013 . @prefix rdf: . prodotto:ID40013 rdf:type prodotto:TIPO1101 . @prefix retescientifica: . prodotto:ID40013 rdf:type retescientifica:ProdottoDellaRicerca . @prefix rdfs: . prodotto:ID40013 rdfs:label "Water Activity Regulates the QA to QB Electron Transfer in Photosynthetic Reaction Centers from Rhodobacter sphaeroides (Articolo in rivista)"@en . @prefix xsd: . prodotto:ID40013 pubblicazioni:anno "2008-01-01T00:00:00+01:00"^^xsd:gYear ; pubblicazioni:doi "10.1021/ja801963a"^^xsd:string . @prefix skos: . prodotto:ID40013 skos:altLabel "
Palazzo G.; Francia F.; Mallardi A.; Giustini M.; Lopez F.; Venturoli G. (2008)
Water Activity Regulates the QA to QB Electron Transfer in Photosynthetic Reaction Centers from Rhodobacter sphaeroides
in Journal of the American Chemical Society (Print)
"^^rdf:HTML ; pubblicazioni:autori "Palazzo G.; Francia F.; Mallardi A.; Giustini M.; Lopez F.; Venturoli G."^^xsd:string ; pubblicazioni:paginaInizio "9353"^^xsd:string ; pubblicazioni:paginaFine "9363"^^xsd:string ; pubblicazioni:numeroVolume "130"^^xsd:string . @prefix ns11: . prodotto:ID40013 pubblicazioni:rivista ns11:ID372001 ; skos:note "ISI Web of Science (WOS)"^^xsd:string , "Scopus"^^xsd:string ; pubblicazioni:affiliazioni "Dipartimento di Chimica and CSGI, UniVersita` di Bari, Via Orabona 4, I-70126, Bari, Italy;\nDipartimento di Biologia and CNISM, UniVersita` di Bologna, Italy; \nIstituto per i Processi Chimico-Fisici, CNR, Via Orabona 4, 70126 Bari, Italy;\nCSGI and Dipartimento di Chimica, UniVersita` \\\"La Sapienza\\\", I-00185 Roma, Italy"^^xsd:string ; pubblicazioni:titolo "Water Activity Regulates the QA to QB Electron Transfer in Photosynthetic Reaction Centers from Rhodobacter sphaeroides"^^xsd:string ; prodottidellaricerca:abstract "We report on the effects of water activity and surrounding viscosity on electron transfer reactions\ntaking place within a membrane protein: the reaction center (RC) from the photosynthetic bacterium\nRhodobacter sphaeroides. We measured the kinetics of charge recombination between the primary\nphotoxidized donor (P+) and the reduced quinone acceptors. Water activity (aW) and viscosity (?) have\nbeen tuned by changing the concentration of cosolutes (trehalose, sucrose, glucose, and glycerol) and the\ntemperature. The temperature dependence of the rate of charge recombination between the reduced primary\nquinone, QA\n-, and P+ was found to be unaffected by the presence of cosolutes. At variance, the kinetics\nof charge recombination between the reduced secondary quinone (QB\n-) and P+ was found to be severely\ninfluenced by the presence of cosolutes and by the temperature. Results collected over a wide ?-range (2\norders of magnitude) demonstrate that the rate of P+QB\n- recombination is uncorrelated to the solution\nviscosity. The kinetics of P+QB\n- recombination depends on the P+QA\n-QB T P+QAQB\n- equilibrium constant.\nAccordingly, the dependence of the interquinone electron transfer equilibrium constant on T and aW has\nbeen explained by assuming that the transfer of one electron from QA\n- to QB is associated with the release\nof about three water molecules by the RC. This implies that the interquinone electron transfer involves at\nleast two RC substates differing in the stoichiometry of interacting water molecules.\nIntroduction\nProteins are characterized by a complex conformational\ndynamics. The wide range of internal motions they experience\nat physiological temperatures originates from rugged energy\nlandscapes, which feature an extremely large number of minima\ncorresponding to different conformational substates, organized\nin hierarchical tiers.1-3 This ability of the protein to perform\nstructural fluctuations among many different conformational\nsubstates appears to be intimately connected to protein function.4,5\nThe photosynthetic reaction center (RC) from purple bacteria\nis becoming a paradigmatic system in the study of the\nrelationship between electron transfer processes and protein\nconformational dynamics. This membrane chromoprotein, following\nphoton absorption by the primary electron donor P (a\nbacteriochlorophyll dimer), catalyzes a sequential"@en ; prodottidellaricerca:prodottoDi istituto:CDS063 , modulo:ID2683 ; pubblicazioni:autoreCNR unitaDiPersonaleInterno:MATRICOLA671 . ns11:ID372001 pubblicazioni:rivistaDi prodotto:ID40013 .