title: Semiquinone oscillations as a tool for investigating the ubiquinone binding to photosynthetic reaction centers.
abstract: Semiquinone oscillations induced by light pulses in the presence of exogenous electron donors are a valuable source of information on the kinetics and thermodynamics of ubiquinone chemistry relevant to the QB site of the photosynthetic reaction center (RC). In previous attempts to achieve the quantitative interpretation of data, the ubiquinone concentration was considered constant during the experiment since it was much bigger than that of RC. In this work, we extended existing models to low ubiquinone concentrations revealing several hidden processes taking place during the ubiquinone photoreduction and enabling the evaluation of the ubiquinone binding constant K Q at the QB site. The proposed approach provides for the first time the evaluation of K Q without any preliminary treatment of ubiquinone extraction from the binding site, thereby better preserving its native structure.
authors: Department of Chemistry, University of Bari, 70126, Bari, Italy.
authors: Fulvio
authors: F
authors: Ciriaco
authors: Rocco Roberto
authors: RR
authors: Tangorra
authors: Alessandra
authors: A
authors: Antonucci
authors: Livia
authors: L
authors: Giotta
authors: Angela
authors: A
authors: Agostiano
authors: Massimo
authors: M
authors: Trotta
authors: Francesco
authors: F
authors: Milano
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012242:Rhodobacter sphaeroides / Q000201:enzymology; D013053:Spectrophotometry / Q000379:methods; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D014451:Ubiquinone; C024989:coenzyme Q10