title: Electrogenicity at the secondary quinone acceptor site of cyanobacterial photosystem II.
abstract: Flash-induced generation of the electric potential difference (delta psi) by a direct electrometrical method was studied in Anacystis nidulans photosystem II-containing proteoliposomes associated with a phospholipid-impregnated collodion film. Besides a rapid phase of delta psi generation corresponding to charge separation between P680 and QA, an additional electrogenic phase with a characteristic time of 0.27 ms at pH 7.0 was observed after the second laser flash. The maximal amplitude of this phase was approx. 4% of that related to the P680+QA- formation. The sensitivity of this phase to DCMU, the flash-number dependence of its amplitude as well as the amplitude and the rate constant pH-dependences, indicate that it is due to the dismutation of QA- and QB- and to subsequent protonation of a doubly reduced plastoquinone QB2-.
authors.affiliation: Department of Cell Physiology and Immunology, School of Biology, Moscow State University, Russian Federation.
authors.forename: M D
authors.initials: MD
authors.lastname: Mamedov
authors.forename: O E
authors.initials: OE
authors.lastname: Beshta
authors.forename: V D
authors.initials: VD
authors.lastname: Samuilov
authors.lastname: Semenov AYu
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry*; D004563:Electrochemistry; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D011510:Proteolipids / Q000737:chemistry; D011809:Quinones / Q000737:chemistry*
chemical_list: D045322:Photosynthetic Reaction Center Complex Proteins; D011510:Proteolipids; D011809:Quinones; C020485:proteoliposomes