title: Binuclear manganese (III) complexes as electron donors in D1/D2/cytochrome b559 preparations isolated from spinach photosystem II membrane fragments.
abstract: The capability of different manganese complexes to act as PS II electron donors in D1/D2/cytochrome b559 complexes has been analyzed by measuring actinic light-induced absorption changes at 680 nm (650 nm) and 340 nm, reflecting the photoaccumulation of Pheophytin⁻ (Pheo⁻) and the reduction of NADP⁺, respectively. The data obtained revealed: a) the donor capacity of synthetic binuclear Mn (III)₂complexes containing aromatic ligands significantly exceeds that for MnCl₂ in both cases, i.e. Pheo⁻ photoaccumulation and NADP⁺ reduction; b) manganese complexes can serve as suitable electron donors for light-induced NADP⁺ reduction catalyzed by D1/D2/cytochrome b559 complexes and ferredoxin plus ferredoxin-NADP⁺ reductase under anaerobic conditions and c) the specific turnover rate of the system leading to NADP⁺ reduction is extremely small. The implications of these findings are briefly discussed.
authors.affiliation: Institute of Soil Science and Photosynthesis, RAS, Puschino, Moscow Region 142292 Russia; Department of Chemistry, University of Gazi, Ankara, 06500, Turkey; Department of Chemistry, University of Poona, 411007, India.
authors.forename: S I
authors.initials: SI
authors.lastname: Allakhverdiev
authors.forename: M S
authors.initials: MS
authors.lastname: Karacan
authors.forename: G
authors.initials: G
authors.lastname: Somer
authors.forename: N
authors.initials: N
authors.lastname: Karacan
authors.forename: E M
authors.initials: EM
authors.lastname: Khan
authors.forename: S Y
authors.initials: SY
authors.lastname: Rane
authors.forename: S
authors.initials: S
authors.lastname: Padhye
authors.forename: V V
authors.initials: VV
authors.lastname: Klimov
authors.forename: G
authors.initials: G
authors.lastname: Renger