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Hamburg, Germany

Kachalova G.S.,Max Planck Institute of Biochemistry | Shosheva A.C.,Bulgarian Academy of Science | Bourenkov G.P.,EMBL Outstation Hamburg | Donchev A.A.,Bulgarian Academy of Science | And 2 more authors.
Journal of Inorganic Biochemistry | Year: 2012

Plastocyanin (PC) from poplar leaves is present in two isoforms, PCa and PCb, which differ in sequence by amino acid replacements at locations remote from the copper center and simultaneously act in the photosynthetic electron-transport chain. We describe ultra-high resolution structures of PCa and high-resolution structures of PCb, both under oxidizing and reducing conditions at pH 4, 6 and 8. The docking on cytochrome f and photosystem I, respectively, has been modeled for both isoforms. PCa and PCb exhibit closely similar overall and active-site structures, except for a difference in the relative orientation of the acidic patches. The isoforms exhibit substantial differences in the dependence of the reduced (CuI) geometry on pH. In PCa, the decrease in pH causes a gradual dissociation of His87 from Cu I at low pH, probably adopting a neutral tautomeric state. In PCb, the histidine remains covalently bound to CuI and may adopt a doubly protonated state at low pH. The fact that both isoforms have similar although not identical functions in photosynthetic electron flows suggests that the His87 imidazole does not play a crucial role for the pathway of electron transport from cytochrome f to oxidized PC. © 2012 Elsevier Inc. All rights reserved.

Neuba A.,University of Paderborn | Florke U.,University of Paderborn | Meyer-Klaucke W.,EMBL Outstation Hamburg | Salomone-Stagni M.,EMBL Outstation Hamburg | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2011

A mixed-valent redox-active copper thiolate complex is formed in the reaction of [Cu(MeCN)4]PF6 with a CPh3 thioether by a combination of homo- and heterolytic cleavage of the S-CPh 3 bond. In its oxidized state, the hexanuclear copper sulfur cluster (see picture) has the same average metal oxidation state as the dinuclear copper thiolate center of cytochrome c oxidase or N2O reductase. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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