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Main Title: Elucidating mechanisms in haem copper oxidases: The high-affinity Q(H) binding site in quinol oxidase as studied by DONUT-HYSCORE spectroscopy and density functional theory
Author(s): MacMillan, Fraser
Kacprzak, Sylwia
Hellwig, Petra
Grimaldi, Stephane
Michel, Hartmut
Kaupp, Martin
Type: Article
Language Code: en
Abstract: The Cytochrome bo3 ubiquinol oxidase (QOX) from Escherichia coli (E. coli) contains a redox-active quinone, the so-called “high-affinity” QH quinone. The location of this cofactor and its binding site has yet to be accurately determined by X-ray crystallographic studies. Based on site-directed mutagenesis studies, a putative quinone binding site in the protein has been proposed. The exact binding partner of this cofactor and also whether it is stabilised as an anionic semiquinone or as a neutral radical species is a matter of some speculation. Both Hyperfine Sub-level Correlation (HYSCORE) and Double Nuclear Coherence Transfer Spectroscopy (DONUT-HYSCORE) spectroscopy as well as density functional theory (DFT) have been applied to investigate the QH binding site in detail to resolve these issues. Use is made of site-directed variants as well as globally 15N/14N-exchanged protein. Comparison of computed and experimental 13C hyperfine tensors provides strong support for the binding of the semiquinone radical in an anionic rather than a neutral protonated form. These results are compared with the corresponding information available on other protein binding sites and/or on model systems and are discussed with regard to the location and potential function of QH in the overall mechanism of function of this family of haem copper oxidases.
Issue Date: 2011
Date Available: 30-Jun-2016
DDC Class: 540 Chemie und zugeordnete Wissenschaften
Sponsor/Funder: DFG, SFB 472, Molekulare Bioenergetik
Journal Title: Faraday discussions
Publisher: Royal Society of Chemistry
Publisher Place: Cambridge
Volume: 148
Publisher DOI: 10.1039/c005149g
Page Start: 315
Page End: 344
EISSN: 1364-5498
ISSN: 1359-6640
Notes: Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
Appears in Collections:Inst. Chemie » Publications

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