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          Institute: MPI für Biophysik     Collection: Abt. Molekulare Membranbiologie     Display Documents

ID: 472766.1, MPI für Biophysik / Abt. Molekulare Membranbiologie
High resolution crystal structure of Paracoccus denitrificans cytochrome c oxidase: New insights into the active site and the proton transfer pathways
Authors:Koepke, Juergen; Olkhova, Elena; Angerer, Heike; Müller, Hannelore; Peng, Guohong; Michel, Hartmut
Date of Publication (YYYY-MM-DD):2009-06
Title of Journal:Biochimica et Biophysica Acta (BBA) - Bioenergetics
Journal Abbrev.:Biochim. Biophys. Acta
Issue / Number:6
Start Page:635
End Page:645
Title of Issue:Structures and Mechanisms in Molecular Bioenergetics
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:The structure of the two-subunit cytochrome c oxidase from Paracoccus denitrificans has been refined using X-ray cryodata to 2.25 Å resolution in order to gain further insights into its mechanism of action. The refined structural model shows a number of new features including many additional solvent and detergent molecules. The electron density bridging the heme a3 iron and CuB of the active site is fitted best by a peroxogroup or a chloride ion. Two waters or OH groups do not fit, one water (or OH) does not provide sufficient electron density. The analysis of crystals of cytochrome c oxidase isolated in the presence of bromide instead of chloride appears to exclude chloride as the bridging ligand. In the D-pathway a hydrogen bonded chain of six water molecules connects Asn131 and Glu278, but the access for protons to this water chain is blocked by Asn113, Asn131 and Asn199. The K-pathway contains two firmly bound water molecules, an additional water chain seems to form its entrance. Above the hemes a cluster of 13 water molecules is observed which potentially form multiple exit pathways for pumped protons. The hydrogen bond pattern excludes that the CuB ligand His326 is present in the imidazolate form
Free Keywords:Electron transfer; Proton transfer; Proton pumping; X-ray crystallography; Membrane protein structure
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Biophysik/Abteilung Molekulare Membranbiologie
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