2y69 | pdb_00002y69

Bovine heart cytochrome c oxidase re-refined with molecular oxygen

spinqualitylabelsall models 2y69, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2y69 is a 20 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.95Å Ligands: CHD, CU, CUA, DMU, HEA, MG, OXY, PEK, PGV, TPO, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function COX1_BOVIN Cytochrome c oxidase is the component of the respiratory chain that catalyzes the reduction of oxygen to water. Subunits 1-3 form the functional core of the enzyme complex. CO I is the catalytic subunit of the enzyme. Electrons originating in cytochrome c are transferred via the copper A center of subunit 2 and heme A of subunit 1 to the bimetallic center formed by heme A3 and copper B. Publication Abstract from PubMed Cytochrome c oxidase (CcO) is the terminal enzyme of the respiratory chain. By reducing oxygen to water, it generates a proton gradient across the mitochondrial or bacterial membrane. Recently, two independent X-ray crystallographic studies ((Aoyama et al. Proc. Natl. Acad. Sci. USA 106 (2009) 2165-2169) and (Koepke et al. Biochim. Biophys. Acta 1787 (2009) 635-645)), suggested that a peroxide dianion might be bound to the active site of oxidized CcO. We have investigated this hypothesis by combining quantum chemical calculations with a re-refinement of the X-ray crystallographic data and optical spectroscopic measurements. Our data suggest that dianionic peroxide, superoxide, and dioxygen all form a similar superoxide species when inserted into a fully oxidized ferric/cupric binuclear site (BNC). We argue that stable peroxides are unlikely to be confined within the oxidized BNC since that would be expected to lead to bond splitting and formation of the catalytic P intermediate. Somewhat surprisingly, we find that binding of dioxygen to the oxidized binuclear site is weakly exergonic, and hence, the observed structure might have resulted from dioxygen itself or from superoxide generated from O(2) by the X-ray beam. We show that the presence of O(2) is consistent with the X-ray data. We also discuss how other structures, such as a mixture of the aqueous species (H(2)O+OH(-) and H(2)O) and chloride fit the experimental data. A combined quantum chemical and crystallographic study on the oxidized binuclear center of cytochrome c oxidase.,Kaila VR, Oksanen E, Goldman A, Bloch DA, Verkhovsky MI, Sundholm D, Wikstrom M Biochim Biophys Acta. 2011 Jan 4. PMID:21211513 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome c oxidase 3D structures

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