6juw | pdb_00006juw

BOVINE HEART CYTOCHROME C OXIDASE IN CATALITIC INTERMEDIATES AT 1.80 ANGSTROM RESOLUTION

spinqualitylabelsall models 6juw, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6juw 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 1.8Å Ligands: CDL, CHD, CU, CUA, DMU, EDO, FME, HEA, MG, NA, PEK, PGV, PO4, PSC, SAC, TGL, 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) reduces O2 to water, coupled with a proton-pumping process. The structure of the O2-reduction site of CcO contains two reducing equivalents, Fe a3 (2+) and CuB (1+), and suggests that a peroxide-bound state (Fe a3 (3+)-O(-)-O(-)-CuB (2+)) rather than an O2-bound state (Fe a3 (2+)-O2) is the initial catalytic intermediate. Unexpectedly, however, resonance Raman spectroscopy results have shown that the initial intermediate is Fe a3 (2+)-O(2), whereas Fe a3 (3+)-O(-)-O(-)-CuB (2+) is undetectable. Based on X-ray structures of static non-catalytic CcO forms and mutation analyses for bovine CcO, a proton-pumping mechanism has been proposed. It involves a proton-conducting pathway (the H-pathway) comprising a tandem hydrogen-bond network and a water channel located between the N and P side surfaces. However, a system for unidirectional proton-transport has not been experimentally identified. Here, an essentially identical X-ray structure for the two catalytic intermediates (P and F) of bovine CcO was determined at 1.8 A resolution. A 1.70 A Fe-O distance of the ferryl center could be best described as Fe a3 (4+)=O(2-), not as Fe a3 (4+)-OH(-) The distance suggests a ~800 cm(-1) Raman stretching band. We found an interstitial water molecule which could trigger a rapid proton-coupled electron transfer from tyrosine-OH to the slowly forming Fe a3 (3+)-O(-)-O(-)-CuB (2+) state, preventing its detection, consistent with the unexpected Raman results. The H-pathway structures of both intermediates indicated that during proton-pumping from the hydrogen-bond network to the P-side, a transmembrane helix closes the water channel connecting the N-side with the hydrogen-bond network, facilitating unidirectional proton-pumping during the P-to-F transition. X-ray structures of catalytic intermediates of cytochrome c oxidase provide insights into its O2-activation and unidirectional proton-pump mechanisms.,Shimada A, Etoh Y, Kitoh-Fujisawa R, Sasaki A, Shinzawa-Itoh K, Hiromoto T, Yamashita E, Muramoto K, Tsukihara T, Yoshikawa S J Biol Chem. 2020 Mar 12. pii: RA119.009596. doi: 10.1074/jbc.RA119.009596. PMID:32165497 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Cytochrome c oxidase 3D structures

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