Publication Date:
1995-08-25
Description:
The high resolution three-dimensional x-ray structure of the metal sites of bovine heart cytochrome c oxidase is reported. Cytochrome c oxidase is the largest membrane protein yet crystallized and analyzed at atomic resolution. Electron density distribution of the oxidized bovine cytochrome c oxidase at 2.8 A resolution indicates a dinuclear copper center with an unexpected structure similar to a [2Fe-2S]-type iron-sulfur center. Previously predicted zinc and magnesium sites have been located, the former bound by a nuclear encoded subunit on the matrix side of the membrane, and the latter situated between heme a3 and CuA, at the interface of subunits I and II. The O2 binding site contains heme a3 iron and copper atoms (CuB) with an interatomic distance of 4.5 A; there is no detectable bridging ligand between iron and copper atoms in spite of a strong antiferromagnetic coupling between them. A hydrogen bond is present between a hydroxyl group of the hydroxyfarnesylethyl side chain of heme a3 and an OH of a tyrosine. The tyrosine phenol plane is immediately adjacent and perpendicular to an imidazole group bonded to CuB, suggesting a possible role in intramolecular electron transfer or conformational control, the latter of which could induce the redox-coupled proton pumping. A phenyl group located halfway between a pyrrole plane of the heme a3 and an imidazole plane liganded to the other heme (heme a) could also influence electron transfer or conformational control.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tsukihara, T -- Aoyama, H -- Yamashita, E -- Tomizaki, T -- Yamaguchi, H -- Shinzawa-Itoh, K -- Nakashima, R -- Yaono, R -- Yoshikawa, S -- New York, N.Y. -- Science. 1995 Aug 25;269(5227):1069-74.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute for Protein Research, Osaka University, Suita, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7652554" target="_blank"〉PubMed〈/a〉
Keywords:
Animals
;
Binding Sites
;
Cattle
;
Copper/*analysis
;
Crystallization
;
Crystallography, X-Ray
;
Electron Transport
;
Electron Transport Complex IV/*chemistry/metabolism
;
Fourier Analysis
;
Heme/*analogs & derivatives/analysis
;
Hydrogen Bonding
;
Magnesium/*analysis
;
Mitochondria, Heart/enzymology
;
Models, Molecular
;
Oxidation-Reduction
;
Oxygen/metabolism
;
Protein Conformation
;
Protein Structure, Secondary
;
Proton Pumps
;
Zinc/*analysis
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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