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PubMed1989

Evidence for cytochrome oxidase subunit I and a cytochrome c--subunit II fused protein in the cytochrome 'c1aa3' of Thermus thermophilus. How old is cytochrome oxidase?

The terminal cytochrome c1aa3 of the respiratory chain of Thermus thermophilus has been isolated and purified to homogeneity by a novel procedure. The two subunit proteins (55 and 33 kDa) have been characterized chemically. Computer searches with partial amino acid sequences obtained from both subunits show that the larger subunit belongs to the cytochrome oxidase subunit I protein family while the smaller covalently heme-binding subunit is not a cytochrome c1 but appears to be a fused protein between cytochrome c and cytochrome oxidase subunit II. With respect to the 16-S rRNA-derived phylogeny of procaryotes, the results show that the genetic information for an O2-reacting cytochrome oxidase (EC 1.9.3.1) existed already in early eubacteria.

Amino Acid Sequence↗
PubMed1979

Semiconduction as the mechanism of the cytochrome oxidase reaction. Low activation energy of semiconduction measured for cytochrome oxidase protein. Solid state theory of cytochrome oxidase predicts observed kinetic peculiarities.

Cytochrome oxidase protein has a measured activation energy of semiconduction much smaller than that of other proteins, falling within the range of the activation energy of the cytochrome oxidase reaction in solution. Many kinetic peculiarities of the cytochrome oxidase reaction difficult to explain by mass-action theories are easily accounted for if semiconduction is assumed to be the controlling mechanism.

Catalysis↗
PubMed1984

A comparison of the reactions of cytochrome c oxidase, cytochrome c and azurin with Cr2+ ions.

The reduction of cytochrome c oxidase (EC 1.9.3.1) by Cr2+ ions has been studied by stopped-flow spectrophotometry and is compared with the Cr2+ reduction of cytochrome c and azurin. The effects of temperature, pH, and added anions (e.g., SCN-) have been investigated. The behavior of the electron acceptor site of cytochrome c oxidase stands in contrast to that of the other redox proteins with regard to the effects of added anions and we suggest that this reflects the more buried nature of this site in the complex enzyme.

Animals↗
PubMed1988

The stoichiometry of charge translocation by cytochrome oxidase and the cytochrome bc1 complex of mitochondria at high membrane potential.

The q+/2e stoichiometries (number of charges translocated per electron pair transferred) of cytochrome oxidase and the cytochrome bc1 complex in rat liver mitochondria were determined at a range of membrane potentials up to 180 mV. The method used was similar to the one used in the preceding paper by us in this journal to determine the q+/O stoichiometry of the mitochondrial electron transport chain from succinate to oxygen. The measured q+/2e stoichiometry of cytochrome oxidase was 3.5 positive charges per O atom reduced at low membrane potential (120 mV) and it decreased to about 1.5 at high membrane potential (180 mV). The measured q+/2e stoichiometry of the cytochrome bc1 complex was between 1 and 1.25 positive charges ejected per electron pair and did not change significantly as delta psi was varied from 85 mV to 157 mV. The sum of the q+/2e stoichiometries of cytochrome oxidase and the cytochrome bc1 complex determined separately was similar to their value determined together for electron transport from succinate to oxygen over the range of membrane potentials studied. The most probable interpretation of these results is that the stoichiometry of the cytochrome bc1 complex is invariant over a range of membrane potentials and that the q+/2e stoichiometry of cytochrome oxidase decreases from 4 at low membrane potential to 2 at high membrane potential.

Animals↗
PubMed1991

Time-resolved magnetic circular dichroism spectroscopy of photolyzed carbonmonoxy cytochrome c oxidase (cytochrome aa3).

Nanosecond time-resolved magnetic circular dichroism (TRMCD) and time-resolved natural circular dichroism (TRCD) measurements of photolysis products of the CO complex of eukaryotic cytochrome c oxidase (CcO-CO) are presented. TRMCD spectra obtained at 100 ns and 10 microseconds after photolysis are diagnostic of pentacoordinate cytochrome a3Fe2+, as would be expected for simple photodissociation. Other time-resolved spectroscopies (UV-visible and resonance Raman), however, show evidence for unusual Fea3(2+) coordination after CO photolysis (Woodruff, W. H., O. Einarsdóttir, R. B. Dyer, K. A. Bagley, G. Palmer, S. J. Atherton, R. A. Goldbeck, T. D. Dawes, and D. S. Kliger. 1991. Proc. Nat. Acad. Sci. U.S.A. 88:2588-2592). Furthermore, time-resolved IR experiments have shown that photodissociated CO binds to CuB+ prior to recombining with Fea3(2+) (Dyer, R. B., O. Einarsdóttir, P. M. Killough, J. J. López-Garriga, and W. H. Woodruff. 1989. J. Am. Chem. Soc. 111:7657-7659). A model of the CcO-CO photolysis cycle which is consistent with all of the spectroscopic results is presented. A novel feature of this model is the coordination of a ligand endogenous to the protein to the Fe axial site vacated by the photolyzed CO and the simultaneous breaking of the Fe-imidazole(histidine) bond.

Binding Sites↗
PubMed2004

Development of microarray-based diagnostics of voles and shrews for use in biodiversity monitoring studies, and evaluation of mitochondrial cytochrome oxidase I vs. cytochrome b as genetic markers.

Molecular methods are widely used for species identification of mammals. In particular, the mitochondrial cytochrome b gene sequence has proven helpful for this purpose. Microarray technology can now open up new perspectives for biodiversity monitoring. With microarrays, many thousands of genetically based characteristics can be tested on one microscopic glass slide called a 'chip'. A 'Mammalia-Chip', for example, could include redundant diagnostic markers to unambiguously identify all European mammal species. Of broader use, and therefore economically more relevant, could be a 'Biodiversity-Chip', containing diagnostic features to distinguish key species in the taxa of bacteria, lichen, molluscs, insects, fungi, mammals, etc. An important prerequisite for any mixed-phyla chip is a standardization of methods. One of the most promising genes as a universal marker for all eukaryotes is cytochrome oxidase I. We show that cytochrome oxidase I is adequate for the discrimination of different species of voles and shrews with cluster analysis. Based on these results we present a diagnostic microarray-chip using cytochrome oxidase I sequences for the identification of three species of Sorex (Soricidae, Insectivora) and four species of Microtus (Arvicolinae, Rodentia). We conclude that cytochrome oxidase I can be used as an alternative marker to cytochrome b in a mixed-phyla chip, or both genes can be used in combination to enhance redundance and thus robustness of a specific chip including small mammals.

Animals↗
PubMed2001

Properties of the detergent solubilised cytochrome c oxidase (cytochrome cbb(3)) purified from Pseudomonas stutzeri.

Cytochrome cbb(3) is a cytochrome c-oxidising isoenzyme that belongs to the superfamily of respiratory haem/copper oxidases. We have developed a purification method yielding large amounts of pure cbb(3) complex from the soil bacterium Pseudomonas stutzeri. This cytochrome cbb(3) complex consists of three subunits (ccoNOP) in a 1:1:1 stoichiometry and contains two b-type and three c-type haems. The protein complex behaves as a monomer with an overall molecular weight of 114.0+/-8.9 kDa and a s(0)(20,w) value of 8.9+/-0.3 S as determined by analytical ultracentrifugation. Crystals diffracting to 5.0 A resolution have been grown by the vapour diffusion sitting drop method to an average size of 0.1 x 0.1 x 0.3 mm. This is the first crystallisation report of a (cbb(3))-type oxidase.

Amino Acid Sequence↗
PubMed2002

Aeropyrum pernix K1, a strictly aerobic and hyperthermophilic archaeon, has two terminal oxidases, cytochrome ba3 and cytochrome aa3.

Aeropyrum pernix K1 is a strictly aerobic and hyperthermophilic archaeon that thrives even at 100 degrees C. The archaeon is quite interesting with respect to the evolution of aerobic electron transport systems and the thermal stability of the respiratory components. An isolated membrane fraction was found to oxidize bovine cytochrome c. The activity was solubilized in the presence of detergents and separated into two fractions by successive chromatography. Two cytochrome oxidases, designated as CO-1 and CO-2, were further purified. CO-1 was a ba(3)-type cytochrome containing at least two subunits. Chemically digested fragments of CO-1 revealed a peptide with a sequence identical to a part of a putative cytochrome oxidase subunit I encoded by the gene ape1623. CO-2, an aa(3)-type cytochrome, was present in lower amounts than CO-1 and was immunologically identified as a product of aoxABC gene (DDBJ accession no. AB020482). Both cytochromes reacted with carbon monoxide. The apparent K(m) values of CO-1 and CO-2 for oxygen were 5.5 and 32 micro M, respectively, at 25 degrees C. The terminal oxidases CO-1 and CO-2 phylogenetically correspond to the SoxB and SoxM branches, respectively, of the heme-copper oxidase tree.

Aerobiosis↗