Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “CYTOCHROME OXIDASE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 577 records · Page 32Linked to original sources
PubMed2002

Up-regulation of cytochrome oxidase in the retina following optic nerve injury.

The purpose of this study is to investigate the cytochrome oxidase (COX) activity in the retina and optic nerve following an optic nerve injury. The optic nerve crush of one eye was carried out in Balb/c mice. A semi-quantitative RT-PCR method was then adopted to evaluate the mRNA expression of cytochrome oxidase subunit 1 (COX1) in the retina after surgery. Up-regulation of COX1 mRNA in the retina was detected by RT-PCR at 24 hr following the optic nerve injury. Total retinal mitochondrial mass measured by fluorescent intensity of MitoTracker green was not altered following the injury. COX histochemistry performed on cryostat sections showed an elevated enzyme activity of COX in the retina and in the optic nerve. In the retina, elevation of the COX activity was observed in the retinal ganglion cell layer and the overlying nerve fibre layer. The increase of COX activity began from 24 hr after injury, peaked around day 3, and maintained up to 1 week after the operation. In the optic nerve, increase of COX activity was observed in regions distal to the crush line and distributed either randomly or in a cone shape. In conclusion, both the expression of COX1 mRNA in retina and the activity of COX in inner plexiform layer and retinal ganglion cell layer were elevated following optic nerve injury without affecting total retinal mitochondrial mass. These findings suggested that one of early responses in the retina and in the optic nerve after the optic nerve injury is to scale up the energy production.

Animals↗
PubMed1988

Changes in concentrations of respiratory components and cytochrome oxidase activity in mitochondria obtained from carbon tetrachloride-induced cirrhotic rat liver.

1. Changes in the concentrations of respiratory components, phosphorylative activity, the cytochrome oxidase activity of mitochondria and the hepatic adenylate energy charge level (in situ) were studied in cirrhotic rat liver induced by carbon tetrachloride (CCl4). 2. In the cirrhotic liver mitochondria, concentrations of cytochrome a(+a3), cytochrome b, coenzyme Q9 and coenzyme Q10 increased significantly to 2.44 +/- 0.02 x 10(-10) (mean +/- SE), 1.37 +/- 0.05 x 10(-10), 25.57 +/- 0.47 x 10(-10) and 5.39 +/- 0.26 x 10(-10) mol/mg of mitochondrial protein, respectively, compared with 1.83 +/- 0.03 x 10(-10), 1.22 +/- 0.02 x 10(-10), 16.24 +/- 0.39 x 10(-10) and 1.81 +/- 0.07 x 10(-10) in normal rats [P less than 0.001 for cytochrome a(+a3), coenzyme Q9 and coenzyme Q10, and P less than 0.01 for cytochrome b]. 3. Concentrations of flavoprotein and pyridine nucleotides decreased significantly to 13.33 +/- 0.14 x 10(-10) and 45.68 +/- 1.59 x 10(-10) mol/mg of mitochondrial protein, respectively, compared with 14.79 +/- 0.33 x 10(-10) and 86.26 +/- 1.83 x 10(-10) in normal rats (P less than 0.001). There was no significant difference in the concentration of cytochrome c(+c1). 4. Cytochrome oxidase activity per unit of cytochrome a(+a3) increased significantly to 67.43 +/- 1.71 atoms O s-1 mol-1, compared with 55.77 +/- 1.16 in normal rats (P less than 0.001). By contrast, phosphorylative activity per unit of cytochrome a(+a3) decreased significantly in the cirrhotic liver to 10.40 +/- 0.36 s-1 compared with 13.43 +/- 0.49 in normal rats (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1993

Developmental changes in cytochrome oxidase histochemistry in the main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis spp.).

Developmental studies examining the changes in oxidative metabolic activity are useful for understanding how and if the vomeronasal and olfactory systems respond to stimulation during embryogenesis. Garter snakes are good candidates for examining the potential functionality of the vomeronasal system in utero. In adult garter snakes, the vomeronasal system mediates many behaviors. Neonatal garter snakes exhibit these same behaviors, and the vomeronasal system has been shown to mediate feeding behavior in neonates. Using cytochrome oxidase histochemistry, we examined changes in the oxidative metabolic activity of main and accessory olfactory bulbs of embryonic and neonatal garter snakes (Thamnophis sirtalis sirtalis and T. s. parietalis). Cytochrome oxidase staining is greater in the accessory olfactory bulb than in the main olfactory bulb of embryonic garter snakes. However, neonates show no differences in the staining of the accessory and main olfactory bulbs, suggesting a change in the stimulation of the main olfactory bulb after birth. This is the first report of cytochrome oxidase histochemistry in reptiles and in the vomeronasal system of embryonic vertebrates.

Aging↗
PubMed1981

A re-evaluation of the low-temperature kinetics of the reaction of fully reduced mitochondrial cytochrome oxidase with carbon monoxide and the spectral characterization of species Ic in the Soret and visible regions.

The kinetics of the reaction of fully reduced membrane bound cytochrome oxidase with CO following photolysis of the fully reduced cytochrome oxidase-CO complex habe been re-examined by re-analysing the data of Clore and Chance (1978) Biochem. J. 175, 709-725) at six temperatures in the 178-203 K range simultaneously at only a single wavelength pair, 444-463 nm. The choice of the 444-463 nm wavelength pair was based on the fact that the absorbance change produced at 444-463 nm on photolysis of the CO complex is sufficiently large and the separation between monitoring and reference wavelengths sufficiently small to render the effects of any possible time dependent scattering changes insignificant. On the basis of our analysis only a two step mechanism (Model 1 of Clore and Chance (1978) Biochem. J. 175, 709-725) satisfies the triple requirement of a S.D. within the standard error of the data, a random distribution of residuals and good determination of the optimized parameters. The single step mechanism of De Fonseka and Chance (1978) Biochem. J. 175, 1137-1138) fails to satisfy all three requirements. The pure difference spectra of species Ic minus E, E minus IIc and Ic minus IIc are calculated from the computed kinetics of the individual species and repetitive slow wavelength scanning difference spectra (reaction sample minus the CO complex) taken during the course of the reaction of fully reduced cytochrome oxidase with CO at 176 K.

Animals↗
PubMed2000

Angular dependences of perpendicular and parallel mode electron paramagnetic resonance of oxidized beef heart cytochrome c oxidase.

Cytochrome c oxidase catalyzes the reduction of oxygen to water with a concomitant conservation of energy in the form of a transmembrane proton gradient. The enzyme has a catalytic site consisting of a binuclear center of a copper ion and a heme group. The spectroscopic parameters of this center are unusual. The origin of broad electron paramagnetic resonance (EPR) signals in the oxidized state at rather low resonant field, the so-called g' = 12 signal, has been a matter of debate for over 30 years. We have studied the angular dependence of this resonance in both parallel and perpendicular mode X-band EPR in oriented multilayers containing cytochrome c oxidase to resolve the assignment. The "slow" form and compounds formed by the addition of formate and fluoride to the oxidized enzyme display these resonances, which result from transitions between states of an integer-spin multiplet arising from magnetic exchange coupling between the five unpaired electrons of high spin Fe(III) heme a(3) and the single unpaired electron of Cu(B). The first successful simulation of similar signals observed in both perpendicular and parallel mode X-band EPR spectra in frozen aqueous solution of the fluoride compound of the closely related enzyme, quinol oxidase or cytochrome bo(3), has been reported recently (Oganesyan et al., 1998, J. Am. Chem. Soc. 120:4232-4233). This suggested that the exchange interaction between the two metal ions of the binuclear center is very weak (|J| approximately 1 cm(-1)), with the axial zero-field splitting (D approximately 5 cm(-1)) of the high-spin heme dominating the form of the ground state. We show that this model accounts well for the angular dependences of the X-band EPR spectra in both perpendicular and parallel modes of oriented multilayers of cytochrome c oxidase derivatives and that the experimental results are inconsistent with earlier schemes that use exchange coupling parameters of several hundred wavenumbers.

Animals↗
PubMed1981

The effect of cytochrome oxidase on lipid chain dynamics. A nanosecond fluorescence depolarization study.

Molecular motions in membranes composed of purified cytochrome oxidase (EC 1.9.3.1) and synthetic lipid (L-alpha-dimyristoylphosphatidylcholine or L-alpha-dioleoylphosphatidylcholine) at various ratios were investigated with a lipophilic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Nanosecond fluorescence depolarization kinetics of the probe showed that the rod-shaped probe molecules perform a fast wobbling motion (restricted rotation) in all membranes studied, presumably reflecting the motion of lipid acyl chains. At temperatures where the pure lipid was in the liquid-crystalline phase, presence of cytochrome oxidase reduced the angular range of the wobbling motion, whereas its rate, the wobbling diffusion constant, was unaffected. On the other hand, incorporation of the protein into lipid in the gel phase resulted in the increase in the wobbling diffusion constant while the range of the wobbling motion remained the same. A time-dependent view of lipid dynamics that accounts for the above findings, as well as the results of recent electron spin resonance and nuclear spin resonance studies of protein-lipid interactions, is proposed.

Animals↗
PubMed1997

[Cytochrome oxidase distribution in the normal cat midbrain and after unilateral enucleation (a histochemical study)].

Histochemical method of cytochrome oxidase demonstration was used to study its distribution in frontal sections of tectum of the midbrain in cat in normal conditions and after unilateral enucleation. Basic layers of this formation were demonstrated in normal conditions similar to those revealed using classical histological methods. After unilateral enucleation rostral, middle and caudal parts of superior colliculus were stained differently. Contra- and ipsilateral surface layers in rostral and caudal parts were stained also with different intensity. Alteration of lightly and intensely stained patches appeared in middle part. Peculiarities of staining in cytochemical cytochrome oxidase demonstration in superior colliculus of tectum of the midbrain in enucleated animals are likely to reflect peculiarities of this structure afferentially by retinotectal, geniculotectal and geniculocortical fibres.

Animals↗
PubMedDate not supplied

Cytochrome oxidase: structural insights from electron microscopy and from secondary structure prediction.

Electron microscopic images of selectively contrasted cytochrome oxidase dimer crystals are interpreted in a manner consistent with the structure of monomers determined by Fuller et al. (J. Molec. Biol. 134, 305-327). The arms of the y-shaped monomers lie within and perpendicular to the lipid bilayer protruding approximately 25 A on the matrix side of the membrane. The cytoplasmic-side tails of two monomers spread apart in a dimer forming a large cleft. Decoration of the exposed matrix side of vesicle crystals with antisubunit IV antibody fragments indicates that subunit IV lies along the a-crystal axis roughly 20 A from the center of the dimer. A membrane propensity algorithm applied to the sequences of cytochrome oxidase subunits predicts a total of 19 transmembrane alpha-helices per monomer.

Binding Sites, Antibody↗
PubMed1978

Resonance Raman spectra of cytochrome oxidase. Evidence for photoreduction by laser photons in resonance with the Soret band.

Resonance Raman spectra of cytochrome oxidase solubilized in Tween 20 and sodium cholate, and excited at 413.1 nm have been recorded. Differences in the resonance Raman spectra of the two preparations are minimal indicating that the local environment of the hemes is similar in the two preparations. As in the work of Salmeen, et al. (1973) (Biochem. Biophys. Res. Commun. 52, 1100) the strongest band appears at 1358 cm-1. Some of the other bands differ slightly in their band shapes and frequencies when compared to their spectra; these differences can be accounted for by differences in resonance enhancement of the various bands wnen exciting at 441.6 and 413.1 nm. A study of the region from 1350 to 1380 cm-1 as a function of laser intensity (10--130 mW on sample) indicate that the doublet reported by Salmeen, et al. at 1358 and 1372 cm-1 is a result of photoreduction of the preparations. In samples to which potassium ferricyanide had been added, broad luminescence bands appear at 476 and 641 nm from which it is inferred that catalytic amounts of flavin in the preparations are photoreduced providing reducing equivalents to cytochrome oxidase.

Electron Transport Complex IV↗
PubMed1991

Effects of fatty acids on expression of genes encoding subunits of cytochrome c oxidase and cytochrome c oxidase activity in HT29 human colonic adenocarcinoma cells.

As the primary and preferred energy source of normal colonic epithelial cells, fatty acids may play a unique role in the differentiation and physiology of these cells. We have shown that expression levels of COXIII, a mitochondrial gene encoding one of the 13 subunits of cytochrome c oxidase, are abnormally low in colon tumors and colonic tissue at genetic risk for developing tumors but increase following in vitro treatment of HT29 human colonic adenocarcinoma cells with the fatty acid butyrate. The present studies investigate the specificity of fatty acids in effecting cytochrome c oxidase subunit expression and enzymatic activity in HT29 cells. The data demonstrate that, depending upon their chain length, metabolizable unbranched fatty acids increase expression of two subunits encoded by mitochondrial genes (I and III) and enhance cytochrome c oxidase activity. However, none of the fatty acids had an effect on expression of two subunits encoded by nuclear genes (IV and Va). These findings suggest that the low levels of COXIII expression exhibited in colonic tumors may represent a limiting factor in the assembly of functional cytochrome c oxidase and contribute to the depressed enzyme activity reported in these tumors. By elevating expression of subunits I and III and enzymatic activity, fatty acids may enhance the potential for cellular respiration. The more differentiated phenotype which is reported in colorectal carcinoma cell lines treated with fatty acids in vitro may be, therefore, associated with correction of metabolic abnormalities in transformed cells.

Adenocarcinoma↗
PubMed1989

Raman/absorption simultaneous measurements for cytochrome oxidase compound A at room temperature with a novel flow apparatus.

A novel flow apparatus for continuously producing reaction intermediates of cytochrome oxidase was constructed and applied successfully to observe the transient absorption and resonance Raman spectra in its reaction with oxygen. Time-resolved difference absorption spectra in 500-650-nm region clearly indicated the formation of compound A upon photolysis of the fully reduced CO-bound form at 5 degrees C, and at this stage electrons were not transferred from cytochrome c to cytochrome oxidase. However, at the stage of formation of compound B, cytochrome c was oxidized. Resonance Raman spectra of these intermediates measured simultaneously with the absorption spectra are also reported.

Absorption↗
PubMed1997

Cloning and characterization of KlCOX18, a gene required for activity of cytochrome oxidase in Kluyveromyces lactis.

We describe the isolation and initial characterization of KlCOX18, a gene that is essential for the assembly of a functional cytochrome oxidase in the yeast Kluyveromyces lactis. Cells carrying a recessive nuclear mutation in this gene are respiratory deficient and contain reduced levels of cytochromes a and a3. The KlCOX18 gene has been cloned by complementation of the respective nuclear mutation, sequenced, and disrupted. KlCOX18 is located on chromosome II and contains an open reading frame of 939 base pairs. The corresponding protein exhibits 70.4% similarity to the Cox18p of Saccharomyces cerevisiae. It contains three possible membrane-spanning domains and a putative amino-terminal mitochondrial import sequence. The strain carrying a null mutation in KlCOX18 does not grow on non-fermentable carbon sources and is deficient in both cytochrome c oxidase and respiratory activity. It is proposed that KlCox18p, like its S. cerevisiae counterpart, provides an important function at a later step of the cytochrome oxidase assembly pathway.

Amino Acid Sequence↗
PubMedDate not supplied

Stopped-flow studies of cytochrome oxidase reconstituted into liposomes: proton pumping and control of activity.

The transient kinetics of proton pumping and the electron transfer properties of cytochrome oxidase inserted into small unilamellar vesicles have been investigated by stopped-flow spectrophotometry. In the presence of valinomycin, proton pumping and cytochrome c oxidation by cytochrome oxidase are synchronous up to rate constants of approximately 9 sec-1. Moreover, the enzyme depleted of subunit III ("three-less oxidase") was also shown to pump protons, although with a significantly smaller stoichiometry. Thus, subunit III is not the only (or even the main) proton channel, although it may be involved in the regulation of activity. The kinetics of cytochrome c oxidation by COV in the absence and in the presence of ionophores have been investigated. Analysis of the time course of the process in the transient and steady state phases indicates that the onset of control by the electrochemical gradient follows the transfer of four electrons, i.e., one complete turnover of the oxidase. Two possible alternative interpretations for the control of the turnover phase are presented and discussed.

Animals↗
PubMedDate not supplied

Cytochrome oxidase inhibition: a novel animal model of Alzheimer's disease.

A profound decrease in activity of the mitochondrial enzyme cytochrome oxidase in blood platelets is a recently identified concomitant of Alzheimer's disease (AD). We investigated a possible pathogenic link between this finding and the symptoms of AD by mimicking this mitochondrial enzyme deficiency in rats. Rats were infused chronically with a selective inhibitor of cytochrome oxidase, sodium azide, or with saline delivered via subcutaneously implanted osmotic minipumps. The azide treatment impaired both spatial and nonspatial learning. Further, the azide treatment inhibited a low-threshold form of hippocampal long-term potentiation, primed burst potentiation. The behavioral deficits were not secondary to a sensory or motor impairment. Thus, chronic azide treatment of rats models some characteristics of AD.

Alzheimer Disease↗
PubMed1999

Stimulation of cellular XTT reduction by cytochrome oxidase inhibitors.

XTT reducing activity by CHO and L1210 cells was found to be stimulated by the presence of cytochrome oxidase inhibitors such as NaN3 or KCN. Among the other respiratory chain inhibitors, antimycin A (a complex III inhibitor) and chlorpromazine inhibited cellular XTT reduction, and rotenone and malonate showed slight inhibition and no effect, respectively. It is suggested that XTT reduction is coupled with the respiratory chain via cytochrome c, which is located between complexes III and IV (cytochrome oxidase).

Animals↗
PubMed1991

Genomic organization and sequence analysis of the cytochrome oxidase subunit II gene from normal and male-sterile mitochondria in sugar beet.

We have cloned and sequenced the cytochrome oxidase subunit II (coxII) gene from both normal and cytoplasmic male-sterile (CMS) sugar beet. The normal coxII (designated NcoxII) locus was found to be located 1491 bp upstream from the gene for cytochrome oxidase subunit I (coxI) on the same DNA strand and to have a 1463 bp intron which split the coding sequence into two exons (382 and 398 bp). The COXII protein contains 260 amino acid residues. We have also found two copies of the coxII gene (ScoxII-1 and ScoxII-2) to be present in the CMS genome. Our results suggest that the NcoxII gene diverges completely from the ScoxII-1 and ScoxII-2 genes 50 bp 5' to the ATG start codon. In addition, the ScoxII-1 and ScoxII-2 sequences could be readily discriminated from each other by the 3' end and the immediately adjacent flanking sequences of the gene: the 3' divergence results in a 101 codon extension of the ScoxII-2 ORF. Northern blot analysis demonstrates that the coxII gene exhibits altered transcript patterns in CMS compared with normal sugar beet. Different genomic arrangements of the coxII gene are considered to be the result of extensive intra- and inter-molecular recombination events involving the repeated DNA elements in the mitochondrial genome.

Amino Acid Sequence↗
PubMed1982

The maxicircle of Trypanosoma brucei kinetoplast DNA hybridizes with a mitochondrial gene encoding cytochrome oxidase subunit II.

A restriction endonuclease fragment of the maxicircle of Trypanosoma brucei brucei kinetoplast DNA hybridizes with a cloned mitochondrial DNA sequence which encodes cytochrome oxidase subunit II of Zea mays. A cloned mitochondrial DNA sequence encoding cytochrome oxidase subunit II of Saccharomyces cerevisiae also hybridized with kDNA, but exhibits less homology with the maxicircle than does the maize gene. The hybridizing maxicircle DNA was localized to a 2.8 kbp segment which is bounded by TaqI restriction endonuclease sites and nearby HindIII and EcoRI restriction sites. The TaqI restriction fragment is conserved between T. brucei brucei, T. brucei rhodesiense and T. brucei gambiense and hybridizes with the Zea mays probe in each case.

Animals↗
PubMed1987

Extended X-ray absorption fine structure of copper in CuA-depleted, p-(hydroxymercuri)benzoate-modified, and native cytochrome c oxidase.

Cytochrome c oxidase contains four redox-active metal centers: two heme irons, cytochromes a and a3, and two copper ions, CuA and CuB. Due to the paucity of spectroscopic signatures for both copper sites in cytochrome c oxidase, the ligands and structures for these sites have remained ambiguous. The specific depletion of CuA from the p-(hydroxymercuri)benzoate- (pHMB-) modified cytochrome c oxidase recently reported [Gelles, J., & Chan, S. I. (1985) Biochemistry 24, 3963-3972] is herein described. Characterization of this enzyme shows that the structures of the remaining metal centers are essentially unperturbed by the CuA modification and depletion (P. M. Li, J. Gelles, and S. I. Chan, unpublished results). Copper extended X-ray absorption fine structure (EXAFS) measurements on the CuA-depleted cytochrome c oxidase reveal coordination of three (N, O) ligands and one (S, Cl) ligand at the CuB site. Comparison of EXAFS results obtained for the CuA-depleted, pHMB-modified, and "unmodified control" enzymes has allowed the deconvolution of the EXAFS in terms of the inner coordination spheres for CuA as well as CuB. On the basis of these data, it is found that the structure for the CuA site is consistent with two (N, O) ligands and two S ligands.

Copper↗