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PubMed1988

Cytochrome oxidase histochemistry in the effect of light deprivation on the fly visual system.

Deprivation of visual experience for a short time during the early period postemergence in the fly influences strongly the development of visual pattern discrimination. Cytochrome oxidase histochemistry was used to examine the effect of visual deprivation on the development of the neuronal network in the optic lobe. Flies in which one compound eye was covered immediately after emergence were raised under normal light and dark conditions (LD). Other flies were raised without covering of the compound eyes under LD or continuous darkness (DD) as controls. At various periods of postemergence flies from the 3 groups were used for histochemistry. The results indicated that the deprivation caused by unilateral eye covering produced a decrease in cytochrome oxidase staining of the covered side of the retina and optic lobe, but not in the central part of the brain. This asymmetry in staining was not seen in flies of 1-5 days postemergence but became evident after the sixth day postemergence. When flies were raised in DD until the 5th day postemergence and then in LD, the development of asymmetry in cytochrome oxidase staining was delayed. These results confirm previous behavioral experiments on visual deprivation. Both suggest that visual deprivation during the early period of postemergence leads to a long-lasting decrease in neuronal activity.

Animals↗
PubMed1993

Interaction of carbonyl cyanide 3-chlorophenylhydrazone with cytochrome c oxidase.

Cytochrome c oxidase binds protonophore carbonyl cyanide 3-chlorophenylhydrazone (CCCP) with high affinity. There are 1.46 high-affinity binding sites per cytochrome c oxidase for CCCP with dissociation constant 2.7 x 10(-7) mol/l. The bond between the CCCP and cytochrome c oxidase accomplishes through the group on cytochrome c oxidase with pKa 6.64 and is based on the electrostatic interaction. Interaction of CCCP with low-affinity binding sites of cytochrome c oxidase induces the shift of the anion CCCP spectrum to UV-region. The similar effect is characteristic for CCCP interaction with protons. Lipophilic non-dissociated derivative NCH3CCP is not binding to cytochrome c oxidase.

Binding Sites↗
PubMed1981

Selective cytochemical localization of peroxidase, cytochrome oxidase and catalase in rat liver with 3,3'-diaminobenzidine.

In rat liver, three different enzymes with peroxidatic activity are demonstrated with modifications of the DAB-technique: peroxidase in the endoplasmic reticulum of Kupffer cells, catalase in peroxisomes and cytochrome oxidase in mitochondria. The major problem of the DAB-methods is their limited specificity so that often in tissues incubated for one enzyme the other two proteins are also stained simultaneously. We have studied the conditions for selective staining of each of these three enzymes in rat liver fixed either by perfusion with glutaraldehyde or by immersion in a modified Karnovsky's glutaraldehyde-formaldehyde fixative. The observations indicate that in perfusion fixed material selective staining can be obtained by reduction of the incubation time (5 min) and the use of optimal conditions for each enzyme. In livers fixed by immersion the distribution of the staining is patchy and irregular and usually longer incubation times (15-30 min) are required. Selective staining of peroxidase in Kupffer cells was obtained by brief incubation at room temperature in a medium containing 2.5 mM DAB in cacodylte buffer pH 6.5 and 0.02% H2O2. The exclusive staining for cytochrome oxidase in cristae of mitochondria was achieved after short incubation in 2.5 mM DAB in phosphate buffer pH 7.2 containing 0.05% cytochrome c. For selective demonstration of catalase in peroxisomes the tissue was incubated in 5 mM DAB in Teorell-Stenhagen (or glycine-NaOH) buffer at pH 10.5 and 0.15% H2O2. The prolongation of the incubation time in peroxidase medium caused marked staining of both mitochondria and peroxisomes. In the cytochrome oxidase medium longer incubations led to slight staining of peroxisomes. The catalase medium was quite selective for this enzyme so that even after incubation for 120 min only peroxisomes stained.

3,3'-Diaminobenzidine↗
PubMed1979

A re-evaluation of some basic structural and functional properties of Pseudomonas cytochrome oxidase.

Determinations of iron content and dry-weight measurements on samples of Pseudomonas cytochrome oxidase were coupled with sodium dodecyl sulphate/polyacrylamide-gel-electrophoresis studies of both the native protein and covalently cross-linked oligomers in order to estimate the enzyme's molecular weight and spectral absorption coefficients. A value of epsilon(ox.) (410)=282x10(3) litre.mol(-1).cm(-1) was calculated for a dimeric protein molecule having a total molecular weight of 122000 (based on iron analysis). Steady-state kinetic observations of the enzyme-catalysed oxidation of reduced azurin by nitrite indicated a marked increase in enzyme inactivation as the pH was raised from 5.7 to 7.2. Since NO, a product of the nitrite reductase activity of Pseudomonas cytochrome oxidase, is known to bind to the enzyme, a study was undertaken to try to assess the potential of NO as a product inhibitor. Investigations showed that samples of the oxidized protein at pH values 4, 5 and 6 bound NO to both haem c and d(1) components, but oxidized enzyme samples at pH7 and above formed their reduced ligand-bound forms when placed under an atmosphere of the gas. Ascorbate-reduced enzyme samples at pH4, 5, 6 and 7 were also found to bind NO at both haem components, although at pH7 the rate of haem c binding was very slow. At pH8 and 9 only the ferrohaem d(1) bound NO. Titration experiments on the reduced protein over the pH range 5-7, with nitrite as a precursor of NO, showed that the haem d(1) had a much higher affinity than the haem c: experiments at pH5.2 and 5.9 with NO-equilibrated solutions revealed the same pattern of behaviour with the oxidized enzyme.

Chemical Phenomena↗
PubMed2004

Important roles of tyrosines in photosystem II and cytochrome oxidase.

Theoretical studies (B3LYP) on models of the active sites in Photosystem II (PSII) and cytochrome oxidase are discussed. The role of a tyrosyl radical in the O-O bond formation in PSII is investigated, as well as the tyrosyl radical formation. In cytochrome oxidase, mechanisms for O-O bond cleavage involving tyrosyl radical formation are investigated, together with possible roles for the tyrosine in the proton translocation.

Electron Transport↗
PubMed1984

Three variant introns of the same general class in the mitochondrial gene for cytochrome oxidase subunit 1 in Aspergillus nidulans.

The oxiA gene of Aspergillus nidulans, coding for cytochrome oxidase subunit 1, is shown by DNA sequencing to contain three introns. An AUG start codon is not present at the beginning of the sequence, suggesting that either another codon, possibly the four base codon AUGA, is used for initiation or there is a further short intron between the true start codon and the beginning of the recognisable coding region. The second and third introns have long open reading frames, which could code for maturase proteins. The lack of conservation of amino acid sequence in the putative region of proteolytic cleavage for maturase formation suggests that the first conserved decapeptide may act as the recognition signal for protein processing. The third intron is remarkably (70%) homologous to the second intron of the cytochrome oxidase subunit 1 gene of Schizosaccharomyces pombe and both are located in exactly the same position. The third Aspergillus intron has an in-frame insertion of a 37-bp GC-rich DNA sequence which is now flanked by a 5-bp repeat, a well-known feature of transposable elements. All three introns in the oxiA gene have a 'core' RNA secondary structure found in a class of introns fitting the RNA splicing model of Davies et al. (1982). This core RNA structure may play a catalytic as well as a structural role in intron splicing. A sequence within the intron could act as a guide to align the splice sites of two of the introns in accordance with the model of Davies et al.

Aspergillus nidulans↗
PubMed1978

Enzyme behaviour and molecular environment. The effects of ionic strength, detergents, linear polyanions and phospholipids on the pH profile of soluble cytochrome oxidase.

The activity vs. pH profile for the oxidation of ferrocytochrome c by purified cytochrome oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1) was investigated as a function of ionic strength (from 10 to 200 mM) in the absence and in the presence of various perturbants: Tween 20, linear polyanions (RNA, heparin, polyglutamic acid) and phospholipids (asolectin, phosphatidylcholine, phosphatidic acid and cardiolipin). The activation induced by Tween 20 and "zero net charge" phospholipid liposomes was not pH dependent. On the other hand, linear polyanions and polyanionic liposomes strongly perturbed the pH profile, mostly at low ionic strength, by shifting the pH optimum about 1.7 pH units towards alkaline pH values. This effect was reversed by increasing ionic strength. These observations are interpreted in the light of polyelectrolyte theory. Since these results show striking with membrane-bound enzyme, it is concluded that in vivo cytochrome oxidase is located within polyanionic sites of the micochondrial membrane. The activation broght about by phospholipids may result from two posible processes: creation of a hydrophobic environment by the non-polar tails, preventing autoaggregation; and creation of a suitable polyelectrolytic environment by the polar heads (of non zero net charge), increasing the intrinsic reaction rate.

Animals↗
PubMed1996

Influence of altered gravity on the cytochemical localization of cytochrome oxidase activity in central and peripheral gravisensory systems in developing cichlid fish.

Cichlid fish larvae were reared from hatching to active free swimming under different gravity conditions: natural environment, increased acceleration in a centrifuge, simulated weightlessness in a clinostat and near weightlessness during space flight. Cytochrome oxidase activity was analyzed semiquantitatively on the ultrastructural level as a marker of regional neuronal activity in a primary, vestibular brainstem nucleus and in gravity receptive epithelia in the inner ear. Our results show, that gravity seems to be positively correlated with cytochrome oxidase activity in the magnocellular nucleus of developing fish brain. In the inner ear the energy metabolism is decreased under microgravity concerning utricle but not saccule. Hypergravity has no effect on cytochrome oxidase activity in sensory inner ear epithelia.

Animals↗
PubMed1990

Spectral and catalytic properties of cytochrome oxidase in organic solvents.

Isolated bovine heart cytochrome oxidase has been extracted into n-hexane, probably in reverse micelles, by the use of asolectin and calcium. The diluted extracts are composed of particles with the hydrodynamic radius of 42 nm. Spectral characteristics of the extracted oxidase are similar to those in aqueous solutions. At the high molar ratio of water to phospholipid (W0 = 8) in an organic solvent both cytochrome a and a3 are reducible and oxygen uptake is observed. However, at low W0 (W0 = 1.8) the rate of cytochrome a reduction is decreased and reduction of cytochrome a3 is inhibited.

Animals↗
PubMedDate not supplied

[Effect of histones on mouse liver mitochondria cytochrome oxidase activity in vitro and in vivo].

Histones at concentration of 2-10 micrograms/ml activated the mitochondrial cytochrome oxidase and at concentration of 25 micrograms/ml and higher--inhibited the enzyme in vitro. Cytochrome oxidase was completely inactivated by histones at concentration of 100 mg/microliter and higher. After administration in vivo histones modified the reaction of liver mitochondria in response to the subsequent treatment with a non-ion detergent Triton X-100. Possible pathogenetic importance of the phenomena observed is discussed.

Animals↗
PubMed1980

The localization of tightly bound cardiolipin in cytochrome oxidase.

One to two molecules of tightly bound cardiolipin are associated with resolved fractions of cytochrome oxidase containing subunits I to III or I to IV. Large scale isolation of subunits I to IV indicates the presence of approximately 0.5 molecule of cardiolipin per molecule of subunit I. Lipoprotein staining of sodium dodecyl sulfate/urea/acrylamide gels of cytochrome oxidase support the findings that subunit I is a lipoprotein. The resistance of this tightly bound cardiolipin to organic solvent extraction suggests a specific association of some tenacity with the protein.

Binding Sites↗
PubMed2005

Characteristics of cytochrome oxidase activity in visual system neurons in kittens reared in conditions of flashing illumination.

The studies reported here addressed the effects of flashing (15 Hz) lights on the metabolic activity of visual system neurons in animals reared in condition of crepuscular illumination. Activity of the respiratory enzyme cytochrome oxidase was detected in the cortex of visual areas 17 and 18 and in the lateral geniculate body in kittens. The results showed that kittens subjected to this stimulation, unlike intact kittens and kittens reared in conditions of crepuscular illumination, showed a change in the pattern of cytochrome oxidase distribution in cortical field 17 consisting of the appearance of alternating areas of increased and decreased enzyme activity in layers III and IV. In cortical field 18 and the lateral geniculate body, experimental kittens showed no changes in the cytochrome oxidase activity distribution pattern. It is suggested that flashing illumination leads to disturbance of the balance in activity in the Y and X conducting channels of the visual system.

Animals↗
PubMed2001

Light-emitting diode treatment reverses the effect of TTX on cytochrome oxidase in neurons.

Light close to and in the near-infrared range has documented benefits for promoting wound healing in human and animals. However, mechanisms of its action on cells are poorly understood. We hypothesized that light treatment with a light-emitting diode array at 670 nm (LED) is therapeutic in stimulating cellular events involving increases in cytochrome oxidase activity. LED was administered to cultured primary neurons whose voltage-dependent sodium channels were blocked by tetrodotoxin. The down-regulation of cytochrome oxidase activity by TTX was reverted to control levels by LED. LED alone also up-regulated enzyme activity. Thus, the results are consistent with our hypothesis that LED has a stimulating effect on cytochrome oxidase in neurons, even when they have been functionally silenced by TTX.

Aging↗
PubMed1996

Comparative electronmicroscopical investigations on the influences of altered gravity on cytochrome oxidase in the inner ear of fish: a spaceflight study.

The regional metabolic activity in the otolithic sensory epithelia of the inner ear of a cichlid fish (Oreochromis mossambicus) was investigated on light- and electronmicroscopical level using the cytochemical method for detection of cytochrome oxidase activity. In adult animals a characteristic distribution of mitochondria with high enzyme activity was found in sensory and non-sensory cells of otolithic sensory epithelia, which was correlated with regions with a high energy demand. These findings were the basis for studies on the influence of long-term altered gravity conditions in developing larvae: hypogravity (10(-4) g in spaceflight), normal gravity (1 g in a centrifuge in space and 1 g on earth) and hypergravity (3 g in a laboratory centrifuge). Cytochrome oxidase activity was quantified in different parts of the sensory hair cell synapse in the vestibular sensory epithelia utricle and saccule: apical and basal cytoplasm, postsynaptic area of the afferent synapse and presynaptic region of the efferent synapse. Our results show that the energy metabolism of utricle, but not of saccule is decreased after microgravity exposure during the 2nd German Spacelab Mission D-2. However, a general effect of the spaceflight is detectable in both sensory epithelia. Long-term exposure to increased acceleration (3 g) had no effects on cytochrome oxidase activity in inner ear sensory epithelia.

Animals↗
PubMed1991

Reaction of formate with the fast form of cytochrome oxidase: a model for the fast to slow conversion.

The ability to isolate preparations of cytochrome oxidase which are highly homogeneous has facilitated a study of the effects of various reagents on the purified enzyme. The addition of either sodium formate, formamide, formaldehyde, or sodium nitrite to enzyme which reacts in a single rapid kinetic phase with cyanide causes a blue-shift of 4-6 nm of the net (cytochrome a + cytochrome a3) Soret maximum. Only the derivative prepared by adding sodium formate demonstrates measurable intensity in the g' = 12 region of the low-temperature electron paramagnetic resonance (EPR) spectrum. This g' = 12 resonance is characteristic of cytochrome oxidase which has undergone a modification at the binuclear center and thereby reacts sluggishly with cyanide. As the site of cyanide binding in resting enzyme as been demonstrated to be CuB [Yoshikawa, S., & Caughey, W.S. (1990) J. Biol. Chem. 265, 7945-7958], it is proposed that formate can bind to CuB and the fast to slow transition is rationalized by using this proposal. The g' = 12 signal is also produced upon the addition of sodium formate to mitochondrial preparations, suggesting that the species responsible for this behavior may have possible physiological relevance. Physical properties of the formate derivative and data for other reagents reacted with the fast-reacting enzyme preparation are presented.

Animals↗
PubMed1983

Mössbauer study of beef heart cytochrome oxidase. Comparative study of the bovine enzyme and cytochrome c1aa3 from Thermus thermophilus.

We have studied beef heart cytochrome c oxidase at 4.2 K with Mössbauer spectroscopy using the 57Fe present in natural abundance. The spectra observed are very similar to those of the a- and a3-sites of cytochrome c1aa3 from Thermus thermophilus. Thus, many conclusions derived from studies of the bacterial oxidase (available with enriched 57Fe) also apply to the mammalian enzyme. In the resting (as isolated) state, cytochrome a3 of the mammalian enzyme exhibits a doublet with quadrupole splitting, delta EQ = 1.0 mm/s and isomer shift, delta = 0.48 mm/s. These parameters suggest a high spin ferric heme and rule out an Fe(IV) assignment. The absence of magnetic features in the 4.2 K spectrum is consistent with earlier proposals that cytochrome a3 is spin-coupled to a cupric ion. The absorption lines are rather broad, suggesting that the a3-site is heterogeneous in the resting enzyme. Reduced cytochrome a3 has delta EQ = 1.85 mm/s and delta = 0.93 mm/s, demonstrating that the heme iron is high spin ferrous. The observed value for delta EQ is smaller than those of hemoglobin (2.4 mm/s), myoglobin (2.2 mm/s), and cytochrome a3 from T. thermophilus (2.06 mm/s). The Mössbauer spectra of oxidized cytochrome a3-CN show that the heme iron is low spin ferric and that the ground state has integer spin S greater than or equal to 1, which plausibly results from ferromagnetic coupling of the S = 1/2 heme to an S = 1/2 cupric ion. Reduced cytochrome a is low spin ferrous, with parameters similar to those of cytochrome b5 and cytochrome c.

Animals↗
PubMed1997

A mutation in cytochrome oxidase subunit 2 restores respiration of the mutant pet ts1402.

The yeast PET1402/OXA1 gene encoding a 44.8-kDa protein is required for mitochondrial biogenesis. Substitution of Leu240 to serine in the protein results in an accumulation of the precursor form of the mitochondrially encoded subunit 2 of cytochrome oxidase (Cox2) and temperature-sensitive respiration. This temperature sensitivity can be suppressed by a mutation in the cox2 gene changing Ala189 of the Cox2 protein to proline. In the cox2-ts1402 double mutant respiration is restored without removal of the Cox2 pre-sequence. The suppression suggests an interaction of the Pet1402 protein with the cytochrome oxidase complex. Antibodies raised against the predicted C-terminus and the tagged N-terminus of the Pet1402 protein reacted with a 37-kDa polypeptide. This protein, present in the mitochondrial fraction, is localized within the inner membrane. The difference in size can be explained by the removal of the predicted mitochondrial-targeting sequence from the Pet1402 protein. The mitochondrial localization of the protein points to a direct interaction with the cytochrome oxidase complex.

Amino Acid Sequence↗