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[Succinate dehydrogenase and cytochrome oxidase activity in rat tissues during prolonged hypokinesia].

The activity of cytochrome oxidase in the liver, skeletal muscles, kidneys, brain and lungs of 56 white rats decreased on days 15 and 60 of the hypokinetic study. The activity of succinate dehydrogenase significantly lowered in the brain and slightly diminished in the lungs and skeletal muscles on the same days. The activity of succinate dehydrogenase in the liver increased on the 90th hypokinetic day.

Animals↗
PubMed1987

Immunological and spectral characterization of partly purified cytochrome oxidase from the cyanobacterium Synechocystis 6714.

Membranes were isolated by French pressure cell extrusion of lysozyme-preincubated cells of the cyanobacterium Synechocystis 6714 after growth in the presence of 0.4 M NaCl for 4 days. These cells showed up to 6-fold respiratory activity (oxygen uptake) when compared to control cells. Separation of plasma and thylakoid membranes revealed that the major part of cytochrome c oxidase was associated with the latter. Immunoblotting of sodium dodecylsulfate polyacrylamide gel electrophorized membranes with antisera raised against subunit I, subunit II, and the holoenzyme of the aa3-type cytochrome oxidase from Paracoccus denitrificans gave specific and complementary cross-reactions at apparent molecular weights of about 25 and 17-18 kDa, respectively. Crude membranes were solubilized also with n-octyl glucoside, and the cytochrome oxidase was separated from the extract by affinity chromatography using immobilized cytochrome c from Saccharomyces cerevisiae. The enzyme was eluted with KCl/octyl glucoside. Dialysed and concentrated enzyme solution, which was free of b- and c-type cytochromes, gave reduced alpha- and gamma-peaks around 603 and 443 nm, respectively. Upon treatment of the sample with carbon monoxide the peaks were found at 593 and 433 nm, respectively. Photodissociation spectra of the CO-complexed enzyme were in full agreement with cytochrome aa3 being a functional cytochrome oxidase in Synechocystis 6714.

Cell Membrane↗
PubMed1997

6-Ketocholestanol is a recoupler for mitochondria, chromatophores and cytochrome oxidase proteoliposomes.

The effect of 6-ketocholestanol (kCh) on various natural and reconstituted membrane systems has been studied. 6-ketocholestanol (5 alpha-Cholestan-3 beta-ol-6-one), a compound increasing the membrane dipole potential, completely prevents or reverses the uncoupling action of low concentrations of the most potent artificial protonophore SF6847. This effect can be shown in the rat liver and heart muscle mitochondria, in the intact lymphocytes, in the Rhodobacter sphaeroides chromatophores, and in proteoliposomes with the heart muscle or Rh. sphaeroides cytochrome oxidase. The recoupling effect of kCh disappears within a few minutes after the kCh addition and cannot be observed at all at high SF6847 concentrations. Almost complete recoupling is also shown with FCCP, CCCP, CCP and platanetin. With 2,4-dinitrophenol, fatty acids and gramicidin, kCh is ineffective. With TTFB, PCP, dicoumarol, and zearalenone, low kCh concentrations are ineffective, whereas its high concentrations recouple but partially. The kCh recoupling is more pronounced in mitochondria, lymphocytes and proteoliposomes than in chromatophores. On the other hand, mitochondria, lymphocytes and proteoliposomes are much more sensitive to SF6847 than chromatophores. A measurable lowering of the electric resistance of a planar bilayer phospholipid membrane (BLM) are shown to occur at SF6847 concentrations which are even higher than in chromatophores. In BLMs, kCh not only fails to reverse the effect of SF6847, but even enhances the conductivity increase caused by this uncoupler. It is assumed that action of low concentrations of the SF6847-like uncouplers on coupling membranes involves cytochrome oxidase and perhaps some other membrane protein(s) as well. This involvement is inhibited by the asymmetric increase in the membrane dipole potential, caused by incorporation of kCh to the outer leaflet of the membrane.

Adenosine Triphosphate↗
PubMed1981

Mitochondrial number, cytochrome oxidase and succinic dehydrogenase activity in Xenopus laevis oocytes.

An estimate has been made of the numbers of mitochondria in the mitochondrial cloud (Balbiani body) of Xenopus laevis oocytes ranging in size from 50 to 250 micrometers. The mitochondrial number is expressed in terms of a 'standard' organelle measuring 2 micrometers in length and 0.2 micrometer in diameter and is derived by measurements on electron micrographs of sections through the cloud. It is found that the amount of mitochondrial material rises very rapidly as the oocyte grows in size. At the time the cloud disperses, in oocytes of about 300 micrometers in diameter, it is estimated that there are the equivalent of over 500 000 mitochondria in each cell. The rate of increase is very similar to the rate of accumulation of mitochondrial DNA during the same period of growth. Using a polarographic technique the specific activity of cytochrome oxidase and succinic dehydrogenase was determined in mitochondrial fractions isolated from oocytes over a size range of 80-1200 micrometers in diameter. Although the specific activity of succinic dehydrogenase remains constant that of cytochrome oxidase falls sharply during the period when the mitochondria are replicating rapidly, i.e. up to about 300 micrometer diameter. In larger oocytes the specific activity of enzymes appears to remain constant but increasing contamination of the isolated mitochondrial fraction does not allow conclusions to be drawn from the enzyme loading of the mitochondria once they have dispersed from the cloud. The results are discussed in relation to the possibility that mitochondrial replication preceeds, or at least outpaces, mitochondrial differentiation during the course of oogenesis.

Animals↗
PubMed2004

The bacterial cytochrome cbb3 oxidases.

Cytochrome cbb(3) oxidases are found almost exclusively in Proteobacteria, and represent a distinctive class of proton-pumping respiratory heme-copper oxidases (HCO) that lack many of the key structural features that contribute to the reaction cycle of the intensely studied mitochondrial cytochrome c oxidase (CcO). Expression of cytochrome cbb(3) oxidase allows human pathogens to colonise anoxic tissues and agronomically important diazotrophs to sustain N(2) fixation. We review recent progress in the biochemical characterisation of these distinctive oxidases that lays the foundation for understanding the basis of their proposed high affinity for oxygen, an apparent degeneracy in their electron input pathways and whether or not they acquired the ability to pump protons independently of other HCOs.

Bacteria↗
PubMed1990

Chronological observations of histological changes, cytochrome oxidase activity and copper level in the brain of the postnatal brindled mouse.

Neuropathological and enzyme-histochemical studies were performed on brindled mouse hemizygotes (BMs) and normal littermates at the age of 2 days, 7 days, 11 days and 14 days, together with an investigation of their tissue copper levels. A greatly increased copper concentration was confirmed in the kidney and intestine and a greatly reduced concentration in the liver and brain of BMs. The copper concentration in the brain increased gradually with age in the normal littermates, whereas this did not occur in BMs. There was no significant difference in the tissue copper concentration between the cerebrum and the cerebellum-brainstem in BMs or in normal littermates. Light and electron microscopy of the BM brain revealed progressive neuronal degeneration in association with increased mitochondrial changes (ballooning and crista disintegration). Enzyme histochemical examinations demonstrated a progressive comparative decrease (i.e., an increased difference from normal) of cytochrome oxidase activity in the BM brain. These data suggest that progressive degeneration of the brain in Menkes' disease is attributable to mitochondrial degeneration caused by a comparative decrease of both copper concentration and cytochrome oxidase activity in the brain.

Animals↗
PubMed1996

Quantitative analysis of vascularization and cytochrome oxidase following fetal transplantation in the contused rat spinal cord.

In the normal adult central nervous system, a coupling between energy consumption and vascular density is well established. Likewise, the survival of fetal neural tissue grafts is highly dependent on the establishment of functional vascular integration with the host. However, to what degree graft vascularization and tissue metabolism influence the normal host response to traumatic injury has not been extensively studied. In the present report, embryonic day 14 fetal spinal cord suspension grafts were made into the lesion epicenter of subchronic (10 days) contusion-injured rats. Three months later, intraspinal transplants were analyzed using correlative cytochrome oxidase histochemistry and vascular morphometric analysis. The same approaches were applied to the host spinal cord and injured, non-transplanted animals in order to determine the ability of a graft to alter the level of post-injury vascularization and/or metabolism. In general, graft vascular density was increased over that measured in normal or injured gray matter. Vascular density in gray matter near the host/graft interface was markedly increased when compared to either gray matter of the same spinal level in injured non-grafted animals or normal control spinal gray matter. Vascular changes were not noted in gray matter 3 mm distal to the lesion epicenter (rostral or caudal) in all groups analyzed. Cytochrome oxidase was up-regulated at this time in the graft and gray matter at the host/graft interfaces when compared to either gray matter of the same spinal level in injured, non-grafted animals or that of uninjured controls. These data indicate that an intraspinal transplant placed into the contused adult rat spinal cord reaches a metabolic capacity that is likely to be associated with high levels of oxidative metabolism in the well-vascularized graft neuropil. In addition, transplantation chronically alters vascularization and metabolic patterns of adjacent spinal gray matter following contusion injury.

Animals↗
PubMed1993

Insight into the active-site structure and function of cytochrome oxidase by analysis of site-directed mutants of bacterial cytochrome aa3 and cytochrome bo.

Cytochrome aa3 of Rhodobacter sphaeroides and cytochrome bo of E. coli are useful models of the more complex cytochrome c oxidase of eukaryotes, as demonstrated by the genetic, spectroscopic, and functional studies reviewed here. A summary of site-directed mutants of conserved residues in these two enzymes is presented and discussed in terms of a current model of the structure of the metal centers and evidence for regions of the protein likely to be involved in proton transfer. The model of ligation of the heme a3 (or o)-CuB center, in which both hemes are bound to helix X of subunit I, has important implications for the pathways and control of electron transfer.

Amino Acid Sequence↗
PubMed2002

[The effect of extremely low frequency magnetic fields on cytochrome oxidase subunit 1 mRNA transcription].

OBJECTIVE: To clone and identify MF-1 gene which responded to extremely low frequency magnetic fields(ELF MF) in Daudi cells, and explore the response universality of MF-1 gene in several MF-sensitive cell lines, so as to provide experimental basis for revealing the mechanism of biological effects induced by magnetic field. METHODS: The DNA fragment of MF-1 was cloned and sequenced; the mRNA level of MF-1 gene were analysed in MF-sensitive cell lines(HL-60, L1210 and CHL) by Northern blot after these cells being treated with 0.1 mT and 0.8 mT MF for 20 minutes and 24 hours, respectively. RESULTS: The MF-1 cDNA sequence had 100% homology with cytochrome oxidase subunit 1 gene(CO1) by searching Gene Bank database; the transcription of CO1 in HL-60, L1210 and CHL cell lines which exposed to 0.1 mT and 0.8 mT MF for 20 minutes were significantly lower(0.38 +/- 0.12 and 0.37 +/- 0.04) than that of control(0.58 +/- 0.12) and so did for 24 hours exposure(0.46 +/- 0.09 and 0.45 +/- 0.09 vs 0.65 +/- 0.06) (P < 0.05). CONCLUSION: CO1 is a MF-responsive gene. Cytochrome oxidase activity may be affected through low level of CO1 transcription by magnetic fields, thus induce bioeffects in organisms.

Animals↗
PubMed1991

Relationship between appearance of GABA, fluorogenic monoamines and cytochrome oxidase activity during prenatal morphogenesis of chick myenteric plexus.

The basic histology of the developing embryonic gut wall of the chick was examined on haematein and eosin-stained paraffin sections. In parallel with this, the ontogenic sequence of myenteric plexus formation was followed on whole mounts after NADH diaphorase histochemistry. The presence of nerve elements was verified also by electron microscopy. The appearance of enteric gamma-aminobutyric acid-containing neurons, as an example of an intrinsic inhibitory neuronal system, was studied by using an antiserum against the gamma-aminobutyric acid glutaraldehyde bovine serum albumin conjugate. The development of noradrenergic innervation as an extrinsic inhibitory supply was followed by means of a glyoxylic acid-induced fluorescence method. Cytochrome oxidase activity was detected histochemically. Three consecutive steps of the morphogenesis of the myenteric plexus were revealed; first the appearance of a cellular crest at the mesenteric border on embryonic day 9; second the migration and clustering of nerve cells between embryonic days 10 and 16; then the elongation of neurites on embryonic days 16 and 21. Immunoreactive and also fluorescent fibres were first detected on the 14th day of incubation, while immunopositive cell bodies appeared only after hatching. In the early stages the cytochrome oxidase activity was restricted to the perikarya, while at the end of embryonic development the activity also appeared in the ganglionic neuropile. On the basis of these observations, we concluded that there is a close time relation between the morphogenesis and the biochemical and functional maturation of the myenteric plexus.

Animals↗
PubMed1993

Immunocytochemical and histochemical analyses of gonadotrophin releasing hormone, tyrosine hydroxylase, and cytochrome oxidase reactivity within the hypothalamus of chicks showing early sexual maturation.

In order to determine the changes in gonadotrophin releasing hormone (GnRH) and dopaminergic activity within the brain during the onset of sexual precocity, a Halasz-like knife was developed to produce discrete parasagittal cuts in 2-week-old male broiler chicks. At 5 weeks of age, sexually precocious respondents were selected on the basis of advanced secondary sex characteristics and randomly paired with sham-operated controls. Each pair of birds was perfused with heparinized saline followed by 4% paraformaldehyde. Sections 40 microns thick, obtained throughout the hypothalamus, were immunostained with either anti-GnRH or anti-tyrosine hydroxylase (TH) to ascertain dopaminergic activity. Alternate sections from each pair of brains were also treated with cytochrome oxidase to determine metabolic activity levels or with Nissl stain to localize the knife cuts. Analysis revealed an increase in GnRH immunoreactivity within the bed nucleus of the pallial commissure (nCPa) and paraventricular nucleus (PVN), as well as the median eminence (ME). An increase in TH immunoreactivity was observed in the nucleus intramedialis (nI). Also an increase in metabolic activity was seen in the PVN as revealed by cytochrome oxidase reactivity. It is hypothesized that during the onset of puberty there is an increase in immunoreactive GnRH cell numbers as a result of a decrease in the inhibition of the GnRH system, possibly involving the nI and PVN. The source of the dopamine reported in the ME could be from the nI and other nearby nuclei. Dopamine from the tubero-infundibular area may be one of the putative neurotransmitters responsible for the increased activity of GnRH within the ME of chicks showing precocious puberty.

Animals↗
PubMed1991

Cytochrome oxidase induction after oxidative stress induced by adriamycin in liver of rats fed with dietary olive oil.

The influence of different kinds of dietary fat (8%) and of endogenous lipid peroxidation with regard to cytochrome c oxidase activity and cytochrome a + a3 concentrations in mitochondria from rat liver has been investigated. It was possible to confirm that the dietary fat induced higher phospholipid degradation in mitochondrial membranes; moreover an endogenous oxidative stress induced by adriamycin was able to increase the peroxidative effects. We have found that the peroxidative effects could sometimes induce an apparent enhancement of cytochrome oxidase activity due to a significant increase of cytochrome a + a3 content. This finding lets us suppose that both changes in the lipid environment and some peroxidation damage could occur in the membrane as a consequence of the fat assumed. Furthermore we should suggest that an induction of the synthesis of cytochrome a + a3 might be related to an enhanced production of peroxides at membrane level.

Animals↗
PubMed1983

[Redox-dependent protonation of cytochrome oxidase hemes in submitochondrial particles of the bovine heart].

Potentiometric titrations of cytochrome oxidase in bovine heart submitochondrial particles were carried out within the pH range 5.3-9.0 in the alpha-band of heme absorption. The data obtained were analyzed within a model of non-interacting hemes and in accordance with a "neoclassical" scheme implying heme--heme interactions between cytochromes a and a3. The individual pH-dependencies of half-reduction potentials of cytochromes a and a3 were determined. It was found that the redox-dependent protonation (the oxidation Bohr effect) is characteristic of the both cytochromes; however, the reduction of one of the hemes significantly diminishes the Bohr effect for the second heme. The redox transitions of cytochrome a are coupled to ionization of at least two heme-linked acid-base groups of the enzyme with pK1(red) in the acidic and pK2(ox) in the alkaline regions of pH, whereas the pH dependence of E0' for cytochrome a3 fits to the model containing one hemi-linked group with a pKred in the acidic region.

Animals↗
PubMed2004

Dynamics of electron transfer pathways in cytochrome C oxidase.

Cytochrome c oxidase mediates the final step of electron transfer reactions in the respiratory chain, catalyzing the transfer between cytochrome c and the molecular oxygen and concomitantly pumping protons across the inner mitochondrial membrane. We investigate the electron transfer reactions in cytochrome c oxidase, particularly the control of the effective electronic coupling by the nuclear thermal motion. The effective coupling is calculated using the Green's function technique with an extended Huckel level electronic Hamiltonian, combined with all-atom molecular dynamics of the protein in a native (membrane and solvent) environment. The effective coupling between Cu(A) and heme a is found to be dominated by the pathway that starts from His(B204). The coupling between heme a and heme a(3) is dominated by a through-space jump between the two heme rings rather than by covalent pathways. In the both steps, the effective electronic coupling is robust to the thermal nuclear vibrations, thereby providing fast and efficient electron transfer.

Computer Simulation↗
PubMed1976

Studies on cytochrome oxidase. Preliminary characterization of an enzyme containing only four subunits.

The preparation of a four-subunit enzyme from yeast, capable of catalyzing the oxidation of ferrocytochrome c, is described. It is derived from proteins containing seven or five subunits by means of recycling exclusion chromatography in the presence of 0.1% sodium dodecyl sulfate. Its catalytic properties are similar to those of the parent enzyme. Gel electrophoresis of this preparation in the presence of sodium dodecyl sulfate reveals three bands, migrating with RF values that correspond to molecular weights of 14.6, 12.3, and 10.6 X 10(3), with the largest exhibiting an apparent 2:1 stoichiometry relative to the other two. Visible spectra in the region of 390 to 630 nm do not show any detectable difference from that of the parent cytochrome oxidase, while its heme a and copper content are raised to values around 20 nmol or ng atoms/mg of protein, respectively, corresponding to minimal molecular weights of 50 X 10(3). The molecular weight determined by physical means equals 107 X 10(3). Thus the enzyme probably contains two copies of each subunit. After extensive dialysis to remove as much as possible of the sodium dodecyl sulfate used in its preparation, this enzyme remains in solution in phosphate buffer in the absence of any added detergent, while under similar conditions the seven-subunit complex precipitates completely. A similar preparation can also be obtained from beef heart. The significance of these findings is discussed with respect to the role of the large subunits in the function as well as the biogenesis of the mitochondrial cytochrome oxidase complex.

Animals↗
PubMed1991

Proton interactions in the resting form of cytochrome oxidase.

The effect of pH on the near-UV absorption spectrum of cytochrome oxidase has been examined. Several lines of evidence implicate a proton binding site that can modulate the optical properties of cytochrome alpha 3 in the resting enzyme. Changing the pH within the range 6.5-10.5 was found to reversibly shift the position of the Soret band over an 11-nm range. The lower pH values caused a progressive blue shift in the Soret band, whereas the high-pH range promoted a gradual red shift. Limiting band positions were approximately 416 and 427 nm. The incubation time required to reach a stable band position varied somewhat as did the actual extent of the shift. In most cases, the shift was associated with an isosbestic point. A pH titration profile for the apparent equilibrium position of the Soret band was obtained. Nonlinear least-squares fitting to a scatter plot, assuming a single acid/base group, showed an apparent pKa of 7.8. Magnetic circular dichroism (MCD) spectra of the low-pH form at 416 nm, the high-pH form at 427 nm, and the cyanide derivative at 428 nm were compared. No evidence of a high-pH-dependent low-spin transition or a change in the redox state of cytochrome a3 was found, confirming earlier work [Baker, G. M., Noguchi, M., & Palmer, G. (1987) J. Biol. Chem. 262, 595-604]. Subtraction of ferricytochrome a [spectrum taken from Vanneste, W. H. (1966) Biochemistry 5, 838-848] from a series of blue-shifting spectra showed a band at 414 nm that progressively gained amplitude and a band at 430 nm that correspondingly lost amplitude. A series of red-shifting spectra showed the opposite behavior with a clear isosbestic point being evident in both cases. The difference extinction change at 414 and 430 nm depended linearly on the position of the Soret band, both showing a reversible dependence on pH. The 430-nm band is noted to be unusually red-shifted for high-spin ferric heme a. An additional, pH-insensitive band was observed at 408-410 nm which was eliminated by treatment with cyanide. The kinetics of the pH-induced blue shift and red shift were obtained at 416 nm by using dual-wavelength method and found to be biphasic, despite the occurrence of an isosbestic point.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Antibodies as probes of cytochrome oxidase structure and function.

Antibodies have been raised in rabbits against whole beef heart cytochrome oxidase and against purified subunit V. Western blot analysis showed that antioxidase was largely composed of anti-II and anti-IV antibodies but some anti-I and antibodies against small subunits were elicited. Similar analysis of anti-V showed it to be relatively specific against subunit V. Three types of anti-V were identified by ELISA with intact enzyme: (i) weak binding and redox independent, (ii) stronger binding, redox-dependent (binding only to reduced or partially reduced enzyme), and membrane-independent, and (iii) moderate-binding, redox-dependent & membrane-dependent. Inhibition of enzyme activity by anti-oxidase was biphasic in time, indicating populations of rapidly- and slowly- reacting molecules. Variation of cytochrome c concentration showed partially competitive kinetics, but the antibody also affected 'internal' enzymatic events including the turnover rate with TMPD and the spin-state change in cytochrome a3 that follows reduction of cytochrome a. No spectral effects could however be seen. Antioxidase also inhibits proteoliposomal respiration with external cytochrome c but not that with internally-trapped cytochrome c. No functionally significant epitopes occur on the N (matrix) side of the membrane. The more strongly binding anti-V inhibits the isolated enzyme by at least 60%. The inhibition at high ionic strength induces a biphasic pattern with respect to cytochrome c concentration. Anti-V may thus slow the dissociation of cytochrome c from its complex with the enzyme. The redox-dependent, membrane-dependent anti-V (reported previously) gave only about 20% inhibition of the enzyme. The effective anti-V antibody had little if any influence on the activity of proteoliposomal oxidase in either orientation. Some sites on subunit V whose binding can give rise to inhibition are not accessible to anti-V when the enzyme is embedded in a functional membrane system.

Animals↗
PubMed1987

The distance between cytochromes a and a3 in the azide compound of bovine-heart cytochrome oxidase.

The electron-spin relaxation rates of the two species of cytochrome a3(3+)-azide found in the azide compound of bovine-heart cytochrome oxidase were measured by progressive microwave saturation at T = 10 K. It has been shown previously that Cyt a3(3+)-azide gives rise to two distinct EPR resonances, depending upon the oxidation state of Cyt a. When Cyt a is ferrous, Cyt a3(3+)-azide has g = 2.88, 2.19 and 1.64; upon oxidation of Cyt a, the a3(3+)-azide g-values become g = 2.77, 2.18, and 1.74 (Goodman, G. (1984) J Biol. Chem. 259, 15094-15099). The relaxation effect of Cyt a on Cyt a3 could be measured as the difference in microwave field saturation parameter H1/2 between the g = 2.77 and g = 2.88 species. For each signal the spin-lattice relaxation time T1 was determined from H1/2 using the transverse relaxation time T2. The value of T2 at 10 K was extrapolated from a plot of line-width vs. temperature at higher temperature. The dipolar contribution to T1 was related to the Cyt a-Cyt a3 spin-spin distance utilizing available information on the relative orientation of Cyt a3-azide and Cyt a (Erecińska, M., Wilson, D.F. and Blasie, J.K. (1979) Biochim. Biophys. Acta 545, 352-364). By taking into account the relaxation parameters for both gx and gz components of the Cyt a3-azide g-tensor, the angle between the gz components of the Cyt a and Cyt a3 g-tensors was determined to be between 0 and 18 degrees, and the Cyt a-Cyt a3 spin-spin distance was found to be 19 +/- 8 A.

Anaerobiosis↗