Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of administration of ethionine on rat liver mitochondrial functions and the protective effect of vitamin E on ethionine induced damage was studied. Ethionine treatment decreased the rate of respiration, respiratory control ratio and P/O ratio. There was a significant decrease in the activities of NADH dehydrogenase, succinate cytochrome C reductase and cytochrome oxidase. A significant decrease was seen on membrane potential and on the levels of ATP. Among the mitochondrial phospholipids only cardiolipin decreased significantly. The lipid peroxide level increased significantly in ethionine treated rats. Administration of vitamin E prior to ethionine treatment relieved the effects (induced by ethionine) on all the parameters studied. This study shows that vitamin E protects against ethionine toxicity.
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PMID:Protective effect of vitamin E against ethionine toxicity. 911 39

Rabbit lung-derived third-stage larvae (L3) of Ascaris suum are aerobic and cyanide sensitive but also contain many enzymes specific to anaerobic pathways. To localize these enzymes, diaminobenzidine (DAB) staining for cytochrome oxidase (COX) and immunogold labeling for 2-methylbutyryl enoyl CoA reductase (ECR) were performed on sections of hypodermis and muscle of adults and larvae of A. suum and visualized by transmission electron microscopy. As predicted, adult hypodermal and muscle mitochondria did not exhibit COX staining; however, hypodermal and muscle mitochondria of the L3 and fourth-stage larvae (L4) were DAB positive. In contrast, hypodermal mitochondria from the adult, L3, and L4 did not exhibit ECR immunoreactivity, whereas mitochondria from muscle of all 3 were ECR positive. These observations suggest that both the ECR and COX are colocalized in muscle mitochondria of the L3.
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PMID:Localization of cytochrome oxidase and the 2-methyl branched-chain enoyl CoA reductase in muscle and hypodermis of Ascaris suum larvae and adults. 926 25

The neurones and microvessels of the dorsal motor nucleus of the vagus (DMN), the nucleus ambiguus (NA) and the nucleus tractus solitarius (NTS) of 4, 24 and 30 month male Wistar rats have been examined morphometrically and by quantitative enzyme histochemical methods (4 and 24 months only) to assess the affects of old age on the structure and activity of their neurones. DMN and NTS neuronal soma area increased whilst NA neuronal area was reduced in the aged groups; the changes in neuronal size were reflected in the density of neurones per unit area. The mean diameter and percentage area occupied by microvessels was unchanged with increased age in all three nuclei. Quantitative assessment of cytochrome oxidase and NADH-tetrazolium reductase activities in the nuclei revealed no changes in old age, indicating that old age does not affect neuronal or metabolic activity of central vagal neurones. These results compliment previous age-related studies on the vagus nerve and nodose ganglion in which little change has been reported, suggesting that the vagal system is well preserved in aged rats.
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PMID:Vagal nuclei in the medulla oblongata: structure and activity are maintained in aged rats. 947 Jan 52

The structural genes for the NO reductase in Paracoccus halodenitrificans, norC, norB, and norQ were sequenced. The norC and norB encode the cytochrome c (NorC) and cytochrome b (NorB) subunits, respectively. The matured NorC (17,258 Da, 148 residues) has a binding motif (CXYCH) for heme c, which is axially coordinated by His65 and Met115. NorB (52,337 Da, 451 residues) has twelve putative transmembrane helices and the 19% sequence homology with the subunit I of cytochrome oxidase from Paracoccus denitrificans. Several histidine and glutamate residues were identified as the ligands for two hemes b and a non-heme iron in comparison with the sequence of cytochrome oxidase. The higher-order model structures constructed from the amino acid sequences of NorC and NorB showed the topology of the helical segments and the locations of the metal centers.
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PMID:Genomic DNA cloning of the region encoding nitric oxide reductase in Paracoccus halodenitrificans and a structure model relevant to cytochrome oxidase. 948 Aug 21

Our previous studies in iron-loaded rat heart cells showed that in vitro iron loading results in peroxidative injury, manifested in a marked decrease in rate and amplitude of heart cell contractility and rhythmicity, which is correctable by treatment with deferoxamine (DF). In the present studies we explored the role of mitochondrial damage in myocardial iron toxicity. Iron loading by 24-hour incubation with 0.36 mmol/L ferric ammonium citrate resulted in a decrease in the activity of nicotinamide adenine dinucleotide (NADH)-cytochrome c oxidoreductase (complex I+III) to 35.3%+/-11.2% of the value in untreated controls; of succinate-cytochrome c oxidoreductase (complex II+III) to 57.4%+/-3.1%; and of succinate dehydrogenase to 63.5%+/-12.6% (p < 0.001 in all cases). The decrease in activity of other mitochondrial enzymes, including NADH-ferricyanide reductase, succinate ubiquinone oxidoreductase (complex II), cytochrome c oxidase (complex IV), and ubiquinol cytochrome c oxidoreductase (complex III), was less impressive and ranged from 71.5%+/-15.8% to 91.5%+/-14.6% of controls. That the observed loss of respiratory enzyme activity was a specific effect of iron toxicity was clearly demonstrated by the complete restoration of enzyme activities by in vitro iron chelation therapy. Sequential treatment with iron and doxorubicin caused a loss of complex I+III and complex II+III activity that was greater than that seen with either agent alone but was only partially correctable by DF treatment. Alterations in cellular adenosine triphosphate measurements paralleled very closely the changes observed in respiratory complex activity. These findings demonstrate for the first time the impairment of cardiac mitochondrial respiratory enzyme activity caused by iron loading at conditions formerly shown to produce severe abnormalities in contractility and rhythmicity.
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PMID:Mitochondrial respiratory enzymes are a major target of iron toxicity in rat heart cells. 960 12

Highly purified tonoplast and plasma membrane vesicles were isolated from microsomes of Arabidopsis thaliana by preparative free-flow electrophoresis. The most electronegative fractions were identified as tonoplast using nitrate-inhibited Mg2+-ATPase as enzyme marker. The least electronegative fractions were identified as plasma membrane using glucan-synthase II, UDPG: sterol-glucosyl-transferase, and vanadate-inhibited Mg2+-ATPase as enzyme markers. Other membrane markers, latent inosine-5'-diphosphatase (Golgi), NADPH-cytochrome-c reductase (endoplasmic reticulum) and cytochrome-c oxidase (mitochondria) were recovered in the fractions intermediate between tonoplast and plasma membrane. Immunoblot analysis of membrane fractions by antibodies directed against tonoplast and plasma membrane proteins confirmed the nature and the purity of the isolated membranes. The cytoskeletal protein actin, which was also identified by immunoblotting, was found to be specifically attached to the plasma membrane vesicles. The structural and functional integrity of the isolated membranes from Arabidopsis thaliana is discussed in the light of results obtained for the location of receptors and enzymes, or for the determination of ligand binding activity.
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PMID:Free-flow electrophoresis for fractionation of Arabidopsis thaliana membranes. 966 77

On the basis of our own experimental data and analysis of data from the literature the existence of nitric oxide cycle in mammals is substantiated. Two components underlie the nitric oxide cycle: 1) the reaction catalyzed by NO-synthases (constitutive, inducible, and endothelial--NOS-I, -II, and -III); and 2) the nitrite-reductase reactions catalyzed by electron-donor systems with the participation of NADH, NADPH, flavoproteins, and heme-containing proteins. In mammalian cells NO is enzymatically formed from terminal guanidine nitrogen of L-arginine by a family of at least three distinct NOS isoenzymes. As a result of nonenzymatic/enzymatic NO oxidation, NO2- and NO3- ions are formed: L-Arg --> NO --> NO2-/NO3-. The reduction of NO2- ions to NO occurs via the nitrite-reductasereaction: NO2- + e- --> NO. The reduction of NO2- ions to NO is realized by electron-donor systems with the participation of NADH, NADPH, flavoproteins, and cytochrome oxidase in mitochondria and by NADH, NADPH, flavoproteins, and cytochrome P-450 in endoplasmic reticulum. In erythrocytes the reduction of NO2- ions to NO is catalyzed by electron-donor systems with participation of NADH, NADPH, flavoproteins, and deoxy-hemoglobin. The role of ascorbic acid and reduced glutathione should be noted among low-molecular-weight compounds. Thus, the presence of the nitric oxide cycle provides the cyclic transformation as follows: L-arginine --> NO --> NO2-/NO3- --> NO.
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PMID:NO-synthase and nitrite-reductase components of nitric oxide cycle. 972 40

A novel, improved method for purification of nitric oxide reductase (NOR) from membranes of Paracoccus denitrificans has been developed. The purified enzyme is a cytochrome bc complex which, according to protein chemical and hydrodynamic data, contains two subunits in a 1:1 stoichiometry. The purified NorBC complex binds 0.87 g of dodecyl maltoside/g of protein and forms a dimer in solution. Similarly, it is dimeric in two-dimensional crystals. Images of these crystals have been processed at 8 A resolution in projection to the membrane. The NorB subunit is homologous to the main catalytic subunit of cytochrome oxidase and is predicted to contain the active bimetallic center in which two NO molecules are turned over to N2O. Metal analysis and heme composition implies that it binds two B-type hemes and a nonheme iron but no copper. NorC is a membrane-anchored cytochrome c. Fourier transform infrared spectroscopy shows that carbon monoxide dissociates from the reduced heme in light and associates with another metal center which is distinct from the copper site of heme/copper oxidases. Electron paramagnetic resonance spectroscopy reveals that NO binds to the reduced enzyme under turnover conditions giving rise to signals near g = 2 and g = 4. The former represents a typical nitrosyl-ferroheme signal whereas the latter is a fingerprint of a nonheme iron/NO adduct. We conclude that the active site of NOR is a dinuclear iron center.
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PMID:The active site of the bacterial nitric oxide reductase is a dinuclear iron center. 974 16

Adriamycin (ADR), a well-known antitumoral drug, interacts with DNA (nuclear and mitochondrial) and cardiolipin. Moreover, ADR induces numerous mitochondrial modifications in sensitive cells. However, no results have yet been obtained as to the repercussions of drug effects on oxido-reductase activities in ADR-resistant cells. To analyze mitochondrial damage induced by ADR treatment, we investigated lactate content, oxygen consumption, respiratory chain activities, and cytochrome content in ADR-sensitive K562 cells and two ADR-resistant variants (K562/R0.2 and K562/R0.5 cells). Biochemical investigations in ADR-resistant cells showed several mitochondrial modifications (in comparison to the parental cell line) according to the variant line and the physiologic state. More particularly, in K562/R0.5 cells cytochrome c (cyt c) oxidase (COX; EC 1.9.3.1) activity and cytochrome aa3 content dramatically decreased since cells enter into the stationary phase. Regardless of the number of multidrug-resistant cell subcultures in ADR-free medium, the cytochrome c oxidase activity in the stationary phase remained unchanged, indicating an irreversible effect of the drug. These alterations could correspond to several modifications of the nuclear and/or mitochondrial genome(s) following acquisition of the ADR resistance phenotype by K562 cells.
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PMID:Modifications of oxido-reductase activities in adriamycin-resistant leukaemia K562 cells. 976 20

To address the problem of the pathogenesis in diabetic neuropathy, rats were made diabetic by streptozotocin administration, and discrete brain regions, such as cortex, cerebellum, brainstem, thalamus, and hypothalamus, were sampled for assay of activities of electron transport chain complexes I-IV at 1 and 3 mo after induction of diabetes. Significant decrease was seen in activities of dinitrophenylhydrazine DNPH-coenzyme Q reductase (complex I), coenzyme Q cytochrome-c reductase (complex III), and cytochrome-c oxidase (complex IV) from discrete brain regions with more pronounced changes in complex I. The decline in the complex I, III, and IV activity was more severe in the 3-mo group. Succinate dehydrogenase (SDH) coenzyme Q reductase (complex II), which is an enzyme shared by tricarboxylic acid (TCA) cycle and electron transport chain, showed a significant increase under the same set of conditions. These results suggest that the bioenergetic impairment has an important role in the pathophysiology of diabetes.
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PMID:The impact of diabetes on CNS. Role of bioenergetic defects. 1034 74


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