Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 trifluoperazine on the respiration of porcine liver and skeletal muscle mitochondria was investigated by polarographic and spectroscopic techniques. Low concentrations of trifluoperazine (88 nmol/mg protein) inhibited both the ADP- and Ca2+-stimulated oxidation of succinate, and reduced the values of the respiratory control index and the ADP/O and Ca2+/O ratio. High concentrations inhibited both succinate and ascorbate plus tetramethyl-p-phenylenediame (TMPD) oxidations, and uncoupler (carbonyl cyanide p-trifluromethoxyphenylhydrazone) and Ca2+-stimulated respiration. Porcine liver mitochondria were more sensitive to trifluoperazine than skeletal muscle mitochondria. Trifluoperazine inhibited the electron transport of succinate oxidation of skeletal muscle mitochondria within the cytochrome b-c1 and cytochrome c1-aa3 segments of the respiratory chain system. 233 nmol trifluoperazine/mg protein inhibited the aerobic steady-state reduction of cytochrome c1 by 92% with succinate as substrate, and of cytochrome c and cytochrome aa3 by 50-60% with ascorbate plus TMPD as electron donors. Trifluoperazine can thus inhibit calmodulin-independent reactions particularly when used at high concentrations.
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PMID:Effect of trifluoperazine on skeletal muscle mitochondrial respiration. 683 Jul 68

A method was developed for selecting cytochrome-deficient mutants of yeast Candida parapsilosis; the method is based on determining the rate of inhibition of oxygen uptake by benzhydroxamic acid, an inhibitor of cyanide-resistant oxidase in the cells of preliminarily obtained yeast mutants. The mutant (C. parapsilosis bhas-1) lacks cytochrome a+a3, contains the same quantity of cytochrome b as the wild strain and a twice as low quantity of cytochrome c. In contrast to the wild strain, the mutant does not grow on ethanol for the first two days but, being cultivated further (up to 5 days), in a medium with ethanol, it resumes its capability to utilize ethanol as a carbon and energy source. Prolonged cultivation in the medium with ethanol induces the biosynthesis of cytochrome oxidase while cytochrome a+a3 is not induced in a medium supplied with glucose. The biomass accumulated by the mutant in the medium with glucose is twice as low comparing to that of the wild strain. The oxidative activity of the mutant mitochondria involves cyanide, resistant oxidase. The mitochondria of the mutant oxidize NAD-dependent substrates, NADH, NADPH, succinate, alpha-glycerophosphate, ethanol and lactate. The mitochondria have a low respiratory control and phosphorylate ADP while oxidizing NAD-dependent substrates, ethanol and lactate, but not alpha-glycerophosphate, succinate, NADH and NADPH.
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PMID:[Selection method and the characteristics of a cytochrome (a+a3)-deficient mutant of Candida parapsilosis yeasts]. 702 49

Mitochondria from skeletal muscle, heart and liver of strain 129/ReJ-dy dystrophic mice and their littermate controls were characterized with respect to their respiratory and phosphorylating activities. Skeletal muscle mitochondria from dystrophic mice showed significantly lower state 3 respiratory rates than controls with both pyruvate + malate and succinate as substrates (P less than 0.01). ADP/O and Ca2+/O ratios were found to be normal. A decreased rate of NADH oxidation (0.01 less than P less than 0.05) by sonicated mitochondrial suspensions from dystrophic mice was also seen. High respiratory rates with ascorbate + phenazine methosulfate as substrates indicated that cytochrome oxidase was not rate limiting in the oxidation of either pyruvate + malate or succinate. Skeletal muscle mitochondria from dystrophic mice showed no deficiency in any of the cytochromes or coenzyme Q. Mg2+-stimulated ATPase activity was higher in dystrophic muscle mitochondria than in controls, but basal and oligomycin-insensitive activities were virtually identical to those of controls. A significant reduction inthe intramitochondrial NAD+ content (0.01 less than P less than 0.02) was seen in dystrophic skeletal muscle as compared to controls. Heart mitochondria from dystrophic mice showed similar, though less extensive abnormalities while liver mitochondria were essentially normal. We concluded from these results that skeletal muscle mitochondria from strain 129 dystrophic mice possess impairments in substrate utilization which may result from (1) an abnormality in the transfer of electrons on the substrate side of coenzyme Q in the case of succinate oxidation; (2) a defect on the path of electron flow from NADH to cytochrome c, and (3) a deficiency of NAD+ in the case of NAD+-linked substrates.
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PMID:Impaired substrate utilization in mitochondria from strain 129 dystrophic mice. 735 83

Several measures of energy conservation, namely ADP/O ratio, P/O ratio, ATP/O ratio and phosphorylation detected by continuous assay with purified firefly luciferase and luciferin, all show phosphorylation can occur with mung-bean mitochondria at cyanide concentrations sufficient to inhibit the cytochrome oxidase system. Phosphorylation in the presence of cyanide is uncoupler- oligomycin- and salicylhydroxamate-sensitive. The participation of phosphorylation site 1 is excluded, phosphorylation being attributable to a single phosphorylation site associated with the cyanide-insensitive oxidase. The cyanide-insensitive oxidase has also been shown to support a variety of other energy-linked functions, namely, Ca2+ uptake, reversed electron transport and the maintenance of a membrane potential detected by the dye probes 8-anilinonaphthalene-1-sulphonate and safranine. High concentrations of cyanide have uncoupler-like activity, decreasing the ADP/O ratio and the t 1/2 for the decay of a pH pulse through the the mitochondrial membrane. This uncoupler-like effect is most marked with aged mitochondria. The observations of energy conservation attributable to the cyanide-insensitive oxidase are compared with other reports where it is concluded that the alternative oxidase is uncoupled.
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PMID:Energy conservation by the plant mitochondrial cyanide-insensitive oxidase. Some additional evidence. 747 54

Respiratory activity and NADH CoQ reductase (complex I) and cytochrome c oxidase (complex IV) activities were measured in free (non-synaptosomal) mitochondria isolated from cerebral cortex of male Balb/c mice exposed to intermittent hypobaric hypoxia (450 Torr; 4300 m) for 21 days and compared to normoxic (sea level) controls. In the hypoxic we found a 47% reduction of oxygen uptake during state 3 (ADP and substrate present), 12% reduction during state 4 (no ADP present) and 20% reduction in the uncoupled respiration rate with pyruvate plus malate as substrates. Respiratory control ratio (RCR) decreased by 24%. No change in the ADP/O ratio was seen. NADH CoQ reductase activity decreased by 30% and cytochrome c oxidase by 17%, suggesting that under conditions of chronic hypoxia, the reductions of mitochondrial respiratory activities are caused, at least in part, by enzymatic alterations of the electron transport chain (complex I and complex IV). The decreased activity of these enzymes could contribute to alterations in neuronal activity by reducing brain energy metabolism during development under conditions of chronic hypoxia.
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PMID:Reduced mitochondrial respiration in mouse cerebral cortex during chronic hypoxia. 747 75

The objective of this study was to assess the relationship between the changes in the redox state of cytochrome oxidase (Cyt. ox.) and those of spontaneous EEG activity and cellular energy state during cerebral ischemia and recirculation. We induced 5-min forebrain ischemia by occluding the bilateral common carotid arteries in anesthetized gerbils. Redox changes of Cyt. ox. were monitored with near-infrared spectroscopy (NIRS) through the experiments. Cortical energy metabolites, ATP, ADP, and AMP, were also measured with high performance liquid chromatography (HPLC) during ischemia and recirculation. Ischemia immediately caused a rapid reduction of Cyt. ox., which paralleled to deterioration of spontaneous EEG activity and preceded significant changes in cellular energy state. Re-oxygenation of Cyt. ox. was observed just after recirculation, and paralleled to the recovery of cellular energy state. Spontaneous EEG activity did not recover even when all other NIRS parameters almost recovered during recirculation after 5-min ischemia. During clamping of the carotid artery, NIRS findings also correlated with those of somatosensory evoked potential (SEP). We concluded that, by means of monitoring redox changes of Cyt. ox., NIRS can detect non-invasively critical neuronal hypoxia prior to a significant impariment of cellular energy state caused by cerebral ischemia, and that NIRS can also detect recovery of oxidative phosphorylation during recirculation, which cannot be observed on EEG.
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PMID:[Near-infrared monitoring of cerebral oxygenation during cerebral ischemia]. 759 May 92

During acute (< 30 min) hypoxia, cellular respiration is independent of the O2 concentration as long as PO2 remains above a critical value (5-10 Torr). Similarly, state 3 respiration by isolated mitochondria is independent of PO2 above a critical tension of 2-4 Torr. However, rat hepatocytes demonstrate a reversible suppression of respiration and an increase in NAD(P)H concentration during prolonged (2-24 h), but not acute hypoxia [P. T. Schumacker, N. Chandel, and A. G. N. Augusti. Am. J. Physiol. 265 (Lung Cell. Mol. Physiol. 9): L395-L402, 1993]. This study tested whether respiration is similarly inhibited in isolated mitochondria exposed to low PO2 for prolonged periods and whether cytochrome-c oxidase participates in this response. Coupled rat liver mitochondria were incubated under low oxygen conditions (PO2 < 2 Torr) for 2 h. State 3 respiration after reoxygenation to PO2 = 20 Torr was then compared with the value obtained subsequently at 100 Torr. Using succinate and ADP as substrates, we determined that state 3 respiration at 20 Torr was 61.0 +/- 8.4% of the subsequent value at 100 Torr (P < 0.05). By contrast, control mitochondria reoxygenated to 100 Torr first and 20 Torr subsequently showed no significant difference at the two O2 tensions (P = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Inhibition of cytochrome-c oxidase activity during prolonged hypoxia. 761 33

Studies from our laboratory have shown that short-term ethanol exposure inhibits epidermal growth factor-dependent replication of cultured fetal rat hepatocytes, along with a drop in ATP level, and that these effects could be caused, at least in part, by ethanol-induced oxidative stress. In these prior studies, mitochondrial morphology was abnormal and membrane lipid peroxidation products were increased, along with reduced transmembrane potential and enhanced permeability to sucrose. To define the effects of ethanol on mitochondrial function further, the present study examines the impact of ethanol exposure on mitochondrial electron transport chain components. A 24-hr exposure of cultured fetal rat hepatocytes to ethanol (2.5 mg/ml) reduced mitochondrial complex I activity by 16% (p < 0.05), complex IV by 28% (p < 0.05), and succinate dehydrogenase by 23% (p < 0.05). This reduction was paralleled by lower ADP translocase activity (24%, p < 0.05) and diminished mitochondrial glutathione (GSH) (20%, p < 0.05). Pretreatment with 0.1 mM S-adenosyl methionine, before ethanol exposure, normalized mitochondrial GSH along with activities of complex I, complex IV, and succinate dehydrogenase. A 3-hr exposure of isolated mitochondria (which do not metabolize ethanol) to ethanol (2.5 mg/ml), inhibited the activities of complex I (19%, p < 0.05), complex IV (24%, p < 0.05), and of ATP synthesis (20%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of acute ethanol exposure on cultured fetal rat hepatocytes: relation to mitochondrial function. 769 41

The partitioning of electrons between the alternative oxidase and the cytochrome pathway of soybean mitochondria has been reassessed in the presence of the alternative oxidase activator pyruvate. In the presence of pyruvate and with succinate as substrate, the alternative oxidase became active at a much lower level of ubiquinone reduction than in the absence of pyruvate. Under state 4 (no ADP present) conditions, activation of the alternative oxidase with pyruvate resulted in an oxidation of b cytochromes, demonstrating switching of electrons away from the cytochrome chain. In the presence of ferricyanide and the cytochrome oxidase inhibitor KCN, cytochrome chain activity could be followed spectrophotometrically and that of the alternative pathway with an oxygen electrode. Under these conditions, the addition of pyruvate diverted electron flow from the cytochrome chain to the alternative pathway; subsequent inhibition of the alternative oxidase increased electron flow via the cytochrome chain. This indicates that electrons can be switched from one pathway to the other when the cytochrome chain is not saturated and this was confirmed by n-propylgallate titrations (p plots) of mitochondria oxidizing succinate. Decreases in ADP/O ratios and phosphorylation rate upon addition of pyruvate indicated that the alternative pathway could also contribute to respiration under state 3 conditions. The results indicate that when the alternative oxidase is activated by pyruvate, it can compete for electrons with the cytochrome chain and does not act as an overflow pathway. The significance of these observations for in vivo respiration is discussed.
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PMID:Cytochrome and alternative respiratory pathways compete for electrons in the presence of pyruvate in soybean mitochondria. 773 68

The energy metabolism was evaluated in gastrocnemius muscle from 3-month-old rats subjected to either mild or severe 4-week intermittent normobaric hypoxia. Furthermore, 4-week treatment with CNS-acting drugs, namely, alpha-adrenergic (delta-yohimbine), vasodilator (papaverine, pinacidil), or oxygen-increasing (almitrine) agents was performed. The muscular concentration of the following metabolites was evaluated: glycogen, glucose, glucose 6-phosphate, pyruvate, lactate, lactate-to-pyruvate ratio; citrate, alpha-ketoglutarate, succinate, malate; aspartate, glutamate, alanine; ammonia; ATP, ADP, AMP, creatine phosphate. Furthermore the Vmax of the following muscular enzymes was evaluated: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; citrate synthase, malate dehydrogenase; total NADH cytochrome c reductase; cytochrome oxidase. The adaptation to chronic intermittent normobaric mild or severe hypoxia induced alterations of the components in the anaerobic glycolytic pathway [as supported by the increased activity of lactate dehydrogenase and/or hexokinase, resulting in the decreased glycolytic substrate concentration consistent with the increased lactate production and lactate-to-pyruvate ratio] and in the mitochondrial mechanism [as supported by the decreased activity of malate dehydrogenase and/or citrate synthase resulting in the decreased concentration of some key components in the tricarboxylic acid cycle]. The effect of the concomitant pharmacological treatment suggests that the action of CNS-acting drugs could be also related to their direct influence on the muscular biochemical mechanisms linked to energy transduction.
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PMID:Modifications by chronic intermittent hypoxia and drug treatment on skeletal muscle metabolism. 778 38


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