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)

Oxidized dialdehyde analogs of ADP or ATP (oADP and oATP) were shown to inhibit irreversibly adenine nucleotide translocator (T) and creatine kinase (CK) in heart mitochondria. Inactivation of T and CK was parallel with carboxyatractyloside - sensitive and (ADP + phosphocreatine) - sensitive incorporation of o[3H]ADP into mitochondria, respectively. o[3H]ADP incorporation sensitive to CAT or ADP+phosphocreatine was used to determine T and CK contents in mitochondria. T content in cardiac mitochondria from rat, rabbit, dog, and chicken was calculated to be 2.6 - 2.9 moles/mole cyt.aa3. The same value of T/cyt.aa3 ratio was found in liver mitochondria with lower cytochrome aa3 content. In all types of cardiac mitochondria CK content was found to be 2.4 - 2.6 moles/mole cyt.aa3. The data show that T and CK are present in molar ratio 1:1 in all types of cardiac mitochondria.
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PMID:Affinity modification of creatine kinase and ATP-ADP translocase in heart mitochondria: determination of their molar stoichiometry. 300 38

Cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1), as the terminal enzyme of the mammalian mitochondrial electron transport chain, has long been known to catalyze the reduction of dioxygen to water. We have found that when reductively activated in the presence of dioxygen, the enzyme will also catalyze the oxidation of carbon monoxide to its dioxide. Two moles of carbon dioxide is produced per mole of dioxygen, and similar rates of production are observed for 1- and 2-electron-reduced enzyme. If 13CO and O2 are used to initiate the reaction, then only 13CO2 is detected as a product. With 18O2 and 12CO, only unlabeled and singly labeled carbon dioxide are found. No direct evidence was obtained for a water-gas reaction (CO + H2O----CO2 + H2) of the oxidase with CO. The CO oxygenase activity is inhibited by cyanide, azide, and formate and is not due to the presence of bacteria. Studies with scavengers of partially reduced dioxygen show that catalase decreases the rate of CO oxygenation.
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PMID:Oxygenation of carbon monoxide by bovine heart cytochrome c oxidase. 300 48

We have found here that there are clear structural requirements for peroxisome proliferation (monitored as increases in carnitine acetyltransferase activity, cyanide-insensitive palmitoyl-CoA oxidation, catalase and increases in the protein designated PPA 80) in mouse liver. From the investigation of ten structural analogues of 2-ethylhexanoic acid, it could be concluded that the most effective proliferators all have an ethyl group as the substituent on carbon 2 of the main chain, which consists of six carbons. The further observation from this group of compounds that a charged group is required for effective proliferation leads us to speculate that such a group is involved in the molecular mechanism as well. Many, but not all, of the effective peroxisome proliferators in a second group of compounds contain a phenoxy group, often with a substituted alpha carbon. Interestingly, the 2,4-dichlorophenoxyacetic and 2,4,5-trichlorophenoxyacetic acids are both effective peroxisome proliferators, but the closely related p-chlorophenoxyacetic acid is inactive in this respect, indicating that the chlorine atom at position 2 must be essential to the process in these cases. The results presented here also indicate that the structural requirements for proliferation of mitochondria are similar to those for proliferation of peroxisomes. Certainly, the most effective peroxisome proliferators also cause large increases in 'mitochondrial' protein and cytochrome oxidase activity, i.e. there is an obvious qualitative correlation.
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PMID:Examination of the structural requirements for proliferation of peroxisomes and mitochondria in mouse liver by hypolipidemic agents, with special emphasis on structural analogues of 2-ethylhexanoic acid. 302 4

As a first step in studies of the molecular mechanism(s) underlying gentamicin toxicity, rat kidney cortex has been subfractionated using differential centrifugation. An analytical, rather than preparative approach was used. DNA was used as a marker for the nuclei, cytochrome oxidase for mitochondria, acid phosphatase for lysosomes, catalase for peroxisomes, NADPH-cytochrome c reductase for the endoplasmic reticulum, p-nitrophenyl-alpha-mannosidase (at pH 5.5) for the Golgi apparatus, AMPase for the plasma membrane in general, and alkaline phosphatase for the brush border, and lactate dehydrogenase for the cytosol. In addition, electron microscopy was performed on the subfractions obtained. The distributions of subcellular markers obtained here for the rat kidney cortex closely resemble the corresponding distributions reported for rat liver. This procedure can now be used to look for biochemical and/or toxic changes which might be reflected in an altered distribution pattern for marker enzymes.
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PMID:Biochemical effects of gentamicin on rat kidney cortex. I. Analytical subfractionation of control tissue. 303 Jul 99

As a first step in studies on the molecular mechanism(s) underlying gentamicin toxicity, the effect of treating rats with this aminoglycoside antibiotic (100 mg/kg once or twice daily for 3 days) on the analytical subfractionation of the kidney cortex has been examined. DNA was used as a marker for the nuclei, cytochrome oxidase for mitochondria, acid phosphatase for lysosomes, catalase for peroxisomes (with reservations; see the companion paper), NADPH-cytochrome c reductase for the endoplasmic reticulum, p-nitrophenyl-alpha-mannosidase (at pH 5.5) for the Golgi apparatus, AMPase for the plasma membrane in general and alkaline phosphatase for the brush border, and lactate dehydrogenase for the cytosol. In addition, the presumptive lysosomal hydrolases N-acetyl-beta-D-glucosaminidase, p-nitrophenyl-alpha-mannosidase (at pH 4.5), cathepsin D, and DNase II were monitored. Electron microscopy was also performed on the subfractions obtained. The only significant biochemical changes brought about by gentamicin treatment were that N-acetyl-beta-D-glucosaminidase demonstrated both a greater total activity and a larger enrichment in the 104,000gav pellet, while p-nitrophenyl-alpha-mannosidase at pH 4.5 demonstrated the same total activity and a greater enrichment in the 104,000gav pellet. Since myeloid bodies were shown by electron microscopy to sediment primarily with the 500gav and 10,000gav pellets, the biochemical changes seen cannot be associated with these morphological structures. These findings suggest that selective changes in a certain subpopulation(s) of lysosomes or in certain lysosomal enzymes may be involved in the early stages of gentamicin toxicity. On the other hand, no lysosomal membrane damage was observed here, since both the latency of acid phosphatase and the recovery of this activity in the soluble cytosol were unchanged. The present investigation may also have relevance for the dosage and duration of gentamicin treatment chosen in clinical situations.
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PMID:Biochemical effects of gentamicin on rat kidney cortex. II. Analytical subfractionation after short-term, high-dose treatment. 303 Aug

Manganous (Mn) and copper zinc (CuZn) superoxide dismutase (SOD) concentrations and glutathione peroxidase (GSH-Px) and catalase (CAT) activities were measured in cultured bovine pulmonary endothelial cells with and without exposure to Escherichia coli endotoxin (10(-1) micrograms/ml) over intervals of 0.5-24 h. The activities of two mitochondrial marker enzymes, fumarase and cytochrome-c oxidase, were also measured. Endotoxin exposure caused a marked increase (9-fold) in endothelial cell Mn SOD content without significant effects on GSH-Px, CAT, fumarase, or cytochrome-c oxidase activities. Endotoxin induced a slight decrease in CuZn SOD content over 24 h. This is the first report of a selective effect of endotoxin on Mn SOD in pulmonary endothelial cells. The response appears to be independent of an increase in mitochondrial activity (no change was observed in cytochrome-c oxidase or fumarase activities). These findings support the notion that endotoxin increases generation of toxic oxygen metabolites within pulmonary endothelial cells. An endotoxin-induced increase in Mn SOD could contribute to the reported protective effect of endotoxin against oxygen toxicity in these cells.
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PMID:Endotoxin increases superoxide dismutase in cultured bovine pulmonary endothelial cells. 303 89

The effects of dietary exposure to 0.125% (w/w) p-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid or 2,4,5-trichlorophenoxyacetic acid on the content of peroxisomes and levels of certain xenobiotic-metabolizing enzymes in mouse liver have been investigated. In agreement with the literature on rat liver 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid were found to cause extensive proliferation of peroxisomes (as judged by the total levels of "mitochondrial" protein, carnitine acetyltransferase, cyanide-insensitive palmitoyl-CoA oxidation and catalase) in mouse liver. On the other hand, exposure to p-chlorophenoxyacetic acid did not significantly affect any of these parameters. As with certain other peroxisome proliferators, 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid increased total cytochrome oxidase activity as well. In addition, dietary exposure to 2,4-dichlorophenoxyacetic acid and to 2,4,5-trichlorophenoxyacetic acid resulted in increases in the activities of cytosolic and microsomal epoxide hydrolases in mouse liver and generally less pronounced increases in the total cytosolic glutathione transferase activity and microsomal content of cytochrome P-450. In the case of cytochrome P-450, this process can be said to be a true induction (i.e. the amount of enzyme protein is increased), because the assay procedure for cytochrome P-450 measures holoenzyme amount. Immunoquantitation demonstrated that this was also the case for the changes in cytosolic epoxide hydrolase. The dramatic differences in proliferation of peroxisomes and induction of xenobiotic-metabolizing enzymes seen here with compounds differing relatively little in structure may indicate that a receptor mechanism of some kind is involved.
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PMID:Induction of cytosolic and microsomal epoxide hydrolases and proliferation of peroxisomes and mitochondria in mouse liver after dietary exposure to p-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. 303 97

Exposure of rats to 1% or 3% (w/w) di(2-ethylhexyl)phosphate in the diet for five days results in two- to three-fold inductions of liver cytosolic epoxide hydrolase activity and microsomal cytochrome P-450 content. Cytochromes P-450b + e were induced 20- to 35-fold, but no increase was observed in cytochrome P-450c. Considerably smaller effects were obtained on NADPH-cytochrome c reductase, microsomal epoxide hydrolase and microsomal cytochrome b5 content, and there was no effect on cytosolic glutathione transferase activity, under the same conditions. A dramatic increase in cyanide-insensitive palmitoyl-CoA oxidation and total mitochondrial protein, together with smaller increases in total catalase and cytochrome oxidase activities, were observed after treatment with di(2-ethylhexyl)phosphate, indicating that this compound causes proliferation of both peroxisomes and mitochondria. It is suggested that the induction of cytosolic epoxide hydrolase and the proliferation of peroxisomes may be related processes.
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PMID:Induction of xenobiotic-metabolizing enzymes and peroxisome proliferation in rat liver caused by dietary exposure to di(2-ethylhexyl)phosphate. 311 Nov 7

The effects of sublethal heat pulses on cell division have provided insights into possible molecular mechanisms. Thus Zeuthen's findings of 'set-backs' up to a transition point provides the basis for the idea that the continuous accumulation of a compound needed for cell division spans a major portion of the cell cycle. The accumulating substance is a 'division protein' which forms part of a structure which is unstable until completely assembled at the transition point. Experiments showing phase resetting of mammalian cells by temperature perturbation indicate limit-cycle oscillator control of the cell cycle with a phase-response curve with a repeat interval equal to the period of the clock. As well as providing a method for establishing synchronized cultures these observations have found application in the selective effects of hyperthermia as an antitumour agent. Circadian rhythms display several unique features distinguishing them from other periodic processes. Only recently has it been recognized that some of these characteristics may be properties of ultradian rhythms as well. The probably most striking feature of circadian timekeeping, i.e. independence of ambient temperature, was found for ultradian rhythmicity even at the level of the unicellular organization. Synchronous cultures of some lower eukaryotes were prepared by centrifugal size selection methods. Experiments with asynchronous control cultures substantiated the view that the conditions employed were such as to minimize any perturbative effects: most importantly the organisms were never removed from their culture medium. Whereas the control cultures showed smoothly increasing respiration rates, total RNA, total protein, enzyme activities and enzyme protein (e.g. for cytochrome aa3, ATPase, catalase), in synchronous cultures all these parameters showed oscillatory behaviour. Different periods were observed in different organisms: thus in Acanthamoeba castellanii the period was about 70 min, in Tetrahymena pyriformis strain ST it was about 50 min, in T. pyriformis AII it was 30 min, and in Candida utilis it was about 30 min (all measurements at 30 degrees C). In A. castellanii the periods of both the oscillations in rate of respiration and the total cell protein were hardly affected by the temperature of growth over the range 20 to 30 degrees C. The oscillations show no damping during experiments lasting 12 h: these properties suggest that we are observing temperature-compensated endogenous rhythms which presumably serve a timekeeping function in cells undergoing growth and division.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:A temperature-compensated ultradian clock explains temperature-dependent quantal cell cycle times. 333 82

The effect of cyclosporin A treatment on rat hepatocytes was investigated using both short and prolonged exposure to the drug. During a 5-week period of high dose treatment. body weight, liver weight, protein content, and phospholipid content decreased somewhat, while the protein per phospholipid ratio in the isolated mitochondrial, microsomal, and peroxisomal fractions remained unchanged. Mitochondrial cytochrome oxidase activity increased considerably, and carnitine acetyl transferase decreased. The respiratory control ratio was completely intact and the level of oxidative phosphorylation was unchanged. The two microsomal electron transport chains exhibited inverse behavior: the NADH oxidizing system increased while the NADPH counterpart decreased. Contrary to the known peroxisomal inducers, cyclosporin A decreases beta oxidation of fatty acids in addition to catalase and urate oxidase activities in isolated peroxisomes which may suggest an inhibition of certain steps in protein synthesis. When rats were treated with lower doses of cyclosporin A over a 15-month period, we observed effects that were similar in several aspects to the ones obtained after the shorter period of exposure.
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PMID:Influence of cyclosporin A treatment on intracellular membranes of hepatocytes. 375 6


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