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)

To determine the effect of long-term thyrotoxicosis on muscle mitochondria, we measured representative mitochondrial enzymes from three different types of skeletal muscle (fast-twitch red and fast-twitch white from the quadriceps, and slow-twitch red from the soleus) in rats given 3 mg L-thyroxine and 1 mg triiodo-L-thyronine per kilogram of diet for 12 wk. Marker enzymes of the electron transport chain and citric acid cycle (cytochrome oxidase, cytochrome c, and citrate synthase) increase approximately twofold in soleus muscle in response to this treatment. The fast-twitch muscles exhibit no more than 44% increases in these enzymes in response to the same treatment. Relative to initial concentration, 3-hydroxybutyrate dehydrogenase increased to the same extent in fast-twitch red muscle as it did in the soleus (70%). Mitochondrial alpha-glycerophosphate dehydrogenase increased 76% in red quadriceps and 170% in soleus, but did not change in white muscle in the thyrotoxic rats. This differential sensitivity of the three types of muscle provides a tool for studying the mechanisms underlying the action of thyroid hormones on muscle mitochondria.
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PMID:Response of mitochondria of different types of skeletal muscle to thyrotoxicosis. 19 5

Subcellular localization of enzymes of arginine metabolism in Saccharomyces cerevisiae was studied by partial fractionation and stepwise homogenization of spheroplast lysates. These enzymes could clearly be divided into two groups. The first group comprised the five enzymes of the acetylated compound cycle, i.e., acetylglutamate synthase, acetylglutamate kinase, acetylglutamyl-phosphate reductase, acetylornithine aminotransferase, and acetylornithine-glutamate acetyltransferase. These enzymes were exclusively particulate. Comparison with citrate synthase and cytochrome oxidase, and results from isopycnic gradient analysis, suggested that these enzymes were associated with the mitochondria. By contrast, enzymatic activities going from ornithine to arginine, i.e., arginine pathway-specific carbamoylphosphate synthetase, ornithine carbamoyltransferase, argininosuccinate synthetase, and argininosuccinate lyase, and the two first catabolic enzymes, arginase and ornithine aminotransferase, were in the "soluble" fraction of the cell.
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PMID:Arginine metabolism in Saccharomyces cerevisiae: subcellular localization of the enzymes. 20 32

The changes induced by phenobarbital in cerebral enzymatic activities of the Krebs' cycle (citrate synthase, malate dehydrogenase) and electron transfer chain (total NADH-cytochrome c reductase and cytochrome oxidase) were studied. In addition, the activity of lactate dehydrogenase of acetylcholine esterase and of glutamate dehydrogenase was also studied. These enzymatic activities were evaluated in the homogenate in toto and in a crude mitochondrial fraction from rat brain. The modifications in some of these activities indicate that several new metabolic situations occur in brain tissue after phenobarbital treatment.
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PMID:Effect of phenobarbital on cerebral energy state and metabolism. Enzymatic activities. 23 Jun 18

The effects of L-carnitine on respiratory chain enzymes in muscle of long distance runners were studied in 14 athletes. These subjects received placebo or L-carnitine (2 g orally b.i.d.) during a 4-week period of training. Athletes receiving L-carnitine showed a significant increase (p < 0.01) in the activities of rotenone-sensitive NADH cytochrome c reductase, succinate cytochrome c reductase and cytochrome oxidase. In contrast, succinate dehydrogenase and citrate synthase were unchanged. No significant changes were observed after placebo administration. The levels of both total and free carnitine from athletes receiving placebo were significantly decreased (p < 0.01) after treatment. By contrast, total and free carnitine levels were markedly increased (p < 0.01) after supplementation with L-carnitine. Our results suggest that L-carnitine induces an increase of the respiratory chain enzyme activities in muscle, probably by mechanisms involving mitochondrial DNA.
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PMID:Respiratory chain enzymes in muscle of endurance athletes: effect of L-carnitine. 132 42

The effect of chronic left ventricular pressure overload on the activities of mitochondrial respiratory chain enzymes was investigated in myocardial biopsies from the left ventricular apex of 13 patients undergoing aortic valve replacement for aortic valve stenosis. Transvalvular pressure gradients measured by left-sided heart catheterization ranged from 52 to 100 mmHg. The specific activity of mitochondrial respiratory chain enzyme complexes I+III (antimycin A sensitive NADH cytochrome c oxidoreductase) and the myocardial concentrations of coenzyme Q10 (CoQ10) increased significantly (P < 0.05) with increasing aortic valve pressure gradient. In contrast, the specific activities of complex IV (cytochrome c oxidase), succinate dehydrogenase, and citrate synthase, a mitochondrial matrix enzyme, showed no significant correlation with the pressure gradient. Since CoQ10 is the rate-limiting compound of the activity of complexes I+III but not of cytochrome c oxidase, succinate dehydrogenase, or citrate synthase, these data suggest that the increase in the activity of complexes I+III is due to the increase in CoQ10 content.
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PMID:Positive correlation between aortic valve pressure gradient and mitochondrial respiratory chain capacity in hypertrophied human left ventricle. 145 Jun 14

The maximal rates (Vmax) of some mitochondrial enzyme activities related to energy transduction (citrate synthase, succinate dehydrogenase, malate dehydrogenase, NADH-cytochrome c reductase, cytochrome oxidase) and amino acid metabolism (glutamate dehydrogenase, glutamate-pyruvate- and glutamate-oxaloacetate- transaminases) were evaluated in non-synaptic ("free") and intrasynaptic "light" and "heavy" mitochondria from hippocampus of Macaca fascicularis (Cynomolgus monkey). The different mitochondrial populations were isolated from the hippocampus of monkeys treated p.o. with dihydroergocryptine at a dose of 12 mg/kg/day before and during the induction of a Parkinson's-like syndrome by MPTP administration (i.v., 0.3 mg/kg/day for 5 days). The MPTP administration modified the activity of some enzymes related to the metabolism of glutamate and the activity of succinate dehydrogenase on selected types of mitochondria. Pharmacological treatment by dihydroergocryptine promoted return to the steady-state levels of most enzymes, demonstrating a protective effect on these biochemical parameters.
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PMID:Mitochondrial factors involved in Parkinson's disease by MPTP toxicity in Macaca fascicularis and drug effect. 146 62

The adaptation of mitochondrial ATP production rate (MAPR) to training and detraining was evaluated in nine healthy men. Muscle samples (approximately 60 mg) were obtained before and after 6 wk of endurance training and after 3 wk of detraining. MAPR was measured in isolated mitochondria by a bioluminometric method. In addition, the activities of mitochondrial and glycolytic enzymes were determined in skeletal muscle. In response to training, MAPR increased by 70%, with a substrate combination of pyruvate + palmitoyl-L-carnitine + alpha-ketoglutarate + malate, by 50% with only pyruvate + malate, and by 92% with palmitoyl-L-carnitine + malate. With detraining MAPR decreased by 12-28% from the posttraining rate (although not significantly for all substrates). No differences were found when MAPR was related to the protein content in the mitochondrial fraction. The largest increase in mitochondrial enzyme activities induced by training was observed for cytochrome-c oxidase (78%), whereas succinate cytochrome c reductase showed only an 18% increase. The activity of citrate synthase increased by 40% and of glutamate dehydrogenase by 45%. Corresponding changes in maximal O2 uptake were a 9.6% increase by training and a 6.0% reversion after detraining. In conclusion, both MAPR and mitochondrial enzyme activities are shown to increase with endurance training and to decrease with detraining.
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PMID:Adaptation of mitochondrial ATP production in human skeletal muscle to endurance training and detraining. 147 78

The influence of tapering on the metabolic and performance parameters in endurance cyclists was investigated. Cyclists (n = 25) trained 5 days.week-1, 60 min.day-1, at 75-85% maximal oxygen consumption (VO2max) for 8 weeks and were then randomly assigned to a taper group: 4D (4 days; n = 7), 8D (8 days; n = 6), CON (control, 4 days rest; n = 6), NOTAPER (non-taper, continued training; n = 6). Muscle biopsy specimens taken before and after training and tapering were analysed for carnitine palmityltransferase (CPT), citrate synthase, beta-hydroxyacyl CoA dehydrogenase (HOAD), cytochrome oxidase (CYTOX), lactate dehydrogenase, glycogen and protein. Significant increases in VO2max (6%), a 60-min endurance cycle test (34.5%), oxidative enzymes (77-178%), glycogen (35%) and protein (34%) occurred following training. After the taper, HOAD and CPT decreased 25% (P less than 0.05) and 26% respectively, in the CON. Post-taper CYTOX values were different (P less than 0.05) for 4D and 8D compared with CON. Muscle glycogen levels were increased (P less than 0.05) after tapering in the 4D, 8D and CON, but decreased in NOTAPER. Similarly, power output at ventilation threshold was significantly increased in the 4D (27.4 W) and 8D (27 W) groups, but decreased (22 W) in the NOTAPER. These findings suggest that tapering elicited a physiological adaptation by altering oxidative enzymes and muscle glycogen levels. Such an adaptation may influence endurance cycling during a laboratory performance test.
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PMID:The effects of a reduced exercise duration taper programme on performance and muscle enzymes of endurance cyclists. 150 37

The activities of enzymes related to energy metabolism in the gastrocnemius and soleus muscles in young-adult (4 months), mature (12 months), and senescent (24 months) rats were compared after continuous (72 consecutive h) exposure to normobaric hypoxia or normoxia after the vasodilator naftidrofuryl or saline solution had been given intraperitoneally for 30 consecutive days. The maximum rats (Vmax) of the following enzyme activities in the crude extract and/or the crude mitochondrial fraction of each muscle specimen were evaluated for: the anaerobic glycolytic pathway (hexokinase, phosphofructokinase, pyruvate kinase, and lactate dehydrogenase), the tricarboxylic acid cycle (citrate synthase, and malate dehydrogenase), the electron transfer chain (cytochrome oxidase), and the NAD+/NADH redox state (total NADH cytochrome c reductase). The significance of differences between the enzyme activities at different ages or under different experimental conditions in the two tissue preparations of the two muscles were determined by ANOVA. MCA and ETA2 were used to evaluate the net effects of the experimental conditions. First, aging did not seem to affect the soleus and gastrocnemius muscles in the same way. In the gastrocnemius muscle, the major changes were seen in enzymes of the glycolytic pathway, in the crude extracts. In the soleus muscle, the more striking changes in enzyme activities as a function of aging were found in the crude mitochondrial fraction. We also found that hypoxia caused more important changes in 12-month-old rats than in those of other ages (especially the enzyme activities of the gastrocnemius muscle). Naftidrofuryl modified the effects of hypoxia only sometimes and further investigations are necessary before we can draw any conclusions about the pharmacological activity of naftidrofuryl in hypoxia.
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PMID:Effects of hypoxia and pharmacological treatment on enzyme activities in skeletal muscle of rats of different ages. 164 27

Cardiac hypertrophy was produced in embryonic chicks by decreasing the incubation temperature from 38 degrees C to 32 degrees C on day 11. Increases in ventricular protein, RNA, and DNA support the cardiac enlargement. Cytochrome-c oxidase activity and citrate synthase activity were depressed in hypothermic ventricles by 63% and 56%, respectively. No significant differences were seen in enzyme activities in pectoralis muscles. The involvement of mitochondrial gene replication and transcription was evaluated using a cDNA clone for the mitochondrially encoded subunit III of cytochrome-c oxidase (CO III). Quantitative slot-blot analysis demonstrated that the relative CO III mRNA concentration was reduced in hypothermic ventricles. In contrast, the relative mitochondrial DNA concentration was increased in hypothermic ventricles. Taken together, these data indicate that a hypothermia-induced decrease in cytochrome-c oxidase activity is associated with a decrease in CO III mRNA, which is not coupled to a decrease in the mitochondrial DNA copy number. This dissociation of mitochondrial gene replication and transcription may provide a useful model for examining the regulation of mitochondrial biogenesis.
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PMID:Mitochondrial DNA replication and transcription are dissociated during embryonic cardiac hypertrophy. 166 4


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