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:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The photosensitizing activity of hematoporphyrin derivative (HPD) was investigated by studying selected enzymes localized to mitochondria and cytosol of R3230AC mammary adenocarcinomas. Experiments in vitro demonstrated that mitochondrial succinate dehydrogenase was inhibited in a drug dose- and light exposure time-related manner; at 7.0 micrograms of HPD per ml or higher, enzyme activity was inhibited greater than 50% after 15 min of photoradiation. The three cytosol enzymes studied under the same conditions in vitro demonstrated different photosensitivities. Pyruvate kinase activity was significantly inhibited in a dose- and time-related fashion, whereas lactate dehydrogenase was inhibited to a lesser extent, and glucose phosphate isomerase activity was inhibited only at the highest dose (70 micrograms of HPD per ml) used. The time-course of these responses was examined with an in vivo-in vitro protocol, consisting of photoradiation of mitochondria and cytosol prepared from tumors obtained at various times (up to 1 week) after a single injection of HPD (80 mg/kg). Pyruvate kinase activity was markedly inhibited at early times returning to initial levels by 48 hr; neither lactate dehydrogenase nor glucose phosphate isomerase was inhibited by this treatment. Mitochondrial succinate dehydrogenase and cytochrome c oxidase activities displayed significant photoradiation-induced inhibitions, with greatest inhibition occurring between 24 and 96 hr after injection of HPD; at 1 week, succinate dehydrogenase activity had returned to its initial level, but cytochrome c oxidase activity remained significantly inhibited. These data suggest that HPD-induced photosensitization of mitochondria may be an important site of action contributing to tumor cell cytotoxicity and regression as a result of photoradiation therapy.
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PMID:Hematoporphyrin derivative-induced photosensitivity of mitochondrial succinate dehydrogenase and selected cytosolic enzymes of R3230AC mammary adenocarcinomas of rats. 623 Oct 99

We studied the effects of running-training, heavy exercise and termination of training on the heart weight, the ratio heart to body weight and the cardiac muscle activities of actomyosin ATPase, citrate synthase, succinate dehydrogenase, cytochrome c oxidase, malate dehydrogenase, adenylate kinase and beta-glucuronidase with adult male NMRI-mice. Stable hypertrophy (6-7%), estimated by the ratio heart or ventricle weight to body weight, was achieved by 28 exercises and it was dependent on the running speed (20 vs. 25 m X min-1). The withdrawal of training for 5-61 days did not permanently decrease the heart weight or the heart to body weight ratio to the level of sedentary controls. The activity of enzymes of energy metabolism or actomyosin ATPase were not affected by training, heavy exercise or terminated training. beta-glucuronidase activity slightly (20-25%) increased in the trained animals and remained at a higher level during the period of terminated training. The results suggest that the capacity for aerobic metabolism of normal mice heart is sufficient to meet the enhanced demand for ATP imposed by running-training and that the heart enlargement occurs in equal proportions with the enzymatic potential of the cardiac tissue.
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PMID:Selected enzyme activities in mouse cardiac muscle during training and terminated training. 623 64

The photosensitivity of freshly dissociated R3230AC mammary adenocarcinoma cells was examined by measurement of the activities of selected intracellular enzymes after treatment with hematoporphyrin derivative (Hpd) and exposure to light in vitro. Enzymes selected as representative of the cytosolic cell compartment showed no loss in activity, whereas malate dehydrogenase, located in the mitochondrial matrix, displayed a modest decrease (approximately 15%) in activity. In contrast, cytochrome c oxidase and succinate dehydrogenase, enzymes associated with the mitochondrial membrane, demonstrated a very rapid and more marked inhibition of activities, approximately 45% and 25%, respectively. The time-course of inhibition of these mitochondrial membrane enzymes preceded the loss of cell viability, which displayed slower kinetics as seen by a more gradual and progressive pattern of loss in viability. These data suggest that the mitochondria are an early-affected and important intracellular site for Hpd photosensitization.
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PMID:Photodynamic inactivation of selected intracellular enzymes by hematoporphyrin derivative and their relationship to tumor cell viability in vitro. 623 75

One of us has previously reported that treatment of the Keilin and Hartree heart-muscle preparation with 2,3-dimercaptopropanol (BAL), in the presence of air, leads to the complete inactivation of the succinate oxidase system with little if any effect on the activities of succinate dehydrogenase (until more than half the BAL was oxidized) or cytochrome c oxidase. The inactivation of the complete succinate oxidase system requires the oxidation of BAL by air in the presence of the enzyme. It is not caused by H2O2 or BAL disulphides produced during the oxidation of BAL. Spectroscopic studies identified the block as lying between cytochromes b and c. It was suggested that a BAL-labile factor is present which transfers electrons from cytochrome b to cytochrome c and which is destroyed by coupled oxidation with BAL. The factor is also required for NADH oxidation. Subsequent work showed it is not identical with cytochrome c1 (ref. 4), myoglobin present in the preparation or the antimycin-binding site. We report here that this factor is identical to the iron-sulphur protein in the central portion of the respiratory chain first identified by Rieske.
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PMID:Identification of the BAL-labile factor. 625 40

Local anesthetics and alcohols were found to inhibit mitochondrial electron transport at several points along the chain. THe anesthetics employed were the tertiary amines procaine, tetracaine, dibucaine, and chlorpromazine, and the alcohols were n-butamol, n-pentanol, n-hexanol, and benzyl alcohol. Uncoupled sonic submitochondrial particles from beef heart and rat liver were studied. We report the following: (1) All of the anesthetics were found to inhibit each of the segments of the electron transport chain assayed; these included cytochrome c oxidase, durohydroquinone oxidase, succinate oxidase, NADH oxidase, succinate dehydrogenase, succinate-cytochrome c oxidoreductase, and NADH-cytochrome c oxidoreductase. (2) NADH oxidase and NADH-cytochrome c oxidoreductase required the lowest concentration of anesthetic for inhibition, and cytochrome c oxidase required the highest concentrations. (3) We conclude that there are several points along the chain at which inhibition occurs, the most sensitive being in the region of Complex I (NADH dehydrogenase). (4) Beef heart submitochondrial particles are less sensitive to inhibition than are rat liver particles. (5) Low concentrations of several of the anesthetics gave enhancement of electron transport activity, whereas higher concentrations of the same agents caused inhibition. (6) The concentrations of anesthetics (alcohol and tertiary amine) which gave 50% inhibition of NADH oxidase were lower than the reported concentrations required for blockage of frog sciatic nerve.
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PMID:Multiple sites of inhibition of mitochondrial electron transport by local anesthetics. 626 99

Ischemic myocardium was produced by occluding the left circumflex coronary artery in anesthetized dogs. Autolyzed myocardium was produced by incubating transmural samples of canine left ventricle at 37 degrees C. Tissue pH was recorded continuously in each model using a microcombination pH electrode impaled into the midmyocardium. The activities of the five mitochondrial inner membrane enzyme complexes of electron transport and coupled oxidative phosphorylation were assayed as a function of time of ischemia or autolysis. While the activities of complex II (succinate-CoQ reductase) and IV (cytochrome c oxidase) were completely stable, that of complex I (NADH-CoQ reductase) decreased markedly, but largely only after 20 min of ischemia or autolysis. At 20 min and beyond, the decrease in the activity of complex I paralleled closely the decrease in whole mitochondrial oxygen uptake with NAD-linked substrates in both models. The activity of complex III (CoQH2-c reductase) decreased at a more gradual rate during ischemia or autolysis, and its rate of decrease paralleled that of succinate-supported oxygen uptake. The activity of complex V (oligomycin-sensitive ATPase) decreased most rapidly (by 40% in only 5 min of autolysis) but nearly leveled off beyond 20 min in the two models. A strikingly similar pattern of differential enzyme lability was observed in isolated control mitochondria incubated at lowered pH values. The results demonstrate 1) differential enzyme lability within the mitochondrial inner membrane, 2) a connection between severity of acidosis and the degree of enzyme activity loss, and 3) the usefulness of simple tissue autolysis as an analogue of in situ myocardial ischemia.
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PMID:Mitochondrial complexes I, II, III, IV, and V in myocardial ischemia and autolysis. 630 12

The effect of endurance training on skeletal muscle myoglobin concentration in man was investigated. 8 healthy sedentary males (20-31 yrs) trained on cycle ergometers 40 min/day, 4 days a week for 8 weeks. The work consisted of continuous exercise at a work load that during the last 5 weeks corresponded to 75% of the pretraining maximal oxygen uptake (VO2 max). The training program resulted in a 7% increase in VO2 max (p less than 0.01). The activities of the mitochondrial enzymes citrate synthase (CS), succinate dehydrogenase (SDH) and cytochrome c oxidase (Cyt-c-ox) in the quadriceps femoris muscle, as indicators of muscle respiratory capacity, increased by 62-82% (p less than 0.01). The metabolic adaptation of skeletal muscle was further indicated by a 17% increase in the work load corresponding to a blood lactate concentration of 4 mmol/l, as determined by a progressive exercise test (p less than 0.05). There was, however, no change in the myoglobin concentration of the thigh muscle with training (-1%, NS). It is suggested that endurance exercise in man at 75% of the maximal oxygen uptake does not severely tax the functions of myoglobin in skeletal muscle.
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PMID:Dissociation of training effects on skeletal muscle mitochondrial enzymes and myoglobin in man. 630 98

The inhibitory effect of econazole nitrate on the growth of yeast Saccharomyces cerevisiae is proportional to the concentration of the product. It depends on the phase of culture and on the number of cells present at the moment of econazole addition into the medium. The most important inhibition is obtained in the exponential phase of growth with a low concentration of cells. It is enhanced with cells which were previously in contact with the product. There is no adaptation of the yeast toward increased concentrations of econazole. The product penetrates the cells and attaches first to particular fractions, later to soluble fractions. The highest concentration of econazole nitrate in cells lies in the mitochondria. No product of econazole metabolism by S. cerevisiae was uncovered. Econazole nitrate does not slow down the in vivo activities of mitochondrial enzymes (cytochrome c oxidase, succinate dehydrogenase and phenylalanyl-tRNA synthetase), but inhibits the biosynthesis of mitochondrial membrane enzymes without affecting that of the synthetase, a matrix enzyme.
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PMID:Effects of econazole nitrate on yeast cells and mitochondria. 634 41

The effects of selenium on 7,12-dimethylbenzanthracene-induced mammary tumorigenesis were examined in C57BL X DBA/2f F1 mice fed a semipurified diet. Mice fed 0.2 ppm selenium developed 56% mammary tumors; in contrast, mice fed 2.0 ppm selenium developed only 16% mammary tumors at 11 months of age. Mice fed the 2.0-ppm selenium diet grew as well as did their counterparts fed the 0.2-ppm selenium diet. In a separate experiment, the level of selenium-dependent glutathione peroxidase was measured in the mammary glands of control and 7,12-dimethylbenzanthracene-treated BALB/c mice fed basal and selenium-supplemented diets. 7,12-Dimethylbenzanthracene treatment resulted in decreased glutathione peroxidase activity n mice fed both low (0.03 ppm)- and high (1.50 ppm)-selenium diets. Thus, the chemopreventive effects of selenium could not be attributed to maintaining high levels of glutathione peroxidase. In a second series of experiments, the effects of selenium were further examined on the growth of mammary cell line YN-4 in monolayer cell culture. The mitochondrial inclusions seen in cells exposed to 5 X 10(-6) M selenium could not be correlated with changes in the activity of the mitochondrial enzymes, cytochrome c oxidase and succinate dehydrogenase, thus implying that there was no demonstratable impairment of mitochondria. The examination of selenium-treated cells with flow cytofluorometry indicated that cells were blocked in S-G2 phases of the cell cycle. This latter result illustrates one feasible approach towards identifying specific mechanisms for the chemopreventive effects of selenium.
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PMID:Selenium and mouse mammary tumorigenesis: an investigation of possible mechanisms. 640 37

In autopsied brain tissue from three cases with Leigh disease (subacute necrotizing encephalomyelitis, SNE) and controls, the activity of pyruvate dehydrogenase complex (PDHC) was determined under different conditions. It was found to be at the control level or increased, but not deficient. The activities of succinate dehydrogenase, fumarase, succinate cytochrome c reductase, cytochrome c oxidase, and glutamate dehydrogenase were measured as additional mitochondrial markers and showed no essential differences between SNE and control tissue. The metabolic defect in SNE remains unknown. According to the literature, the defect may be localized to the mitochondrial systems. However, the reported results indicate that it cannot be ascribed to PDHC function. Extensive biochemical studies are necessary for understanding of the pathogenesis in the fatal genetic metabolic disease.
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PMID:Pyruvate dehydrogenase activity is not deficient in the brain of three autopsied cases with Leigh disease (subacute necrotizing encephalomyelopathy, SNE). 643 63


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