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)

A low-speed supernatant from dog liver was prepared and subjected to analytical subcellular fractionation using either preformed Percoll or reorientating sucrose density gradient centrifugation. In Percoll the following organelles, with marker enzymes and modal densities between brackets, were characterised: plasma membrane (alkaline phosphatase, 5' nucleotidase, gamma-glutamyl transferase, 1.039); endoplasmic reticulum (neutral alpha-glucosidase, 1.039); lysosomes (N-acetyl-beta-glucosaminidase, 1.087; alpha-mannosidase, 1.081) peroxisomes (catalase, 1.045) and mitochondria (succinate dehydrogenase, 1.081). In sucrose alkaline phosphatase had a bimodal particulate distribution (1.120, 1.187) distinct from that of 5' nucleotidase (1.160) and of gamma-glutamyl transferase (1.173). Other modal densities were: endoplasmic reticulum (1.187), lysosomes (1.227, 1.200), peroxisomes (1.213) and mitochondria (1.187). Further resolution was achieved by homogenisation in digitonin which disrupted lysosomes and, in sucrose, selectively increased the densities of the plasma membrane components. Both procedures therefore achieved distinct but quite different resolutions of organelles and should prove valuable for investigating subcellular pathology.
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PMID:Evaluation of preformed Percoll and reorientating sucrose density gradient centrifugation for the analytical subcellular fractionation of dog liver. 687 78

Experiments were carried out to determine if the difference in rates of cell proliferation between normal and neoplastic cells may be related to altered levels of oxidative enzymes. Assays were performed using homogenates from hepatocellular carcinoma HC-252, a rapidly growing and moderately well-differentiated tumor; from normal liver; and from the liver of the tumor-bearing ACI rat. Results of the mitochondrial enzymes indicated that the activities of cytochrome oxidase and succinate dehydrogenase were 3-fold lower in tumor homogenates than in liver homogenates. Monoamine oxidase activity could not be detected in HC-252; mixing experiments indicated no inhibitor was present in HC-252. Activities of th peroxisomal enzymes, urate oxidase, D-amino acid oxidase, and L-alpha-hydroxy acid oxidase were either undetected in the tumor or were 12-fold lower than in liver homogenates. The activity of xanthine oxidase, a cytoplasmic enzyme, was 5- to 6-fold lower in the tumor. Catalase activity in the tumor was also lower than in liver; this may be indicative of a lower oxidative environment at the cellular level. These enzyme activities of the liver of tumor-bearing rats were in the same range as those of normal rat liver, except that D-amino acid oxidase activity was slightly lower, and catalase activity was markedly lower and varied in a wide range. These results show an inverse correlation between the activities of oxygen-utilizing enzymes and rates of proliferation of one tumor line and its control. The possible implications of these results in neoplasia, cell proliferation, and cellular aging are discussed.
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PMID:Oxidoreductase activities in normal rat liver, tumor-bearing rat liver, and hepatoma HC-252. 689 80

The subcellular distribution and nature of rat renal renin has been investigated by means of analytical subcellular fractionation and gel filtration on Sephadex G-100. During differential centrifugation, renin activity was recovered mainly in soluble and heavy mitochondrial fractions. On sucrose gradient centrifugation in either a conventional or in a B XIV zonal rotor, renin activity equilibrated at 1.54 M sucrose and was partially resolved from marker enzymes for mitochondria (succinate dehydrogenase), lysosomes (acid phosphatase), plasma membranes (alkaline phosphatase), and peroxisomes (catalase). On gel filtration of the soluble or extracts of the renin-granular fractions on Sephadex G-100, renin activity eluted as a single peak with an apparent molecular weight (MW) of 42,000; no change in activity was found when these fractions were acidified to pH 3.0. When kidney homogenates were prepared in the presence of the proteolytic inhibitor N-ethylmaleimide (NEM, 10 mM), whereas the renin from the granular fractions displayed a MW of 44,000, that from the soluble fraction was apparently higher (69,000). Addition of NEM (10 mM) to the soluble fraction previously shown to contain only the low MW form of renin also resulted in an apparently high MW form of renin. These results indicate that rat renal renin is associated with a mechanically fragile, distinct type of subcellular organelle. Renin within this structure is of the low MW form and is not acid activatable. The soluble fraction, however, contains a factor(s) that, in the presence of NEM, combines with the low MW renin to form a complex of apparently high MW.
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PMID:Subcellular distribution and storage form of rat renal renin. 699 67

The energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or sucrose. Furthermore, support comes from the fact that enzymes generally associated with the Krebs cycle and electron transport (i.e., malate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, fumarate hydratase, malate dehydrogenase [decarboxylating], cytochrome oxidase, superoxide dismutase, NADH dehydrogenase, and catalase) were detected. Those enzymes normally associated with glycolysis and the hexose monophosphate pathways (i.e., hexokinase, glucose 6-phosphate dehydrogenase, fructose biphosphate aldolase, glycerol 3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, pyruvate kinase, phosphate acetyl transferase, acetate kinase, alcohol dehydrogenase, and lactate dehydrogenase) were below the level of detection.
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PMID:Energy metabolism of the contagious equine metritis bacterium. 708 71

EPR spectroscopy was used to investigate the cytochrome P-450-dependent steroid hydroxylase ecdysone 20-mono-oxygenase of the cotton leafworm (Spodoptera littoralis) and the redox centres associated with membranes from the fat-body mitochondrial fraction. Intense features at g = 2.42, 2.25 and 1.92 from oxidized mitochondrial membranes have been assigned to the low-spin haem form of ferricytochrome P-450, probably of ecdysone 20-mono-oxygenase. High-spin cytochrome P-450 (substrate-bound) was tentatively assigned to a signal at g = 8.0, which was detectable from membranes as prepared. An EPR signal characteristic of a [2Fe-2S] cluster detected from the soluble mitochondrial matrix fraction has been shown to be distinct from the signals associated with mitochondrial NADH dehydrogenase and succinate dehydrogenase, and has therefore been attributed to a ferredoxin. We conclude that the S. littoralis fat-body mitochondrial electron-transport system involved in steroid 20-hydroxylation comprises both ferredoxin and cytochrome P-450 components, and thus resembles the enzyme systems of adrenocortical mitochondria. EPR signals characteristic of the respiratory chain were also observed from fat-body mitochondria and assigned to the iron-sulphur clusters associated with Complex I (Centres N1, N2), Complex II (Centres S1, S3), Complex III (the Rieske centre), and the copper centre of Complex IV, demonstrating similarities to mammalian mitochondria. The reduced membrane fraction also yielded a major resonance at g = 2.09 and 1.88 characteristic of the [4Fe-4S] cluster of electron-transferring flavoprotein: ubiquinone oxidoreductase. As the fat-body is the major metabolic organ of insects, this protein is presumably required for the beta-oxidation of fatty acids in mitochondria. High-spin haem signals in the low-field region of spectra also demonstrated that the mitochondrial fraction contains relatively high concentrations of catalase.
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PMID:EPR spectroscopic characterization of the iron-sulphur proteins and cytochrome P-450 in mitochondria from the insect Spodoptera littoralis (cotton leafworm). 774 2

Parkinson's disease (PD) is characterized mainly by a loss of nigrostriatal dopamine neurons. Thus far, the actual physiopathology of PD remains uncertain, although recent studies have found decreased activity of complex I, one of the enzymatic units of the mitochondrial respiratory chain, in various tissues of PD patients. Because most, if not all, of PD patients are treated chronically with levodopa, the precursor of dopamine, and because we have shown previously that catecholamines may alter mitochondrial respiration, we assessed the effects of chronic administration of levodopa on complex I activity in rat brain. We found that chronic administration of levodopa, at a dose used in PD patients, caused a significant reduction in complex I activity while it did not affect the activities of complex II, complex IV, and citrate synthase. Reduction in complex I activity correlated well with catecholamine innervation as the reduction was observed mainly in the striatum and substantia nigra and to a lesser extent in the frontal cortex but not in the cerebellum. Moreover, the levodopa-induced decrease of complex I activity was reversible since activities at 1, 3, and 7 days after the last injection showed a progressive return to control values. Incubation of whole brain mitochondria in vitro showed that both levodopa and dopamine inhibit complex I activity in a dose- and time-dependent manner. In contrast, other compounds such as homovanillic acid, 3,4-dihydroxyphenylacetic acid, and 3-O-methyl-dopa were minimally effective. Reduced glutathione, ascorbate, superoxide dismutase, and catalase prevented the effect of levodopa and dopamine on complex I. Various inhibitors of monoamine oxidase also prevented the effect of dopamine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Chronic levodopa administration alters cerebral mitochondrial respiratory chain activity. 823 66

Human blood mononuclear cells exposed to visible light increase their antioxidant enzyme (superoxide dismutase, catalase, and glutathione peroxidase) and DT-diaphorase activities. The activities of CuZn-superoxide dismutase (3.70 +/- 0.25 U/mg protein), catalase (4.60 +/- 0.39 U/mg protein), and DT-diaphorase (1.40 +/- 0.11 mumol DCPIP/min.mg protein) increased 1.5-fold when mononuclear cells were exposed at 38 W/m2 for 4 h. Se-containing glutathione peroxidase activity (6.76 +/- 0.21 mU/mg protein) increased 1.3 times after 3 h of exposure to 38 W/m2. Conversely, Mn-superoxide dismutase (2.20 +/- 0.20 U/mg protein), succinate dehydrogenase (0.86 +/- 0.04 mumol DCPIP/min.mg protein), and cytochrome oxidase (0.54 +/- 0.04 min-1 (k')/mg protein) activities remained constant during this period of exposure. The treatment of cells with cycloheximide prevented the response triggered by light exposure. These results introduce new insight to the adaptive response of human cells to light stress suggesting that: (a) the response observed might be ascribed to synthesis of stress proteins rather than to activation of a preexisting pool, and (b) that DT-diaphorase and CuZn-superoxide dismutase may operate biologically in a concerted fashion resulting in antioxidant activity.
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PMID:Induction of antioxidant enzymes and DT-diaphorase in human blood mononuclear cells by light stress. 837 61

1. Electron paramagnetic resonance spectroscopy was used to study free-radical signals in freeze-clamped frozen liver tissue from rats after a 1 year period of dietary supplementation with alcohol, iron, or alcohol and iron. In alcohol-fed, iron-fed and alcohol- and iron-fed animals, mild histological damage was seen on light microscopy and evidence of mitochondrial and nuclear injury was identified by electron microscopy. 2. Subcellular fractionation studies showed an increase in the activity of the peroxisomal marker catalase (P < 0.01) in alcohol-fed rats compared with controls, but a fall of 82% (P < 0.001) in alcohol- and iron-fed animals. The activity of the mitochondrial marker succinate dehydrogenase rose by 7% (not significant) in alcohol-fed animals and by 17% (not significant) in iron-fed animals, but fell by 94% (P < 0.001) in alcohol- and iron-fed animals, suggesting serious impairment of mitochondrial function. 3. Iron overload was substantial in the iron-fed animals and there was an excellent correlation between liver iron concentration and iron-derived signals by electron paramagnetic resonance spectroscopy (P < 0.001). A clear free-radical signal of g = 2.003-2.005 was detected in all liver samples, but there was no significant difference in the magnitude of this signal in any study group. 4. The absence of any increase in the stable free-radical signal, even in the presence of considerable hepatic damage, does not support the hypothesis that free radicals mediate alcoholic liver disease in this animal model, although the results cannot be taken as proof against this hypothesis.
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PMID:Electron paramagnetic resonance spectroscopy of stable free radicals in the liver compared with ultrastructural and functional damage in a rat model of alcohol- and iron-overload. 838 57

The effect of storage of unfixed cryostat sections from rat liver for 4 h, 24 h, 3 days and 7 days at -25 degrees C was studied on the activities of lactate dehydrogenase, glucose-6-phosphate dehydrogenase, xanthine oxidoreductase, glutamate dehydrogenase, succinate dehydrogenase (all demonstrated with tetrazolium salt procedures), glucose-6-phosphatase (cerium-diaminobenzidine method), 5'-nucleotidase (lead salt method), dipeptidyl peptidase II, acid phosphatase (both simultaneous azo coupling methods), D-amino acid oxidase (cerium-diaminobenzidine-cobalt-hydrogen peroxide procedure) and catalase (diaminobenzidine method). The effect of drying of the cryostat sections at room temperature for 5 and 60 min was investigated as well. The enzyme activities were quantified by cytophotometric measurements of test and control reactions. The test minus control reaction was taken as a measure for specific enzyme activity. It was found that the activities of all the enzymes investigated, with one exception, were affected neither by storage of the cryostat sections at -25 degrees C for up to 7 days, nor by drying of the sections at room temperature for up to 60 min. The exception was xanthine oxidoreductase, whose activity was reduced by 20% after 5 min drying of sections or after 4 h storage. Therefore, only incubations for xanthine oxidoreductase activity have to be performed immediately after cutting cryostat sections, whereas for the other enzymes a considerable margin appears to exist.
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PMID:The effects of storage on the retention of enzyme activity in cryostat sections. A quantitative histochemical study on rat liver. 846 85

Human (HepG2) and rat (MH1C1) hepatoblastoma cells were incubated with different concentrations of the hypolipidaemics cetaben, clofibrate and thyroxine. The enzymatic activities of catalase, peroxisomal bifunctional enzyme, succinate dehydrogenase, and 3-oxoacyl-CoA thiolase were measured. In order to determine the point of regulation of the enzymatic activities Northern and Slot blot experiments with probes for peroxisomal bifunctional enzyme, catalase and fatty acyl CoA oxidase were performed on total RNA. Catalase activity was enhanced in HepG2 cells treated with 3 mmol/l clofibric acid to 135% of control and the mRNA value to 2.6 fold, whereas in cetaben treated cells the enhancement (up to 119% of control) was less pronounced. In MH1C1 cells catalase activity was not changed by any of the drugs. The activity of the peroxisomal bifunctional enzyme was not affected in HepG2 cells by clofibric acid and cetaben, whereas the mRNA level was elevated to 2.3 fold by 10 micromol/l cetaben. At high concentrations of cetaben all enzyme activities were decreased in both cell lines due to its high cytotoxicity. Our data show that, due to the differences in the genomic organisation, the regulation of the enzyme activities is different in human and rat, but the results from the human and rat hepatoblastoma cells correlate with the findings in whole man and rat, so that a human in vitro system is more suitable for pharmacological tests. These results suggest that the human hepatoma cell line HepG2 may be a useful model system for studies of the influence of hypolipidaemics on the peroxisomal enzyme system.
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PMID:Differential induction of peroxisomal enzymes by hypolipidaemics in human (HepG2) and rat (MH1C1) hepatoma cell lines. 862 53


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