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)

1. A polarographic assay of superoxide (O2--) dismutase (EC 1.15.1.1) activity is described, in which the ability of the enzyme to inhibit O2---dependent sulphite oxidation, initiated by xanthine oxidase activity, is measured. The assay was used in a study of the intracellular distribution of superoxide dismutase in rat liver. Both cyanide-sensitive cupro-zinc dismutase (92% of the total activity) and cyanide-insensitive mangano-dismutase (8%) were measured. 2. Rat liver homogenates contained both particulate (16%y and soluble (84%) dismutase activity. The particulate activity contained both types of dismutase, whereas nearly all the soluble dismutase was a cupro-zinc enzymes. The distribution pattern of mangano-dismutase was similar to that of cytochrome oxidase and glutamate dehydrogenase, indicating that the enzyme was probably present exclusively in the mitochondria. 3. Superoxide dismutase activity in the heavy-mitochondrial (M) fraction was latent and was activated severalfold and largely solubilized by sonication. Treatment of the M fraction with digitonin or a hypo-osmotic suspending medium indicated that most of the cupro-zinc dismutase was located in the mitochondrial intermembrane space, whereas the mangano-enzyme was located in the inner-membrane and matrix space. 4. A small amount of dismutase activity appeared to be present in the nuclei and microsomal fraction, but little or no activity in the lysosomes or peroxisomes. 5. The results are discussed in relation to the intracellular location of known O2---generating enzymes, the possible role of superoxide dismutase activity in intracellular H2O2 formation, and to current views on the physiological function of the enzyme.
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PMID:Polarographic assay and intracellular distribution of superoxide dismutase in rat liver. 81 Jan 38

The effect of Fusarium sporotrichiella v. sporotrichioides mycotoxin (sporofusarin) on the total and non-sedimentary supernatant activity of 13 marker-enzymes of subcellular particles (2 mitochondrial enzymes-cytochrome oxidase and malate dehydrogenase; 8 lysosomal enzymes -- acid phosphatase, acid RNAase, acid DNAase, arylsulphatases A and B, beta-N-acetylglucosaminidase, beta-glucuronidase, beta-galactosidase and beta-glucosidase; 2 microsomal enzymes -- glucose-6-phosphatase and acetylesterase; plasma membrane enzyme -- alkaline phosphatase) of the rat liver, kidney, spleen and bone-marrow was studied in in vivo experiments. The latter demonstrated that sporofusarin effects were characterized by a significant organ and organella specificity, viz. the toxin caused a sharply increased activity, mainly of lysosomes enzymes and labilization of the lysosomal membranes, primarily in the spleen and the bone-marrow. A conclusion is drawn that the discovered selective destructive action of sporofusarin on the lysosomes may be regarded as a new phenomenon that, possibly is directly related to the characterization of the mechanism responsible for a specific effect produced by sporofusarin.
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PMID:[Lysosomal component in the mechanism of the toxic effect of sporofusarin]. 94 27

Monoamine oxidase (MAO) increases in an age-weight relationship in the hearts of male rats. Accumulation of MAO is not related to the activities of such mitochondrial enzymes as succinic dehydrogenase or cytochrome oxidase which do not change with age. Our previous experiments, utilizing serotonin as a substrate, have determined that cardiac MAO in the young rat does not change after chemical sympathetectomy with 6-hydroxydopamine. In this study, rats of different ages were treated with 6-hydroxy-dopamine to investigate the neuronal vs. non-neuronal distribution of MAO in the heart. After sympathetectomy, various parts of the hearts and fractions of the hearts isolated by differential centrifugation were tested for changes in MAO activity with two different substrates (kynuramine and 14C-tryptamine). It was not possible to detect any changes in MAO activity in any parts or subcellular fractions of the heart as a result of denervation. Studies with clorgyline, the MAO inhibitor, in control and sympathetecomized animals revealed that rat cardiac MAO is mostly of the type A enzyme, which was originally thought to be neuronal. A histochemical technique for the electron microscopic demonstration of MAO with osmiophilic thiocarbamyl nitro blue tetrazolium was used in the rat heart in order to determine the ultrastructural location of the enzyme. Histochemical localization of MAO with the electron microscope using tryptamine as the substrate indicates that a substantial portion of rat cardiac MAO is located near the outer membranes of mitochondria within myocardial cells. This histochemical technique provides no evidence to support differential centrifugation data which suggests the presence of a sarcoplasmic reticular (microsomal) MAO in rat heart.
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PMID:Extraneuronal monoamine oxidase in rat heart: biochemical characterization and electron microscopic localization. 115 29

Exposure of chick embryos to ethanol resulted in significant alterations to the lipid composition of various different hepatic subcellular membranes. A marked decrease in cholesterol levels and an increase in the phospholipid content of microsomes and mitochondria was observed. Ethanol also affected the fatty acid profiles, mainly by decreasing the percentage of oleic acid in phosphatidylcholine and phosphatidylethanolamine in the mitochondria and phosphatidylethanolamine in the microsomes. In spite of these changes ethanol only induced alterations in the fluidity of the mitochondrial membranes, which showed a more rigid core, in contrast to the phospholipid-head region, which was not affected. In accordance with the changes observed in the physical state of the membrane, the enzymes involved in the microsomal electron-transport systems were not modified by ethanol, while cytochrome oxidase activity decreased by 50% compared to the activity in the mitochondria from control chick embryos. These findings establish that during the chick-embryo developmental period the mitochondria are more sensitive to ethanol than are the microsomes.
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PMID:Physical properties, lipid composition and enzyme activities of hepatic subcellular membranes from chick embryo after ethanol treatment. 133 37

HepG2 cells were cultured in the presence of different concentrations of cyclosporin A (CsA) or Nva2-cyclosporin (Nva2-Cs) for up to 20 days. At a low concentration (2 micrograms/ml) of CsA or Nva2-Cs, the [3H]thymidine incorporation into DNA and the rate of incorporation of [3H]leucine into total protein decreased by 20-25%. Concentrations of 10 micrograms/ml resulted in a 70% reduction of the [3H]thymidine incorporation in comparison with controls. Low concentrations of CsA resulted in mitochondria in the condensed state together with autophagosomes, large vacuoles, and elevated numbers of coated vesicles, as shown by electron microscopy. Low concentrations of Nva2-Cs resulted in swollen mitochondria, increased autophagocytosis, and increased numbers of intermediate filaments and microtubules. Higher doses of these substances (5 micrograms/ml) caused disarrangement of mitochondrial cristae, vesiculation of the endoplasmic reticulum, an elevated number of free polysomes, and accelerated autophagocytosis. Labeling of phospholipids and triglycerides with [3H]glycerol and of cholesterol and dolichol with [3H]acetate was decreased after exposure of HepG2 cells to CsA, or, in particular, Nva2-Cs. Phospholipids secreted from the cells into the medium exhibited an increased level of labeling, but the specific radioactivity of the neutral lipids in the medium was significantly decreased. Treatment of HepG2 cells with either CsA or Nva2-Cs doubled the mitochondrial cytochrome oxidase and carnitine acetyl-transferase, as well as microsomal NADPH-cytochrome c reductase activities. Such treatment also increased the cyanide-insensitive beta-oxidation of fatty acids in peroxisomes, as well as cytoplasmic DT-diaphorase and glutathione transferase activities. Prolonged treatment of the cells with CsA did not result in any cumulative effect. HepG2 cells appear to be suitable for studying the effects of cyclosporins on cellular structure and metabolism and in this system the two drugs studied here exhibited similar effects.
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PMID:Modulation of metabolism in HepG2 cells upon treatment with cyclosporin A and Nva2-cyclosporin. 164 68

Cytochrome P-450 was shown to be involved in 11 alpha-, and 11 beta-hydroxylation of Substance S in intact C. elegans protoplasts. The steroid transformation was inhibited by carbon monoxide, the inhibitory effect being dependent on CO concentration. The function of cyt P-450 in intact protoplasts was confirmed by the estimation of strong absorption at 450 nm in the CO difference spectrum. The presence of antimycin A was necessary to prevent the reduction of the cytochrome oxidase and its interference with the cyt P-450 in the spectrophotometric analysis. The intracellular content of cyt P-450 could be increased from 5.25 pM/mg protein to 26.88 pM/mg protein when the steroid inducer was present in the medium at each stage of protoplast preparation and during cyt P-450 determination. The enriched microsomal fraction obtained from the crude extract of ruptured protoplasts contained the steroid 11 alpha-hydroxylase system of C. elegans. The activity of 11 beta-hydroxylase could not be detected under the conditions of the experiment. The localization of steroid hydroxylases of C. elegans in microsomes was confirmed by cyt P-450 detection in the 9600 x g supernatant. Membranous fractions (pellets 1100 x g and 9600 x g) of the concanavaline A stabilized protoplasts, carrying the marker plasma-membrane-bound and mitochondrial ATPases, did not show maximum absorption at 450 nm in the CO difference spectrum.
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PMID:Determination of cytochrome P-450 in Cunninghamella elegans intact protoplasts and cell-free preparations capable of steroid hydroxylation. 181 23

Imidazoline-guanidinium-receptive site (IGRS) is a membrane protein that, even if recognized by a series of imidazoline and guanidinium alpha 2-adrenergic compounds, is insensitive to catecholamine and physically distinct from alpha 2 receptors (Parini, A., Coupry, I., Graham, R. M., Uzielli, I., Atlas, D., and Lanier, S. M. (1989) J. Biol. Chem. 264, 11874-11878). In the present report, we defined the subcellular localization of IGRS by performing binding studies with the imidazoline radioligand [3H]idazoxan. Binding studies on subcellular fractions of homogenates from human and rabbit liver showed a significant increase in [3H]idazoxan binding in a membrane fraction enriched in cytochrome oxidase activity, a specific marker for mitochondria. The enrichment in [3H]idazoxan binding sites correlates closely with cytochrome oxidase activity in the nuclear, mitochondrial, plasma membrane, microsomal, and soluble fractions (r = 0.966, p less than 0.002) but not with the specific markers for other cell compartments, suggesting a major localization of IGRS in mitochondria. Separation of inner and outer mitochondrial membranes by digitonin treatment showed that [3H]idazoxan binding correlates positively with monoamine oxidase (r = 0.960) and negatively with cytochrome oxidase (r = -0.950) activities. In addition, in highly purified preparations of outer mitochondrial membranes obtained by hypotonic shock, [3H]idazoxan binding activity was 12.5-fold enriched with respect to intact mitochondria. Taken together, these data show, for the first time, that IGRS in human and rabbit liver are mainly associated with the outer mitochondrial membranes. This demonstration of the major mitochondrial localization of IGRS will facilitate the characterization of its functional activity in liver.
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PMID:Subcellular distribution of imidazoline-guanidinium-receptive sites in human and rabbit liver. Major localization to the mitochondrial outer membrane. 184 63

Total and mitochondrial glycerolphosphate acyltransferase activities were measured after 24 hr exposure of rat hepatocytes to Adriamycin. Both activities decreased with increasing concentrations of Adriamycin. The activity of the microsomal glycerolphosphate acyltransferase, which was determined from the difference between the total and mitochondrial enzyme activity, also decreased with increasing drug concentration. The effect on glycerolphosphate acyltransferase was specific as there was no change in lactate dehydrogenase or cytochrome oxidase activity in this time period. Adriamycin did not inhibit mitochondrial glycerolphosphate acyltransferase activity in vitro. After 24 hr exposure of hepatocytes to Adriamycin no change was observed in the biosynthesis of phosphatidylcholine or triacylglycerol. Secretion of lipid into the medium was measured over the subsequent 24 hr. There was a significant reduction in very low density lipoprotein secretion as measured by triacylglycerol secretion from cells incubated with 5 microM Adriamycin. Cells were damaged by the 48 hr exposure to 1 microM and higher concentrations of Adriamycin as evidenced by a fall in lactate dehydrogenase activity in these cells. The secretion of lysophosphatidylcholine, as measured by the incorporation of [3H]glycerol into medium lysophosphatidylcholine, was significantly increased when cells were incubated with 5 microM Adriamycin. The results are discussed in relation to the effect of Adriamycin on hepatic lipid metabolism and the cardiotoxicity of the drug.
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PMID:The effect of adriamycin on glycerolphosphate acyltransferase and lipid metabolism in rat hepatocytes in monolayer culture. 222 13

1. The effects of dietary clofibrate (0.5%, w/w, for 10 days) on seven inbred strains of mice--C57BL/6, C57BL/B10A(5R), ATL/OLA, C3H/HE/OLA, BALB/C, CBA/CA and A/J/OLA--and three strains of rats--Sprague-Dawley, Wistar and LOU/OLA--have been investigated. Liver weight, peroxisome proliferation, catalase activity, cytosolic, microsomal and mitochondrial epoxide hydrolase activities, cytochrome oxidase activity, microsomal cytochrome P-450 content and cytosolic glutathione transferase activity in liver were determined, together with cytosolic and microsomal epoxide hydrolase and cytosolic glutathione transferase activities in the kidneys. 2. In all cases peroxisome proliferation and induction of cytosolic epoxide hydrolase were observed in livers of rodents exposed to clofibrate. Thus, no non-responsive strains were found and further evidence for a coupling between these two phenomena was provided. In many cases significant increases in the liver microsomal cytochrome P-450 content and decreases in the hepatic cytosolic glutathione transferase activity were also seen. 3. High levels of cytosolic epoxide hydrolase were found in the rat kidney. In several strains of mice and rats renal cytosolic epoxide hydrolase activity was increased by clofibrate. 4. There were often considerable strain differences. However, in general mice had higher cytosolic epoxide hydrolase and glutathione transferase activities, whereas rats had higher microsomal epoxide hydrolase activities.
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PMID:Proliferation of peroxisomes and induction of cytosolic and microsomal epoxide hydrolases in different strains of mice and rats after dietary treatment with clofibrate. 281 29

When mice were exposed to 1% 2-ethylhexanoic acid in the diet, cytosolic and microsomal epoxide hydrolase (EC 3.3.2.3) activities were increased maximally (2-2.5- and 0.5-1-fold, respectively) after 3 days. Immunochemical quantitation of these enzymes indicated that the process involved was a true induction in both cases. Maximal levels of peroxisome proliferation (as indicated by carnitine acetyltransferase activity) were obtained after 7 days of exposure. All three of these activities returned to control levels within 4 days after termination of the treatment. The liver somatic index was slightly increased after 4 days of administration of 1% 2-ethylhexanoic acid, but the protein contents of the "mitochondrial," microsomal, and cytosolic fractions were unaffected. The activity of peroxisomal palmitoyl-CoA beta-oxidation was increased 2-fold, whereas peroxisomal catalase activity was unaffected. Exposure to 2-ethylhexanoic acid also increased cytochrome oxidase activity, suggesting an effect on mitochondria. Other parameters of detoxication--i.e. total microsomal cytochrome P-450 content, cytosolic glutathione transferase activity toward 1-chloro-2,4-dinitrobenzene, and the "cytosolic" epoxide hydrolase activity localized in the "mitochondrial" fraction--were not affected by 4 days of treatment with 1% 2-ethylhexanoic acid.
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PMID:Characterization of the induction of cytosolic and microsomal epoxide hydrolases by 2-ethylhexanoic acid in mouse liver. 288 46


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