Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rat liver nuclear envelope fraction isolated essentially by the technique of Monneron et al. (J. Cell Biol. 55, 104-125 (1972) is characterized by high levels of glucose-6-phosphatase and 5'-nucleotidase. A broadly specific nucleoside triphosphatase activity is present. Cytochromes b5 and P-450 as well as NADPH- and NADH-cytochrome c reductase activities are present but at lower levels than found in microsomes. Cytochrome c oxidase activity is low. RNA polymerase activity is absent from the nuclear envelope fraction. Cytochemistry shows that glucose-6-phosphatase activity is strong and restricted to the nuclear envelope of nuclei. 5'-Nucleotidase shows weak reaction deposit in whole nuclei but in contrast gives clear reaction deposit in isolated nuclear envelopes. Cytochemical reaction deposit due to nucleoside triphosphatase activity is not restricted to the nuclear envelope but is found to a larger extent within the nucleus.
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PMID:An enzymic analysis of a nuclear envelope fraction. 18 34

Pieces of liver (in vitro ischemia) and isolated microsomes were subjected to incubation at 4 degrees C and 37 degrees C for various time intervals. The effects on microsomal protein, phospholipids, and cholesterol and on microsomal phosphatases and electron transport enzymes were followed as a functional of time and temperature. NADH-cytochrome c reductase was very labile and was completely inactivated by 1 h, whereas G6Pase lost 50% of its activity after 2 h at 37 degrees C. IDPase and NADPH-cyt. c red. were of intermediate susceptibility whereas cytochromes b5 and P-450 were the most stable enzymes assayed. After 24 h of incubation of isolated microsomes at 37 degrees C there was no significant detachment of membrane components (protein, PLP or cholesterol), indicating that the inactivation of the enzymes was not primarily attributable to their solubilization. Instead, experiments with 14C-leucine and 14C-glycerol prelabeled microsomes demonstrated that the proteins detached from microsomes during incubation originated mainly from the intravesicular space due to repture of the microsomal membranes. The addition of a lysosomal extract during incubation did not alter either the rate of inactivation of the enzymes or the proportion of solubilized membrane components indicating that attack from the outside by proteolytic enzymes is not the mechanism for enzyme inactivation. There was no apparent correlation between the rates of inactivation of enzymes in vitro and their calculated half-lives in vivo or their postulated intramembranous localization. Ultrastructurally, enzyme inactivation was initially associated with alterations of the microsomal membranes, such as vesicle aggregation, membrane rupture, loss of unit membrane structure, and subsequently, thickening of membranes and transformation of the microsomes into nonrecognizable amorphous material.
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PMID:Effect of storage and in vitro ischemia on the ultrasture of microsomal membranes and on microsomal enzymes. 18 24

1. The electron paramagnetic resonance spectra at 15 K of reduced membrane particles of Paracoccus denitrificans exhibit resonance signals with g values, line shapes and temperature profile which are similar to the signals of the iron-sulfur centers observed in the NADH-ubiquinone segment of mitochondrial respiratory chains. These iron-sulfur centers are reducible with NADH, NADPH as well as chemically with dithionite. 2. Sulphate-limited growth of Paracoccus denitrificans results in the loss of an electron paramagnetic resonance signal (gz approximately 2.05, gy approximately gx approximately 1.92) which has properties similar to those of iron-sulfur center 2 of the NADH dehydrogenase of mitochondrial origin. The loss of this signal is accompanied by a decrease in the NADH oxidase and NADH ferricyanide oxidoreductase activities to respectively 30 and 40% of the values found for succinate-limited growth conditions. In addition respiration in membrane particles from sulphate-limited cells loses its sensitivity to rotenone. 3. Since sulphate-limited growth of Paracoccus denitrificans induces loss of site I phosphorylation [Arch. Microbiol. (1977) 112, 25-34] these observations suggest a close correlation between site I phosphorylation, rotenone-sensitivity and the presence of an electron paramagnetic resonance signal with gz approximately 2.05 and gy approximately gx approximately 1.92.
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PMID:The role of iron-sulfur center 2 in electron transport and energy conservation in the NADH-ubiquinone segment of the respiratory chain in Paracoccus denitrificans. 20 53

NADH-cytochrome c reductase, a component of benzoate 1,2-dioxygenase system, was purified to homogeneity, as judged by sodium dodecyl sulfate disc gel electrophoresis and ultracentrifugation, from benzoate-induced cells of Pseudomonas arvilla. The molecular weight of the enzyme was determined to be 38,300 by sedimentation equilibrium analysis, 37,000 by Sephadex G-100 gel filtration, and 37,500 by sodium dodecyl sulfate disc gel electrophoresis, respectively, indicating that the enzyme consisted of a single polypeptide chain. The sedimentation coefficient was calculated to be 3.3 S. The Stokes radius for the enzyme was calculated to be 27 A. The isoelectric point of the enzyme was estimated to be pH 4.2. The enzyme contained 1 mol of FAD, 2 mol of iron, and 2 mol of labile sulfide/mol of enzyme. It exhibited absorption spectrum with maxima at 273, 340, 402, and 467 nm. Amino acid analysis of the enzyme revealed that it was devoid of tryptophan. The enzyme contained 9 mol of cysteine/mol of enzyme but no disulfide linkage. The turnover number of the enzyme for the NADH-dependent reduction of cytochrome c was 17,100 at 24 degrees C. Although NADPH also acted as an electron donor, NADH was highly superior to NADPH. Ferricyanide and 2,6-dichlorophenolindophenol served as electron acceptors. Certain other properties of the enzyme are also presented.
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PMID:Characterization of NADH-cytochrome c reductase, a component of benzoate 1,2-dioxygenase system from Pseudomonas arvilla c-1. 21 33

Microsomal glucokinase is solubilized by incubation in the presence of several metabolites. After solubilization of the enzymes, the membranes present free sites for specific binding of glucokinase, therefore, they can be purified by affinity chromatography on Sepharose--ATP-glucokinase. This method yields membranous vesicles which contain, in addition to glucokinase, uridylyl-transferase, phosphoglucomutase, sialyl-transferase and adenylate cyclase. Galactosyl-transferase, glucose-6-phosphatase and NADPH cytochrome c reductase are absent. It appears that functionally related enzyme from UDP-glucose biosynthesis are aggregated onto specific patches of the membrane, most likely from Golgi apparatus.
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PMID:[Isolation by affinity chromatography of specialized membrane fractions from cat liver microsomes]. 21 51

In populations of cultured arterial endothelial and smooth muscle cells grown under the same conditions, we have measured the total activity per cell of 10 enzymes commonly used as "markers" for subcellular organelles: NADH: ferricyanide reductase, NADH:cytochrome c reductase (rotenone insensitive). NADPH:cytochrome c reductase, alpha-glucosidase, 5'-nucleotidase, alkaline phosphodiesterase I, cytochrome oxidase, monoamine oxidase, cathepsin D, and N-acetyl-beta-glucosaminidase. Significant differences between the cell types were found for 7 of the 10 enzymes tested. The total activity of 5'-nucleotidase in cultured smooth muscle cells was 17 times that of cultured endothelial cells. Comparison of the activities in the two cell types freshly collected and in culture showed that the difference in 5'-nucleotidase in cultured cells is due principally to loss of activity from endothelial cells, suggesting that this activity is regulated differently in the two cell types. In both cell types cathepsin D activity rose during culture.
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PMID:Enzyme activities in endothelial cells and smooth muscle cells from swine aorta. 22 46

Three pyridine nucleotide-dependent diaphorases have been isolated from Acinetobacter calcoaceticus cells and partially characterized. Two of them, with molecular weights of 165,000 and 57,000, utilize NADPH as electron donor whereas the third one (MW = 57,000) is specific for NADH. Oxidized viologen dyes, flavin nucleotides, dichlorophenol indophenol and ferricyanide can act with efficiency as acceptors in the reaction mediated by these diaphorases. The diaphorase activities have been characterized kinetically, and the effect of different inhibitors and cofactors has been also studied. The diaphorases seem to be subjected to metabolic control by oxidation and reduction.
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PMID:NADH and NADPH-viologen reductases from Acinetobacter calcoaceticus. 22 3

Paraquat mediates a superoxide dismutase-inhibitable reduction of cytochrome c by suspensions of Escherichia coli B. Glucose was most effective in providing electrons for this cytochrome c reduction, but other nutrients could serve in this capacity, provided the cells were preconditioned by growth on these nutrients. Paraquat reduction depended upon a NADPH:paraquat diaphorase, present in the cytosol. Reduced paraquat could diffuse across the cell envelope and react with dioxygen, in the suspending medium, thus generating O2- in that compartment. Most of the paraquat reduced in the cell, under the conditions used, reoxidized in situ and most of the O2- production was thus intracellular. The partitioning of reduced paraquat between intracellular and extracellular compartments, prior to reaction with dioxygen, depended upon intracellular pO2 and any strategy which raised intracellular pO2 decreased the efflux of reduced paraquat and thus decreased extracellular O2- production. Extracellular O2- and H2O2 did contribute to cell damage in proportion to the amount produced. O2- appeared to be unable to cross the cell envelope in either direction and the only O2- which was effective in raising the rate of biosynthesis of the manganese-superoxide dismutase, was that generated within the cell.
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PMID:Paraquat and Escherichia coli. Mechanism of production of extracellular superoxide radical. 22 55

The Co- and Ru-substituted derivatives of adrenal iron-sulfur protein (adrenodoxin) were prepared from its apoprotein in the presence of urea, dithiothreitol, Na2S, and metal ions. Both metal-substituted proteins had 2 g-atoms each of metal and labile sulfur per mole of protein. The Co derivative had optical absorption maxima at 257, 264, 470, and 1430 nm with shoulders at 275, 280, 300, and 380 nm. The molar extinction coefficient per Co atom was 2.200 M-1 cm-1 at 470 nm. The Ru derivative had a broad maximum at 500 nm with a molar extinction coefficient of approximately 100 M-1 cm-1 per Ru atom. The visible chromophore of the Co- and Ru-substituted proteins with mercurials revealed that the saturation levels are 8.6 and 8.4 mol of mercurial/mol of protein. The values agree with that of the native protein within experimental errors. The tyrosyl residue at position 82 displayed a broad anomalous emission at 335 and 331 nm for the Co- and Ru-substituted proteins, respectively, as well as in the case of the native protein. There was no electron paramagnetic resonance signal of the Co derivative in a wide magnetic field at 77 degrees K. Additionally, the Co and Ru derivatives had no enzymatic activity toward NADPH-cytochrome c reduction in the presence of adrenal diaphorase (adrenodoxin reductase). There was no indication that Mn, Ni, Cu, and Os are incorporated into the apoprotein in the presence of urea. Incorporation of Fe into the protein was examined in the presence of Co or Ru. In a system containing both Fe and Ru, Fe was exclusively incorporated into the protein. In contrast to this, the reaction products from a system containing both Fe and Co were found to consist of both Fe and Co derivatives at approximately equimolar quantity.
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PMID:Cobalt and ruthenium replacement for iron in adrenal iron-sulfur protein (adrenodoxin). Preparation and some properties. 23 19

Purified rat liver NADPH-cytochrome c reductase supports iodination of tyrosine in a system including NADPH, cytochrome c and thyroid perioxidase. Catalase inhibits the iodination of tyrosine, while superoxide dismutase has no effect. Antibody developed in the rabbit against purified rat liver NADPH-cytochrome c reductase inhibits both reduction of cytochrome c and tyrosine iodination supported by the enzyme. The antibody forms a single precipitation line with thyroid extract, and inhibits NADPH cytochrome c reductase activity of the thyroid. The antibody partially inhibits iodination in a thyroid mitochondrial-microsomal fraction, but does not inhibit NADH-dependent iodination. The immunochemical studies indicate the participation of NADPH-cytochrome c reductase in thyroidal H2O generation, and the independent existence of NADPH-dependent and NADH-dependent H2O2 generation mechanisms in the thyroid.
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PMID:Participation of NADPH-cytochrome C reductase in thyroid hormone biosynthesis. 23 16


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