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)

The plastoquinone antagonist 2,5-dibromothymoquinone was found to inhibit NO-3 reduction from NADH by the nitrate reductase complex from wheat. It accepts electrons from NADH through the NADH dehydrogenase activity of the nitrate reductase. However, it does not inhibit the reduction of 2,6-dichlorophenol-indophenol by the enzyme. This suggests that the two compounds may be accepting electrons at different places from the enzyme. Further it was observed that reduced DCIP could be oxidized by DBMIB in the absence of NADH indicating that the electron flow in the nitrate reductase complex may take place in a unidirectional way.
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PMID:Inhibition of the nitrate reductase complex by dibromothymoquinone. 15 94

A study of the steady-state kinetics of NADH(NADPH)-cytochrome c reductase (FMN-containing) from ale yeast (M. S. Johnson and S. A. Kuby (1985) J. Biol. Chem. 260, 12341-12350) has led to a postulated three-substrate random-ordered hybrid mechanism, where NAD(P)H and FMN add randomly and very likely in a steady-state fashion, followed by an ordered addition of cytochrome c. Kinetic parameters have been derived from this mechanism. Arrhenius plots showed large differences between NADH and NADPH, as the substrate-reductant. Menadione accelerated cytochrome c reduction and also O2 uptake, but vitamin K1 and coenzyme Q10 were ineffective as electron mediators, possibly as a result of their insolubility. With NADPH as the substrate-reductant, the order of the rate of reduction of electron acceptors was ferricyanide greater than DCIP greater than cytochrome c greater than oxygen; with menadione, the specificity sequence was cytochrome c greater than ferricyanide greater than DCIP greater than oxygen. With NADH, the order was ferricyanide greater than cytochrome c greater than oxygen greater than DCIP, which changed to cytochrome c greater than ferricyanide greater than oxygen greater than DCIP on addition of menadione. Cytochrome b5 was also reduced in the absence of oxygen. No transhydrogenase activity was observed, but the reduced thionicotinamide analogs of NADH and NADPH acted as substrates. Superoxide dismutase inhibited cytochrome c reduction in air by 50%, but O2-. was not necessary for cytochrome c reduction, as evidenced by the increase in rate in the absence of O2. The product of the reaction with oxygen appeared to be H2O2.
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PMID:Studies on NADH(NADPH)-cytochrome c reductase (FMN-containing) from yeast: steady-state kinetic properties of the flavoenzyme from top-fermenting ale yeast. 308 Sep 58

At approximately equimolar concentrations (approximately 70 microM), and in the presence of excess catalase and superoxide dismutase, DCIP, ferricytochrome c and ferricyanide abstracted 21, 6 and 61%, respectively, of the electron equivalents given up by NADPH to the NADPH-O2 oxidoreductase complex derived from phorbol myristate acetate-stimulated human neutrophils. With a 10-fold increase in ferricyanide, all of the electron equivalents given up by NADPH to the oxidoreductase complex were shunted to ferricyanide concomitant with complete inhibition of NADPH-dependent O2 consumption. These results substantiate the existence of intrinsic diaphorase activity associated with the superoxide generating NADPH-O2 oxidoreductase of human neutrophils.
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PMID:Detection of NADPH diaphorase activity associated with human neutrophil NADPH-O2 oxidoreductase activity. 396 5

Four catalytic components of the NADPH-dependent O2- generating oxidoreductase of human neutrophils have been identified. DCIP reductase, cytochrome c reductase and a chromophore 450-455 reductase are present in phorbol myristate acetate stimulated neutrophils and absent in resting cells and phorbol myristate acetate stimulated chronic granulomatous disease cells. Quinol dehydrogenase activity has also been demonstrated in activated and resting cells. Furthermore, a chromophore absorbing in the reduced state at 450-455 nm participates in superoxide production. This chromophore is reduced by NADPH or duroquinol and is missing in cell lysates derived from a patient with chronic granulomatous disease.
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PMID:Delineation of the catalytic components of the NADPH-dependent O2- generating oxidoreductase of human neutrophils. 630 66

Plasma membrane oxidoreductases have been described in all cells and use extracellular impermeant electron acceptors (DCIP, Ferricyanide) that are reduced by NADH. They appear to regulate the overall cell activity in response to oxidative stress from the cellular environment. An NADH-DCIP reductase has been described at the plasma membrane of NB41A3, a neuroblastoma cell line (Zurbriggen and Dryer (1993) Biochim. Biophys. Acta 1183, 513-520) whose activation with extracellular impermeant substrates promotes cell growth. Elutriation was performed to separate cells and the various fractions were analysed for enzyme activity on intact cells combined with flow cytometry. These studies showed that the enzyme is mostly induced and activated during the G1 and during the G2/M-phases. These observations were further corroborated with specific inhibitors of the cell cycle. A three-fold increase in enzyme activity was observed in the presence of alpha-amanitin, a specific cell cycle inhibitor of the G1-phase. Taxol, a specific inhibitor of the M-phase, also induces a significant increase in enzyme activity. FACS analysis of taxol -treated and alpha-amanitin-treated cells corroborated these data. The cells have been synchronized and the enzyme activity was measured at different time intervals. An activity increase was observed after ca. 2-3 h, that corresponds to a raise in the M-phase, according to FACS data. Furthermore, NTera-2 cells - a human neuroblastoma cell line that differentiates into fully mature neurones in the presence of retinoic acid - exhibit a 50% decrease in the enzyme activity during the G0-phase upon differentiation, compared to undifferentiated cells. Together the data presented in this paper show that this plasma membrane NADH-diaphorase affects cell growth and differentiation and is strongly modulated at various phases of the cell cycle.
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PMID:The plasma membrane NADH-diaphorase is active during selective phases of the cell cycle in mouse neuroblastoma cell line NB41A3. Its relation to cell growth and differentiation. 870 90

We have investigated by immuno-electron microscopy the presence of phosphotyrosine in cells as a whole and in different cell districts (nucleus, cytoplasm, plasma membrane, and mitochondria) in peripheral blood lymphocytes of IDDM (insulin-dependent diabetes mellitus) patients and age-matched controls. Immuno-gold particle density was highest in mitochondria and decreased in cytoplasm, nucleus and plasma membrane. The time dependence of phosphotyrosine labelling after cell isolation was very strong in all subcellular populations, with a fall in immunogold staining after 30 min. Staining levels at zero time were similar in controls and IDDM patients; the loss of phosphotyrosine labelling was much stronger in controls, except in the plasma membrane. Plasma membrane NADH oxidoreductase activity, studied using cytosolic NADH as substrate and assayed with DCIP as acceptor, was significantly increased in IDDM patients, suggesting a response to a deficient mitochondrial energetic activity. The fact that NADH oxidoreductase is a growth factor related to tyrosine phosphorylation pathways raises intriguing questions on the cellular derangement occurring in peripheral lymphocytes in IDDM, although the relationships among the immunocytochemical and biochemical changes is still obscure.
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PMID:Lymphocyte dysmetabolism: an immunocytochemical comparative approach in IDDM and control subjects. 1141 69