Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.5.2 (NQO1)
 6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Simmons, R. J. (Michigan State University, East Lansing), and R. N. Costilow. Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum. J. Bacteriol. 84:1274-1281. 1962.-An investigation was made of the enzymes of vegetative cells, spores, and germinated spores of Clostridium botulinum 62-A to elucidate a pathway of glucose metabolism. Manometric studies were conducted with intact cells, and various enzymes and enzyme systems were assayed in cell-free and spore-free extracts by use of spectrophotometric and colorimetric procedures. Glucose fermentation was found to be inducible; glucokinase was the controlling enzyme. All other enzymes of the Embden-Meyerhof-Parnas (EMP) pathway were found in both induced and non-induced cells, but they were in relatively low concentrations in the latter. This, plus the fact that no glucose-6-phosphate dehydrogenase was detected, led to the conclusion that glucose is catabolized primarily by the EMP system. A number of glycolytic enzymes were also found in extracts of spores and germinated spores of this organism, but the activities were extremely low as compared with activities in cell extracts. A phosphoroclastic-type reaction was readily demonstrated in both glucose-adapted and non-adapted cells, but not in spores and germinated spores. However, both acetokinase and phosphotransacetylase, as well as coenzyme A transphorase, were detected in spores and germinated-spore extracts, although at very low activity levels as compared with cell extracts. The specific activity of diaphorase in spore extracts was about one-half that of corresponding cell extracts, and the activity of reduced diphosphopyridine nucleotide (DPNH) oxidase was actually higher in the spore extracts. In addition, the DPNH oxidase in spore extracts was considerably more heat-stable than that in extracts of cells or germinated spores.
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PMID:Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum. 1397 33

Photoautotrophically grown cells of the cyanobacterium Synechocystis sp. PCC 6803 wild type and the Ins2 mutant carrying an insertion in the drgA gene encoding soluble NAD(P)H:quinone oxidoreductase (NQR) did not differ in the rate of light-induced oxygen evolution and Photosystem I reaction center (P700+) reduction after its oxidation with a white light pulse. In the presence of DCMU, the rate of P700+ reduction was lower in mutant cells than in wild type cells. Depletion of respiratory substrates after 24 h dark-starvation caused more potent decrease in the rate of P700+ reduction in DrgA mutant cells than in wild type cells. The reduction of P700+ by electrons derived from exogenous glucose was slower in photoautotrophically grown DrgA mutant than in wild type cells. The mutation in the drgA gene did not impair the ability of Synechocystis sp. PCC 6803 cells to oxidize glucose under heterotrophic conditions and did not impair the NDH-1-dependent, rotenone-inhibited electron transfer from NADPH to P700+ in thylakoid membranes of the cyanobacterium. Under photoautotrophic growth conditions, NADPH-dehydrogenase activity in DrgA mutant cells was less than 30% from the level observed in wild type cells. The results suggest that NQR, encoded by the drgA gene, might participate in the regulation of cytoplasmic NADPH oxidation, supplying NADP+ for glucose oxidation in the pentose phosphate cycle of cyanobacteria.
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PMID:Reduction of photosystem I reaction center in DrgA mutant of the cyanobacterium Synechocystis sp. PCC 6803 lacking soluble NAD(P)H:quinone oxidoreductase. 1517 Mar 83

Mitochondrial gene knockout (rho(0)) cells that depend on glycolysis for their energy requirements show an increased ability to reduce cell-impermeable tetrazolium dyes by electron transport across the plasma membrane. In this report, we show for the first time, that oxygen functions as a terminal electron acceptor for trans-plasma membrane electron transport (tPMET) in HL60rho(0) cells, and that this cell surface oxygen consumption is associated with oxygen-dependent cell growth in the absence of mitochondrial electron transport function. Non-mitochondrial oxygen consumption by HL60rho(0) cells was extensively inhibited by extracellular NADH and NADPH, but not by NAD(+), localizing this process at the cell surface. Mitochondrial electron transport inhibitors and the uncoupler, FCCP, did not affect oxygen consumption by HL60rho(0) cells. Inhibitors of glucose uptake and glycolysis, the ubiquinone redox cycle inhibitors, capsaicin and resiniferatoxin, the flavin centre inhibitor, diphenyleneiodonium, and the NQO1 inhibitor, dicoumarol, all inhibited oxygen consumption by HL60rho(0) cells. Similarities in inhibition profiles between non-mitochondrial oxygen consumption and reduction of the cell-impermeable tetrazolium dye, WST-1, suggest that both systems may share a common tPMET pathway. This is supported by the finding that terminal electron acceptors from both pathways compete for electrons from intracellular NADH.
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PMID:Cell surface oxygen consumption by mitochondrial gene knockout cells. 1517 69

Cyclic voltammetry was successfully applied to study the oxidation of nicotinamide adenine dinucleotide (NADH) both in homogeneous and heterogeneous phase. The first case was realized with a solution containing p-methylamino-phenolsulphate (MAP) as redox mediator and the diaphorase (DI) from Clostridium kluveri as enzyme while the second one by using both a glassy carbon (GC) and a carbon nanotube paste (CNTP) electrode modified with electrodeposited films derived from 3,4-dihydroxybenzaldehyde (3,4-DHB). Such systems were successively coupled with glucose dehydrogenase (GDH) reaction to realize the redox chain present in glucose biosensors. A critical comparison of the two systems was also reported.
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PMID:A comparison between the use of a redox mediator in solution and of surface modified electrodes in the electrocatalytic oxidation of nicotinamide adenine dinucleotide. 1529 89

[reaction: see text] This study describes the design and synthesis of a novel latent fluorophore 3 for DT diaphorase based on the trimethyl lock effect and characterization of its enzymatic kinetics. Fluorophore 3 is also a sensitive fluorimetric reagent for detecting glucose when coupled with DTD and glucose dehydrogenase.
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PMID:New latent fluorophore for DT diaphorase. 1640 91

A nonradioisotope, 96-well-microplate assay to evaluate glucose uptake activity in cultured cells has been developed. 2-Deoxyglucose (2DG) was detected by measuring a potent fluorophore, resorufin, generated after incubation with a single assay solution containing hexokinase, adenosine 5'-triphosphate, glucose 6-phosphate dehydrogenase, beta-nicotineamide adenine dinucleotide phosphate, diaphorase, and resazurin. This amplifying detection system could detect the fluorescence intensity induced by uptake of 2DG into L6 skeletal muscle cells, even at the level of cells cultivated in individual wells in a 96-well microplate. Using this assay system, the effects of insulin, cytochalasin B (hexose uptake inhibitor), LY294002 (inhibitor of glucose transporter translocation), and pioglitazone hydrochloride (insulin-sensitizing agent) on 2DG uptake into L6 myotubes could be assessed clearly. Therefore, our simple method may be useful for in vitro high-throughput screening and for evaluating regulators of glucose uptake.
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PMID:A nonradioisotope, enzymatic assay for 2-deoxyglucose uptake in L6 skeletal muscle cells cultured in a 96-well microplate. 1644 89

Ascorbate is an important antioxidant in the brain. Astrocytes are capable of recycling ascorbate by taking up and then reducing its oxidation product dehydroascorbic acid (DHAA) using reducing equivalents derived from NAD(P)H. Astrocytes also contain NAD(P)H-dependent quinone reductases, such as NAD(P)H:quinone oxidoreductase (NQO1), which are capable of reducing coenzyme Q and its analogs. Short-chain coenzyme Q analogs have been proposed as therapeutic agents for neurodegenerative illnesses, but they may cause oxidative stress by non-enzymatic redox cycling or enzyme-dependent depletion of NAD(P)H. Therefore, we tested the hypothesis that the short-chain coenzyme Q analog coenzyme Q(1) (CoQ(1), ubiquinone-5) decreases intracellular NAD(P)H levels in astrocytes and impairs the ability of these cells to replace extracellular DHAA with ascorbate (i.e., ascorbate recycling). We observed that CoQ(1) inhibited the production of intra- and extracellular ascorbate by primary rat astrocytes incubated with DHAA in glucose-free medium. Reduction of CoQ(1) to CoQ(1)H(2) by astrocytes was partially blocked by the NQO1 inhibitor dicumarol but was not affected by DHAA. The inhibition of ascorbate recycling by CoQ(1) was attenuated by dicumarol and was abolished by glucose. CoQ(1) lowered intracellular levels of reactive oxygen species, as measured by oxidation of 2',7'-dichlorofluorescin but also produced marked decreases in the concentrations of NADH and NADPH. We conclude that in astrocytes CoQ(1) recycling depletes NAD(P)H and inhibits ascorbate recycling when glucose metabolism is limited. Because DHAA can cause cell-lethal oxidative stress in neurons and ascorbate produced by astrocytes may be neuroprotective, coenzyme Q analogs may adversely affect brain function through this novel mechanism.
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PMID:Coenzyme Q(1) depletes NAD(P)H and impairs recycling of ascorbate in astrocytes. 1649 85

Action and uptake of azides, nitrates, nitrites, hydroxylamines, and ammonium salts were measured on germination of Amaranthus albus, Lactuca sativa, Phleum pratense, Barbarea vulgaris, B. verna, and Setaria glauca seeds. Nitrate and nitrite reductase activities were measured in vivo for each of these kinds of seeds. Activities were measured in vitro for catalase, peroxidase, glycolate oxidase, and pyridine nucleotide quinone reductase on extracts of A. albus and L. sativa seeds before and after germination. The enzymic activities measured and the responsiveness of the haemproteins to inhibition by the several compounds indicate that nitrites, azides, and hydroxylamines promote seed germination by inhibition of H(2)O(2) decomposition by catalase. Ammonium salts showed pronounced promotive activity only for B. verna and B. vulgaris seeds, for which they served as metabolic substrates.The promotion of germination is thought to depend on coupling of peroxidase action to NADPH oxidation, which can regulate the pentose pathway of d-glucose 6-phosphate use. Pyridine nucleotide quinone reductase is the possible coupling enzyme. This enzyme and others required for the action are present in the seeds before imbibition of water.
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PMID:Promotion of seed germination by nitrate, nitrite, hydroxylamine, and ammonium salts. 1665 78

This paper describes a new amperometric biosensor for glucose monitoring. The biosensor is based on the activity of glucose dehydrogenase (GDH) and diaphorase (DI) co-immobilized with NAD(+) into a carbon nanotube paste (CNTP) electrode modified with an osmium functionalized polymer. This mediator was demonstrated to shuttle the electron transfer between the immobilized diaphorase and the CNTP electrode, thus, showing a good electrocatalytic activity towards NADH oxidation at potentials around +0.2V versus Ag|AgCl, where interfering reactions are less prone to occur. The biosensor exhibits a detection limit of 10 micromol L(-1), linearity up to 8 x 10(-4) mol L(-1), a sensitivity of 13.4 microA cm(-2)mmol(-1)L(-1), a good reproducibility (R.S.D. 2.1%, n=6) and a stability of about 1 week when stored dry at 4 degrees C. Finally, the proposed biosensor was applied for the determination of glucose in different samples of sweet wine and validated with a commercial spectrophotometric enzymatic kit.
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PMID:Development of a carbon nanotube paste electrode osmium polymer-mediated biosensor for determination of glucose in alcoholic beverages. 1717 56

The primary objective of this study was to investigate the effect of repeated sublethal doses of dimethoate (DM), an organophosphorus insecticide on glucose homeostasis, oxidative stress induction in pancreas and pancreatic damage in adult rats. Daily oral administration of DM (20 and 40 mg/kg b.w.) for 30 days induced a significant increase in blood glucose levels which was associated with impaired glucose tolerance. DM treatment resulted in elevated levels of pancreatic tissue specific markers such as activities of amylase and lipase in serum and pancreatic tissue indicating pancreatic dysfunction. Further, the activities of DT-diaphorase and NADPH-diaphorase in pancreas of DM treated rats were also found to be elevated. Interestingly, these biochemical dysfunctions were accompanied by a marked dose-related enhancement of lipid peroxidation and ROS levels in the pancreatic tissue indicating significant induction of oxidative damage. Additional evidence such as depletion in reduced glutathione levels and significant alterations in enzymic antioxidant defenses in pancreas among DM treated rats suggested induction of oxidative stress. Taken together, these findings provide experimental evidence that dimethoate at subchronic oral doses has the propensity to impair glucose homeostasis, induce significant pancreatic damage and also provide an account of the associated oxidative damage to pancreatic tissue in adult rats.
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PMID:Altered glucose homeostasis and oxidative impairment in pancreas of rats subjected to dimethoate intoxication. 1719 67


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