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)

Escherichia coli K-12 was cultured under anaerobic conditions to form biofilm on carbon fiber electrodes in glucose-containing medium. The anodic current increased with the development of the biofilm and depended on the glucose concentration. Cyclic voltammetric results support the presence of a redox compound(s) excreted from E. coli cells in the biofilm. The compound remained in the film under conditions of continuous flow and gave a couple of oxidation and reduction waves, which may be assigned to a menaquinone-like compound based on the mid-point potential (-0.22 V vs Ag|AgCl at pH 7.1) and its pH dependence. The catalytic current started to increase around the anodic peak potential of the redox compound and also increased by the permeabilization of the E. coli cell membranes with ethylenediamine tetraacetic acid-treatment. The results indicate that the E. coli-excreted redox compound works as a mediator for the electron transfer from the E. coli cells to the electrode as the final electron acceptor. The activity of the redox compound in the E. coli-biofilm as a mediator with some mobility was also verified for diaphorase-catalyzed electrochemical oxidation of NADH.
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PMID:Self-excreted mediator from Escherichia coli K-12 for electron transfer to carbon electrodes. 1766 90

In the central nervous system oxidative stress has been implicated in the pathology of several neurological disorders. The ability to withstand reactive oxygen species and oxidative stress are essential for survival and therefore all aerobic cells are endowed with chemical and enzymatic antioxidative defense systems. The purpose of the present study was to investigate the antioxidative response at the transcriptional level following exposure of primary astrocytes to a pro-oxidant, Paraquat (PQ). This was done by investigating the time-dependent expression of selected genes encoding the antioxidative enzymes Mn- and CuZn superoxide dismutase (SOD) and catalase as well as the transcription factor component AP-1. Paraquat induced the expression of Mn- and CuZn SOD, catalase and decreases the expression of c-jun (a part of AP-1). Furthermore, the gene expression profiles were investigated after exposure to PQ using a commercial cDNA membrane array containing 207 genes from key oxidative stress pathways. The gene expression pattern clearly indicated that 60 microM PQ for 48 h induces genes related to oxidative stress, detoxification, mitotic arrest, DNA repair, and apoptosis. The PQ (48 h)-induced expressions of genes identified in cDNA array were confirmed by Northern blot analysis, which revealed a statistical significant up-regulation of genes involved in oxidative stress, detoxification, and DNA repair/synthesis and includes heme oxygenase-1 (11-fold), NAD(P)H dehydrogenase (8-fold), glutathione S-transferase P (7-fold), glucose-regulated 78-kDa protein (7-fold), glucose-regulated 75-kDa protein (6-fold), and growth-arrest and DNA-damage-inducible protein 45 (4.5-fold) and minor changes for heat shock 10-kDa protein, NADPH-cytochrome P450 reductase, heme oxygenase-2, proliferating cell nuclear antigen, and Bcl-2-associated death promoter. Thus, we could demonstrate a PQ-inducible effect of the mRNA of antioxidative enzymes, as well as the mRNAs of possible enzymes involved in the protection against oxidative stress.
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PMID:Characterization of the transcriptional profile in primary astrocytes after oxidative stress induced by Paraquat. 1793 86

The respiratory chain of the ethanol-producing bacterium Zymomonas mobilis is able to oxidize both species of nicotinamide cofactors, NADH and NADPH. A mutant strain with a chloramphenicol-resistance determinant inserted in ndh (encoding an NADH : CoQ oxidoreductase of type II) lacked the membrane NADH and NADPH oxidase activities, while its respiratory D-lactate oxidase activity was increased. Cells of the mutant strain showed a very low respiration rate with glucose and no respiration with ethanol. The aerobic growth rate of the mutant was elevated; exponential growth persisted longer, resulting in higher biomass densities. For the parent strain a similar effect of aerobic growth stimulation was achieved previously in the presence of submillimolar cyanide concentrations. It is concluded (i) that the respiratory chain of Z. mobilis contains only one functional NAD(P)H dehydrogenase, product of the ndh gene, and (ii) that inhibition of respiration, whether resulting from a mutation or from inhibitor action, stimulates Z. mobilis aerobic growth due to redirection of the NADH flux from respiration to ethanol synthesis, thus minimizing accumulation of toxic intermediates by contributing to the reduction of acetaldehyde to ethanol.
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PMID:NADH dehydrogenase deficiency results in low respiration rate and improved aerobic growth of Zymomonas mobilis. 1831 45

Current conventional measurement of allantoin levels in human serum uses an HPLC method. However, performing this assay is time-consuming and sample-intensive, and it requires expensive equipment. We have developed a novel enzyme cycling method for measuring allantoin concentrations in human serum. In the first step, serum allantoin is converted to allantoate by the action of allantoinase (EC 3.5.2.5), and endogenous ammonia is simultaneously removed by the action of glutamine synthetase II (EC 6.3.1.2). In the second step, l-methionine sulfoximine is used to inhibit glutamine synthetase II, and ammonia is liberated from allantoate by the activity of allantoate amidohydrolase (EC 3.5.3.9). In the final step, the ammonia is then converted to NAD by NAD synthetase (EC 6.3.1.5). Subsequent action of glucose dehydrogenase (EC 1.1.1.47) and diaphorase (EC 1.6.99.2) in the presence of glucose and 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) acts to cycle the formed NAD between its oxidized and reduced forms, resulting in the production of WST-1 formazan, which is monitored at 450 nm. The assay standard curve is linear from 0 to 70 muM allantoin. The level of allantoin in healthy subjects was measured to be 8.2+/-3.1 microM (n=30).
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PMID:An enzyme cycling method for measurement of allantoin in human serum. 1844 70

Several redox enzymes were examined for enzymatic/electrochemical-recycling systems in order to measure p-aminophenol (PAP) with high sensitivity. Glucose oxidase (GOD) and diaphorase (DI) worked well as catalysts for recycling electrode systems: these enzymes effectively reduced p-iminoquinone (PIQ), the electrochemically-oxidized form of PAP, and caused an enhancement in the electrochemical signals (anodic currents in the voltammogram and amperogram) by approximately 100 fold. The lower detection limits for PAP were estimated to be 50 nM with the GOD system and 2 nM with the DI system. We combined the enzymatic-recycling electrode using DI with an enzyme immunoassay system to measure atrial natriuretic peptide (ANP), an important marker peptide hormone involved in heart diseases. ANPs from serum samples at ppt-levels were determined appropriately using the present assay system.
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PMID:Comparison of enzymatic recycling electrodes for measuring aminophenol: development of a highly sensitive natriuretic peptide assay system. 1846 61

To better understand how the reducing power of either NADH or NADPH affects cell growth, Escherichia coli strains expressing either NADH-dependent or NADPH-dependent azoreductase (EC 1.6.5.2), which mediates the reduction of an azo dye, were cultured in glucose minimal medium in the presence of 200 muM methyl red. Growth rates in NADH-perturbed, NADPH-perturbed, and control cells were 0.05, 0.12, and 0.13 h(-1), respectively. In addition, glucose consumption in NADH-perturbed cells was 10.8 g glucose/g cell, while that of control and NADPH-perturbed cells was very similar (3.6 vs 3.8 g glucose/g cell) during the perturbation phase. Therefore, NADH perturbation had a larger effect than NADPH on cellular growth.
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PMID:Comparison of the effects of NADH- and NADPH-perturbation stresses on the growth of Escherichia coli. 1895 3

In this study, ethanol inhibited the growth and glucose-induced proton release of yeast cells in a dose-dependent manner. On the other hand, ethanol tolerance of menadione-catalyzed luminol luminescence by yeast cells increased with increasing ethanol concentrations in the growth medium. The intracellular reduced-form nicotinamide adenine dinucleotide (NADH) concentration also increased with increasing ethanol concentrations in the medium and was enough to maintain constant menadione-catalyzed luminol luminescence. These facts suggest that the menadione-catalyzed luminol luminescent assay depending on a NADH:quinone reductase and NADH generation system is useful as a new evaluation assay for assessing the vitality of ethanol-stressed yeast cells, whereas the glucose-induced proton release assay is expected to be useful for the evaluation of cell growth under ethanol stress.
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PMID:Menadione-catalyzed luminol luminescent assay as a novel evaluation method of ethanol tolerance in yeast cells. 1902 48

Brown-rot fungi such as Postia placenta are common inhabitants of forest ecosystems and are also largely responsible for the destructive decay of wooden structures. Rapid depolymerization of cellulose is a distinguishing feature of brown-rot, but the biochemical mechanisms and underlying genetics are poorly understood. Systematic examination of the P. placenta genome, transcriptome, and secretome revealed unique extracellular enzyme systems, including an unusual repertoire of extracellular glycoside hydrolases. Genes encoding exocellobiohydrolases and cellulose-binding domains, typical of cellulolytic microbes, are absent in this efficient cellulose-degrading fungus. When P. placenta was grown in medium containing cellulose as sole carbon source, transcripts corresponding to many hemicellulases and to a single putative beta-1-4 endoglucanase were expressed at high levels relative to glucose-grown cultures. These transcript profiles were confirmed by direct identification of peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Also up-regulated during growth on cellulose medium were putative iron reductases, quinone reductase, and structurally divergent oxidases potentially involved in extracellular generation of Fe(II) and H(2)O(2). These observations are consistent with a biodegradative role for Fenton chemistry in which Fe(II) and H(2)O(2) react to form hydroxyl radicals, highly reactive oxidants capable of depolymerizing cellulose. The P. placenta genome resources provide unparalleled opportunities for investigating such unusual mechanisms of cellulose conversion. More broadly, the genome offers insight into the diversification of lignocellulose degrading mechanisms in fungi. Comparisons with the closely related white-rot fungus Phanerochaete chrysosporium support an evolutionary shift from white-rot to brown-rot during which the capacity for efficient depolymerization of lignin was lost.
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PMID:Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion. 1919 60

This study demonstrated the effective application of intracellular azoreductase in mediated decolorization of azo dyes. Using the quinone reductase activity of overexpressed azoreductase AZR and quinone redox mediators, the decolorization performance of the recombinant strain Escherichia coli YB was significantly enhanced. In the presence of 0.2 mM lawsone, 75% acid red 27 (1 mM) was decolorized by E. coli YB in only 2 h, which was the highest bacterial decolorization rate ever reported. Compared to lawsone, menadione was a less effective redox mediator. Glucose was found to be the best carbon source for mediated decolorization by E. coli YB. The recombinant strain could complete four rounds of mediated decolorization repeatedly in 12 h. In addition, a 10-min pre-incubation of E. coli JM109 and activated sludge with 2-methylhydroquinone resulted in great improvement of mediated decolorization performance, which may be applied in practical treatment.
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PMID:Acceleration of azo dye decolorization by using quinone reductase activity of azoreductase and quinone redox mediator. 1920 70

The enzyme-based set-reset flip-flop memory system was designed with the core part composed of horseradish peroxidase and diaphorase biocatalyzing oxidation and reduction of redox species (2,6-dichloroindophenol or ferrocyanide). The biocatalytic redox reactions were activated by H(2)O(2) and NADH produced in situ by different enzymatic reactions allowing transformation of various biochemical signals (glucose, lactate, d-glucose-6-phosphate, ethanol) into reduced or oxidized states of the redox species. The current redox state of the system, controlled by the set and reset signals, was read out by optical and electrochemical means. The multiwell setup with the flip-flop units separately activated by various set/reset signals allowed encoding of complex information. For illustrative purposes, the words "Clarkson" and then "University" were encoded using ASCII character codes. The present flip-flop system will allow additional functions of enzyme-based biocomputing systems, thus enhancing the performance of multisignal biosensors and actuators controlled by logically processed biochemical signals. The integrated enzyme logic systems and flip-flop memories associated with signal-responsive chemical actuators are envisaged as basic elements of future implantable biomedical devices controlled by immediate physiological conditions.
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PMID:Set-reset flip-flop memory based on enzyme reactions: toward memory systems controlled by biochemical pathways. 1990 97


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