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:1.6.5.2 (NQO1)
6,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rat liver postmitochondrial (S-12) fractions accounted for the bulk of the activity of whole cell homogenates in reducing chromium(VI) and accordingly in decreasing its mutagenicity. Both cytosolic (S-105) and microsomal fractions concurred to this process, which in all subcellular preparations tested was selectively induced by phenobarbital and especially by Aroclor 1254, but not by 3-methylcholanthrene. Cytosolic fractions were markedly more efficient in reducing chromium(VI) than microsomal fractions recovered from the same amount of tissue (liver or lung), although the latter preparations had a higher specific activity. The microsomal activity was exclusively NADPH dependent. A minor part of the cytosolic reduction was determined by nonenzymatic components, notably by some electron donors and chiefly by reduced glutathione, which proved to reduce chromium(VI) at physiological concentrations. However, also in cytosolic fractions, the most important contribution to chromium reduction was enzyme catalyzed, as shown by the following properties: thermolability; requirement for exogenous NADH or NADPH [supplied as such or in the form of a NADPH-generating system (S-9 mix)]; and saturation by chromium(VI). The likely involvement of DT-diaphorase in this metabolic process is supported by several findings, including its sharp pH dependence and its partial suppression by known inhibitors of this enzyme protein, such as p-chloromercuribenzoate, L-thyroxine, and dicumarol (which conversely did not counteract the metabolic deactivation of the other direct-acting mutagens 2-methoxy-6-chloro-9-[3-(2-chloroethyl)aminopropylamino]acridine 2HCl and epichlorohydrin). Similarly, cytosolic reduction of chromium(VI) was partially inhibited by selective metabolic depletors of both coenzymes of DT-diaphorase, i.e., NADPH and NADH. Pretreatment of rats with enzyme inducers (phenobarbital and 3-methylcholanthrene) stimulated the activity of DT-diaphorase in liver cytosolic fractions. A dramatic stimulation (35 to 40 times over untreated controls) was produced by Aroclor 1254, which also coinduced the liver cytosolic activity of enzymes involved in the glucose 6-phosphate-dependent pathway of both nicotinamide-adenine-dinucleotide phosphate and glutathione reduction (glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and glutathione reductase). In the lung cytosol, a slight yet significant stimulation of some of these enzyme activities was determined by the daily intratracheal instillations of high doses of chromium(VI) itself for 4 weeks, a condition which has been found to enhance the pulmonary metabolism of this metal ion.
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PMID:Prominent role of DT-diaphorase as a cellular mechanism reducing chromium(VI) and reverting its mutagenicity. 400 52

By means of the light and electron microscopy, histochemical and cytophotometrical methods the anterior subarea of the cerebral limbic cortex has been studied in 30 experimental and 30 control rabbits. The experimental animals have been given 3, 15 and 30 sessions (1 h per day) of electric irritation (0.05 mA, 50 Hz, 1 msec) on the posterior hypothalamic field (PHF). Twelve rabbits from 30 control animals make an intact group and 18--a group with inactive electrodes inserted into the PHF. After 3 and especially after 15 sessions it has been revealed: in neurons--an acute swelling, edematous alterations, hyperchromatosis and shrinkage, changes in lactate dehydrogenase, succinic dehydrogenase, nicotinamide-adenine-dinucleotide-diaphorase and nicotinamide-adenine-dinucleotide-phosphate-diaphorase activities, in neuroglia--hypertrophy and weakly manifested hyperplasia. After 30 sessions synapses degenerated after the dark type are revealed. More intensive structural and metabolic changes are noted in the middle cytoarchitectonical complex. The changes of the enzymatic activity are considered as certain signs of weakening mitochondrial processes, connected with energy production, increasing glycolysis, decreasing level of the energetic provision of the cytoplasmic synthesis, arising under conditions of a disturbed transneuronal influence on the cortex by the hypothalamus.
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PMID:[Structural and metabolic changes in the limbic cortex of the rabbit in response to experimentation with the hypothalamus]. 408 71

Total reduced nicotinamide adenine dinucleotide (NADH) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase activities were examined in human neutrophils. Approximately two-thirds of each enzyme activity was located in the granule fraction with the remainder in the soluble. The activities in a 27,000 x g supernatant from a sonic extract of human polymorphonuclear leukocytes were characterized. Both NADH and NADPH diaphorase were insensitive to cyanide and azide and showed greater activity at acid pH. K(m) values for nitroblue tetrazolium were not markedly different (33 muM with NADH and 12 muM with NADPH), but there was a 40-fold difference in K(m) for the reduced pyridine nucleotides (10 muM with NADH and 400 muM for NADPH). Since the intracellular concentration of both nucleotides is estimated to be about 50 muM, it is much more likely, from a kinetic argument, that the respiratory burst of phagocytosis is intiated by the oxidation of NADH rather than of NADPH.
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PMID:Reduced nicotinamide adenine dinucleotide and reduced nicotinamide adenine dinucleotide phosphate diaphorase activity in human polymorphonuclear leukocytes. 415 6

The cytochemical localization, by conventional methods, of lactate and glyceraldehyde-3-phosphate dehydrogenases is limited, firstly, by the solubility of these enzymes in aqueous media and, secondly, by the dependence of the final electron flow from reduced nicotinamide-adenine dinucleotide (NADH) to the tetrazolium on tissue diaphorase activity: localization is therefore that of the diaphorase, which in rabbit adductor magnus is mitochondrial. NADH has been found to have great affinity to bind in the sarcoplasmic reticulum, and, therefore, if it is generated freely in the incubation media containing 2,2',5,5'-tetra-p-nitrophenyl-3,3'-(3,3'-dimethoxy-4,4'-phenylene)-ditetrazolium chloride (TNBT) and N-methyl phenazonium methyl sulfate (PMS), it can bind there and cause a false staining. Since such a production of NADH can readily occur in the incubation media for glycolytic dehydrogenases due to diffusion of these soluble enzymes from tissue sections, the prevention of enzyme solubilization is extremely important. Fixation in formaldehyde prevented such enzyme diffusion, while at the same time sufficient activity persisted to allow for adequate staining. The incubation media contained PMS, so that the staining system was largely independent of tissue diaphorase activity. Application of these methods to adductor magnus of rabbit revealed by light microscopy, for both enzymes, a fine network which was shown by electron microscopy to represent staining of the sarcoplasmic reticulum. Mitochondria also reacted. These findings add further support for the notion that the sarcoplasmic reticulum is probably involved in glycolytic activity.
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PMID:Cytochemical localization of two glycolytic dehydrogenases in white skeletal muscle. 428 29

1. Starvation for 3 days produces a decrease in methaemoglobin-reductase and glutathione-reductase activities, but it does not alter the glucose 6-phosphate-dehydrogenase activity of the rat erythrocyte. 2. The feeding of a protein-free diet for 11 days causes greater changes in the first two enzymes and also a diminution of the third. Under this experimental condition slight decreases in protein and haemoglobin contents were noted. 3. The experimental animals did not show methaemoglobinaemia, probably because the activity of methaemoglobin diaphorase is preserved. 4. The GSH content was not affected but the stability of the tripeptide in the presence of an oxidizing agent was diminished.
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PMID:Studies on the oxidation-reduction systems of the erythrocyte. 437 99

Evidence that the bactericidal ability and the stimulated oxidative metabolism of leukocytes appear in parallel during fetal development of the Minnesota Miniature pig has been obtained by application of the techniques applied to studies of human cells. It was demonstrated that leukocytes from 87- to 90-day fetuses were fully capable of ingesting Staphylococcus aureus but greatly diminished in bactericidal capacity as compared to leukocytes of older fetuses and adults. Although resting levels of oxygen consumption and hexose monophosphate pathway activity of leukocytes from the younger fetuses compared well with those of leukocytes from older animals, the phagocytosis-stimulated increments of metabolism were much less at 87 to 90 days of gestation than at later developmental stages. Both bactericidal capacity and increased metabolism of leukocytes reach adult levels by 100 days of gestation (normal gestation period of 115 to 120 days). Acrylamide gels stained for reduced nicotinamide adenine dinucleotide (NADH) and NADH phosphate (NADPH) diaphorase activity after disc electrophoresis of leukocyte extracts revealed normal mobility and intensity of NADH diaphorase bands. Three NADPH diaphorase bands were present in adult leukocyte extracts. Only the fast-migrating NADPH diaphorase band of 87- to 90-day cells stained with decreased intensity. This "deficiency" was no longer present at the later fetal period. The fast-migrating NADPH diaphorase band may represent an electron transfer protein which functions in cyanide-insensitive respiration of the leukocytes of the pig.
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PMID:Development of bactericidal capacity and phagocytosis-associated metabolism of fetal pig leukocytes. 463

alpha-Glycerophosphate oxidase, in a strain of Streptococcus faecium, was found to be adaptive to aerated conditions of growth. The enzyme was purified and found to mediate electron transfer from alpha-glycerophosphate to O(2), with the production of stoichiometric concentrations of H(2)O(2) and dihydroxyacetone phosphate. The enzyme is an anionic flavoprotein, with flavine adenine dinucleotide as the apparent prosthetic group. By manometric methods, a K(m) of 6 x 10(-3)m, with reference to substrate concentration, was obtained. An active reduced nicotinamide adenine dinucleotide diaphorase was closely associated with this enzyme in chromatographic mobility on ECTEOLA-cellulose. The purified alpha-glycerophosphate oxidase was not inhibited by KCN, azide, or sulfhydryl reagents, nor was it stimulated by alpha-lipoate, yeast extract, or other supplements.
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PMID:Alpha-glycerophosphate oxidase in Streptococcus faecium F 24. 578 98

Bernofsky, Carl (The University of Kansas, Kansas City), and Russell C. Mills. Diaphorases from Aerobacter aerogenes. J. Bacteriol. 92:1404-1414. 1966.-Five enzymes which catalyze the reduction of 2,6-dichlorophenol-indophenol by reduced nicotinamide adenine dinucleotide (NADH(2)) have been separated from sonic extracts of Aerobacter aerogenes B199 by diethylaminoethyl (DEAE) cellulose chromatography. Three major chromatographic fractions (enzymes I, II, and III) account for most of the activity in the extract. Of the two minor fractions, one is associated with cytochrome b(1). The other is extremely labile, and was not studied further. The chromatographed diaphorases appear to have a specific requirement for flavin mononucleotide. They are also readily inactivated by dilution; however, this can be prevented by a combination of phosphate buffer, bovine serum albumin, and flavin mononucleotide. The different enzymes are clearly distinguishable by their activities with NADH(2) and reduced nicotinamide adenine dinucleotide phosphate (NADPH(2)) in the presence of various electron acceptors (2,6-dichlorophenol-indophenol, ferricyanide, menadione, and cytochrome c), and by their responses to inhibitors (amobarbital, antimycin A, Atabrine, p-chloromercuribenzenesulfonate, dicumarol, and 2,4-dinitrophenol). With 2,6-dichlorophenol-indophenol as acceptor, enzymes I, II, and III have comparable activities with either NADH(2) or NADPH(2). With menadione and ferricyanide as acceptors, enzymes II and III exhibit very high, NADH(2)-specific activities. When cytochrome c is the acceptor, however, enzyme III shows greater activity with NADPH(2) as the electron donor. Ferricyanide is the most active acceptor for the cytochrome b(1)-containing fraction. Coenzyme Q(6) does not appear to serve as an acceptor. All the diaphorases, with the exception of that in the cytochrome b(1)-containing fraction, are inhibited by p-chloromercuribenzenesulfonate. Amobarbital is relatively ineffective and inhibits only the indophenol reductase activity of enzyme I. The menadione reductase activity of enzymes I, and II, and the diaphorases in the cytochrome b(1)-containing fraction are strongly inhibited by antimycin A, 2,4-dinitrophenol, dicumarol, and Atabrine. However, the menadione reductase activity of enzyme III is affected only by the last three of these inhibitors. The diaphorases in sonic-treated extracts do not appear to be associated with a particulate fraction.
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PMID:Diaphorases from Aerobacter aerogenes. 592 71

Striatal neurons containing both somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivities have been shown to be selectively stained by the histochemical method for nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity. In the present study, we have utilized this histochemical technique to examine the morphology of these striatal neurons at the light and electron microscopic levels. Our results indicate that the striatal somatostatin/APP/NADPH-diaphorase neurons occur throughout the striatum and have long, aspiny dendrites, oval, invaginated nuclei with prominent nucleoli, and receive few axosomatic contacts. These cells appear to correspond to a population of medium-sized aspiny interneurons reported previously in Golgi and electron microscopic studies of the striatum.
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PMID:Striatal neurons containing both somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivities and NADPH-diaphorase activity: a light and electron microscopic study. 613 32

A single administration of chlorophos (trichlorophon) solution (600 mg/kg) (LD50) results in vacuolar distrophy appearing in the white rat liver and is especially pronounced in 2-4 days. Thirty minutes after the poisonous chemical is administered, butyrilcholinesterase (BChE) activity is inhibited by 90%, somewhat later oxidation-reduction enzymes activity decreases and alkaline phosphatase (APh) activity increases. Cytoplasm of hepatocytes is filled with glycogene and nearly deprived of RNA. Owing to the cytophotometric analysis of the enzymatic activity and the stereologic morphometry method, it has been possible to reveal a certain synchronism in the development of distrophic processes, in a decreasing activity of the oxidation-reduction enzymes and in a disturbed synthesis of glycogene and RNA. On the 6th day after chlorophos has been administered, succinate dehydrogenase and nicotinamide-adenine-dinucleotide-phosphate-diaphorase activity, as well as contents and distribution of RNA in hepatocytes reach their control values. BChE and APh activity does not restore. During the whole experiment there is not any statistically significant change in the volumetric part of the sinusoid capillaries and in the stellate reticuloendotheliocytes. Thus, the main effect of chlorophos action is a specific inhibition of ChE, that results in certain structural changes and in changes of the histoenzymatic parameters of the liver.
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PMID:[Morpho-functional changes in the liver after exposure to cholinesterase inhibitors]. 619 75


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