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:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

As previously reported, the membrane fraction of liquid paraffin-induced, guinea pig peritoneal macrophages exhibits an NADPH-dependent hemolytic activity toward sheep erythrocytes. This activity was inhibited with N-ethylmaleimide, superoxide dismutase, cytochrome c, catalase, desferrioxamine, mannitol, and benzoate. These inhibition profiles indicate that O2- generation by the NADPH oxidase, peroxidation of the membranous lipids with H2O2 or .OH secondarily formed from O2-, and hemolysis of sheep erythrocytes with the peroxides occur in this order in the hemolytic reaction. In fact, the lipid peroxides were found to be formed in the membrane fraction in the presence of Fe3+, subsequent to the O2- generation, and to act as a final hemolytic agent.
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PMID:The NADPH oxidase-dependent hemolysis of sheep erythrocytes with the membrane fraction of guinea pig peritoneal macrophages. 366 51

An assay to measure NADPH oxidase activity in detergent lysates of macrophage monolayers is described. The addition of a reaction mixture containing appropriate concentrations of disrupting detergents, NADPH as oxidase substrate and cytochrome c as electron acceptor, to macrophages monolayers permits the reliable detection of a superoxide dismutase-sensitive NADPH-dependent cytochrome c reductive activity. This activity is strictly substrate dependent and NADH could not substitute for NADPH. The NADPH-dependent superoxide anion-forming activity (NADPH oxidase) was investigated in different populations of human and mouse macrophages. NADPH oxidase was activated by stimulation of macrophages with phorbol-myristate acetate and activity levels correlated with ability of intact cells to produce superoxide anion. The optimal conditions for assay of NADPH oxidase were investigated and the assay was used to measure the kinetic properties of the NADPH oxidase. The assay permits investigations of the enzymatic basis of oxidative metabolism in macrophages cultivated as adherent cells without any requirements for recovery of the cells in suspension and subcellular fractionation.
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PMID:Measurement of NADPH oxidase activity in detergent lysates of human and mouse macrophage monolayers. 376 May 84

Bulk membrane fragments were prepared from cells of Bacillus cereus ATCC 4342 harvested at different stages of growth and sporulation and examined for enzymes involved in electron transport functions. The presence of succinate: DCPIP oxidoreductase (EC 1.3.99.1), succinate: cytochrome c oxidoreductase (EC 1.3.2.1), NADH:DCPIP oxidoreductase (EC 1.6.99.1), NADH:cytochrome c oxidoreductase (EC 1.6.2.1), succinate oxidase [succinate: (O(2)) oxidoreductase, EC 1.3.3.1], and NADH oxidase [NADH:(O(2)) oxidoreductase, EC 1.6.3.1] were demonstrated in membrane fragments from vegetative cells, early and late stationary-phase cells, and in cells undergoing sporulation. During the transition from a vegetative cell to a spore, there was a significant increase in the levels of enzymes associated with energy production via the electron transport system. Cytochromes of the a, b, and c type were detected in all membrane preparations; however, there was a marked increase in the level of cytochromes by the end of vegetative growth which remained throughout sporulation; there were no qualitative changes in the cytochromes throughout growth and sporulation. Sporulation was inhibited by cyanide, stressing the significance of the electron transport system. Enzyme activities were partially masked in washed membrane fragments; however, unmasking (stimulation) was achieved by sodium deoxycholate, sodium dodecyl sulfate, or Triton X-100. The degree of enzyme masking was less in vegetative cell membrane fragments than in membranes prepared from stationary-phase or sporulating cells. Results indicate the development of a membrane-bound electron transport system in B. cereus by the end of growth and prior to sporulation, which results in an increased masking of a number of enzymes associated with the terminal respiratory system of the cell.
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PMID:Development of a membrane-bound resiratory system prior to and during sporulation in Bacillus cereus and its relationship to membrane structure. 433 50

Liver microsomes of the rat contain a group of hydroxylating enzymes which are coupled to a greater or lesser degree to the electron flow system. In our studies, enzymes believed to be directly associated with the electron flow chain of NADPH, ferricyanide reduction, cytochrome c, cytochrome P-450 and substrate hydroxylation have been observed in livers obtained from normal, tumor-bearing and whole body irradiated rats as well as in Morris hepatoma 7777 and dimethyl-amino-biphenyl induced breast tumors.A significant difference appeared to exist in the activity of NADPH oxidase, NADP-ferricyanide reductase and benzopyrene hydroxylase when normal liver was compared with the liver obtained from a breast-tumor-bearing animal. Both cytochrome P-450 and cytochrome b(5) were decreased in the tumor-bearing animal.Tissue distribution of benzopyrene hydroxylase in normal, lactating and tumor-bearing Wistar rats has been studied.With the exception of NADPH oxidase, the activities of NADP-cytochrome c reductase, NADPH-ferricyanide reductase, benzopyrene hydroxylase and P-450 were markedly different in liver from Morris hepatoma 7777-bearing Buffalo rat when this was compared with homologous tissue obtained from normal Buffalo rat.Whole-body irradiated animals showed increased P-450 and NADPH oxidase activity in liver as a function of irradiation and there further appeared to be a correlation with decreased ferricyanide reductase activity.
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PMID:Mixed-function oxidation in tumors. 439 26

1. Aerobically grown yeast having a high activity of glyoxylate-cycle, citric acid-cycle and electron-transport enzymes was transferred to a medium containing 10% glucose. After a lag phase of 30min. the yeast grew exponentially with a mean generation time of 94min. 2. The enzymes malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase and NADH-cytochrome c oxidoreductase lost 45%, 17%, 27% and 46% of their activity respectively during the lag phase. 3. When growth commenced pyruvate kinase, pyruvate decarboxylase, alcohol dehydrogenase, glutamate dehydrogenase (NADP(+)-linked) and NADPH-cytochrome c oxidoreductase increased in activity, whereas aconitase, isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), alpha-oxoglutarate dehydrogenase, fumarase, malate dehydrogenase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase, NADH oxidase, NADPH oxidase, cytochrome c oxidase, glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, isocitrate lyase and glucose 6-phosphate dehydrogenase decreased. 4. During the early stages of growth the loss of activity of aconitase, alpha-oxoglutarate dehydrogenase, fumarase and glucose 6-phosphate dehydrogenase could be accounted for by dilution by cell division. The lower rate of loss of activity of isocitrate dehydrogenase (NAD(+)- and NADP(+)-linked), glutamate dehydrogenase (NAD(+)-linked), glutamate-oxaloacetate transaminase, NADPH oxidase and cytochrome c oxidase implies their continued synthesis, whereas the higher rate of loss of activity of malate dehydrogenase, isocitrate lyase, succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase and NADH oxidase means that these enzymes were actively removed. 5. The mechanisms of selective removal of enzyme activity and the control of the residual metabolic pathways are discussed.
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PMID:The kinetics of enzyme changes in yeast under conditions that cause the loss of mitochondria. 566 Jun 27

A membrane-bound NADPH-cytochrome c reductase, which is capable of forming the superoxide anion (O2-) in the presence of menadione, was highly purified from membrane fractions of disrupted guinea pig polymorphonuclear leukocytes by solubilization with 0.2% Triton X-100 and chromatographies on Sephacryl S-300 and 2',5'-ADP-agarose. The overall purification from the membrane fraction was over 110-fold, with a yield of about 6%. The purified preparation did not contain two other pyridine nucleotide-oxidizing enzymes: NADH- and NAD(P)H-oxidizing enzymes (J. Biochem. 94, 931-936, 1983). Besides cytochrome c, the purified enzyme was able to reduce menadione, Nitroblue tetrazolium (NBT) and 2,6-dichlorophenolindophenol. The reduction of menadione alone resulted in the formation of O2-. The purified enzyme preparation contained FAD. When assayed by measuring O2--generation in the presence of menadione, the enzyme showed an optimum pH at 7.0-7.4, and Km values for NADPH, NADH, and menadione were 25, 230, and 5.3 microM, respectively. The enzyme activity was not inhibited by NaN3 or dicumarol, but was by N-ethylmaleimide, EDTA, and quercetin; these inhibition profiles agree with those observed for the NADPH oxidase in the membrane fraction of phorbol-myristate acetate-stimulated leukocytes. Furthermore, when compared by means of the NBT-staining method combined with disc gel electrophoresis, the purified enzyme was electrophoretically indistinguishable from the NADPH-NBT reductase in the plasma membrane as well as phagosomes of the leukocytes. These results suggest that the purified NADPH-cytochrome c reductase is the putative flavoprotein of the NADPH oxidase system responsible for the respiratory burst.
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PMID:Purification and characterization of a membrane-bound NADPH-cytochrome c reductase capable of catalyzing menadione-dependent O2- formation in guinea pig polymorphonuclear leukocytes. 609 21

Superoxide (O-2) production by partially purified NADPH oxidase from guinea pig neutrophils was markedly increased when the cells were activated by exposure to phorbol-myristate acetate. On the contrary, NADPH-dependent cytochrome c and 2,6-dichlorophenolindophenol (DCIP) reductase activities in preparations from resting and activated neutrophils were similar. The apparent Km values for NADH and NADPH of the reductase activities were different from those of the O-2 producing enzyme. The electron acceptors did not inhibit the oxygen consumption by NADPH oxidase in the presence of superoxide dismutase. Even in anaerobiosis the oxidase failed to reduce cytochrome c and DCIP. These results suggest that NAD(P)H-dependent dye reductase activities are not involved in the electron transport system responsible for the O-2 production by neutrophils.
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PMID:NADPH oxidase of neutrophils forms superoxide anion but does not reduce cytochrome c and dichlorophenolindophenol. 632 73

Superoxide generation, assessed as the rate of acetylated cytochrome c reduction inhibited by superoxide dismutase, by purified NADPH cytochrome P-450 reductase or intact rat liver microsomes was found to account for only a small fraction of their respective NADPH oxidase activities. DTPA-Fe3+ and EDTA-FE3+ greatly stimulated NADPH oxidation, acetylated cytochrome c reduction, and O(2) production by the reductase and intact microsomes. In contrast, all ferric chelates tested caused modest inhibition of acetylated cytochrome c reduction and O(2) generation by xanthine oxidase. Although both EDTA-Fe3+ and DTPA-Fe3+ were directly reduced by the reductase under anaerobic conditions, ADP-Fe3+ was not reduced by the reductase under aerobic or anaerobic conditions. Desferrioxamine-Fe3+ was unique among the chelates tested in that it was a relatively inert iron chelate in these assays, having only minor effects on NADPH oxidation and/or O(2) generation by the purified reductase, intact microsomes, or xanthine oxidase. Desferrioxamine inhibited microsomal lipid peroxidation promoted by ADP-Fe3+ in a concentration-dependent fashion, with complete inhibition occurring at a concentration equal to that of exogenously added ferric iron. The participation of O(2) generated by the reductase in NADPH-dependent lipid peroxidation was also investigated and compared with results obtained with a xanthine oxidase-dependent lipid peroxidation system. NADPH-dependent peroxidation of either phospholipid liposomes or rat liver microsomes in the presence of ADP-Fe3+ was demonstrated to be independent of O(2) generation by the reductase.
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PMID:Superoxide generation by NADPH-cytochrome P-450 reductase: the effect of iron chelators and the role of superoxide in microsomal lipid peroxidation. 633 20

NADPH-dependent oxygen utilization by liver microsomal fractions was stimulated by the addition of increasing concentrations of butylated hydroxyanisole concomitant with the inhibition of benzphetamine N-demethylase activity. The apparent conversion of monooxygenase activity to an oxidase-like activity in the presence of the antioxidant was correlated with the partial recovery of the reducing equivalents from NADPH in the form of increased hydrogen peroxide production. The progress curve of liver microsomal NADPH oxidase activity in the presence of butylated hydroxyanisole displayed a lag phase indicative of the formation of a metabolite capable of uncoupling the monooxygenase activity. Ethyl acetate extracts of microsomal reaction mixtures obtained in the presence of butylated hydroxyanisole, oxygen, and NADPH stimulated the NADPH oxidase activity of either liver microsomes or purified NADPH-cytochrome c (P-450) reductase. Using high performance liquid chromatography, gas chromatography, and mass spectrometry techniques, two metabolites of butylated hydroxyanisole, namely t-butylhydroquinone and t-butylquinone, were identified. The quinone metabolite and/or its 1-electron reduction product interact with the flavoprotein reductase to directly link the enzyme to the reduction of oxygen which results in an inhibition of the catalytic activity of the cytochrome P-450-dependent monooxygenase.
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PMID:Butylated hydroxyanisole-stimulated NADPH oxidase activity in rat liver microsomal fractions. 641 52

Production of reactive oxygen intermediates (ROI) by the NADPH oxidase of neutrophils is a major mechanism of bacterial killing and, in pathologic circumstances, tissue damage. Integrins and selectins participate in neutrophil adhesion but may also play a role in intracellular signaling. The role of L-selectin in ROI production and Ca2+ signaling in suspended neutrophils was examined using the DREG series of anti-L-selectin antibodies. NADPH oxidase activation was assessed in three ways: H2O2 production using either scopoletin or dihydrorhodamine and O2- production using cytochrome c. Alterations in [Ca2+]i were measured using Fura 2-AM and fluorescence spectrophotometry. Cross-linking of L-selectin with DREG and 2 degrees antibody did not trigger production of H2O2 by itself but significantly enhanced the subsequent response to two soluble activating agents; the formyl peptide formyl-Met-Leu-Phe (fMLP) and tumor necrosis factor (TNF). Potentiation of the oxidative burst was observed using F(ab')2 fragments but not with irrelevant antibodies and was observed whether 2 degrees antibody was added before or after fMLP. Cross-linking of L-selectin also triggered a rise in [Ca2+]i, due, in part, to release from intracellular stores. The intracellular Ca2+ chelator BAPTA blocked both the rise in [Ca2+]i and the potentiation of the oxidative burst in response to fMLP or TNF. We conclude that cross-linking of L-selectin induces intracellular signals, including release of Ca2+, which may contribute to potentiation of the oxidative burst.
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PMID:Potentiation of the oxidative burst of human neutrophils. A signaling role for L-selectin. 751 34


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