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)

The effects of antibiotics and other commonly used medications on the human polymorphonuclear neutrophil leukocytes' (PMNs) nicotinamide-adenine dinucleotide phosphate-reduced (NADPH) oxidase activity have been investigated in vitro. Five antibiotics (penicillin G sodium, cefamandole nafate, metronidazole hydrochloride, clindamycin phosphate, and tobramycin sulfate, and a triple combination of penicillin G sodium-metronidazole hydrochloride-tobramycin sulfate) and two sedatives (morphine sulfate and diazepam) were incubated with normal human PMNs at therapeutic, infratherapeutic, and supratherapeutic drug levels. The superoxide dismutase-inhibitable, NADPH-dependent reduction of cytochrome C in the PMNs was studied after stimulation with formyl-methionyl-leucine-phenylalanine. Tobramycin sulfate and the triple combination of penicillin G sodium-metronidazole hydrochloride-tobramycin sulfate significantly reduced the NADPH oxidase activity at all dosages studied. Clindamycin phosphate, morphine sulfate, and diazepam also showed significant reduction at therapeutic and supratherapeutic concentrations. Penicillin G sodium, cefamandole nafate, and metronidazole hydrochloride did not cause a decrease in enzyme activity at any levels tested. We conclude that NADPH oxidase activity can be adversely affected by the circulating levels of common antibiotics and sedatives.
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PMID:Effect of antibiotics and sedatives on normal neutrophil nicotinamide-adenine dinucleotide phosphate-reduced oxidase activity. 394 1

The extracellular protein coat of the sea urchin egg is cross-linked after fertilization via dityrosyl linkages made by an exocytosed ovoperoxidase. The source of oxidant for this reaction is unknown, but eggs produce H2O2 in amounts equivalent to the cyanide-insensitive O2 uptake "respiratory burst" that follows fertilization. Several possible H2O2-forming oxidase activities, including glucose, xanthine, fatty acyl, and fatty-acyl CoA oxidases, were absent from the egg cortex. However, an NAD(P)H-O2 oxidoreductase activity was found in the egg cortex and was completely accounted for by ovoperoxidase. Homogeneous ovoperoxidase exhibits two types of NAD(P)H oxidase activity. One of these activities is similar to that of horseradish peroxidase and lactoperoxidase; it is dependent on Mn2+ ions and catalytic amounts of phenols, such as 2,4-dichlorophenol and N-acetyltyrosinamide, and is greater than 95% inhibited by 0.1 mM cyanide. A second, novel oxidase activity utilizes Ca2+ and an unidentified, heat-stable, Mr less than 1000 factor that can be extracted by ethanol from egg homogenates. This NADH oxidase activity is only 40% inhibited by 0.1 mM cyanide and is maximally stimulated by 10 mM Ca2+. It has an apparent Km for NADH of 50 microM. The stoichiometry of NADH:O2 consumption is 1.6:1, but approaches 2:1 in the presence of 20 micrograms/ml superoxide dismutase or 200 micrograms/ml catalase. This indicates that complete reduction of O2 to water occurs and that the reaction does not produce H2O2 stoichiometrically. However, nearly complete inhibition of the reaction by higher catalase concentrations suggests that H2O2 is an intermediate. The properties of this novel oxidase activity suggest that it may play such a role in vivo.
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PMID:The relationship between a novel NAD(P)H oxidase activity of ovoperoxidase and the CN- -resistant respiratory burst that follows fertilization of sea urchin eggs. 405 35

The origin of luminol-dependent chemiluminescence (CL) in neutrophils stimulated by immune complexes (IC) was investigated. It was found that CL induced by soluble IC and aggregated human gamma globulin (AHG) was glucose-independent, while insoluble IC-induced CL was diminished in the absence of glucose. AHG-induced CL was not inhibited by superoxide dismutase, catalase or 2,5-dimethyl furan, but was suppressed in the presence of phenol, sodium benzoate, sodium formate and mannitol. The CL was also inhibited by inhibitors of arachidonic acid (AA) metabolism including 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, quinacrine, indomethacin and aspirin, and by prostaglandins E1 and E2, theophylline and dibutyryl cyclic AMP. Luminol-dependent CL was also studied in cell-free systems including AA plus soybean lipoxygenase, hydroperoxyeicosatetraenoic acid plus peroxidase and xanthine oxidase plus xanthine. Our results indicate that, in neutrophils exposed to soluble IC and AHG, CL is produced and this is closely linked to the formation of free radicals during the metabolism of AA. The radical(s) involved is likely to include the hydroxyl radical. In neutrophils stimulated by large aggregates of IC or micro-organisms, superoxide anion, H2O2 and singlet oxygen are also produced as a result of activation of NAD(P)H oxidase. These oxygen species function as oxidizing agents for AA metabolism and amplify the production of hydroxyl radical along the lipoxygenase (and possibly cyclooxygenase) pathway(s).
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PMID:Luminol-dependent chemiluminescence produced by neutrophils stimulated by immune complexes. 608 70

Human peripheral blood leukocytes, activated by phorbol myristate acetate, disrupt canine sarcoplasmic reticulum calcium transport, in vitro, by an oxygen-derived free radical mechanism. Activated leukocytes significantly depress Ca++ uptake activity and Ca++ -stimulated, Mg++ -dependent ATPase activity. The depression is completely inhibited by sodium-azide (0.1 mM) or the combination of superoxide dismutase (10 micrograms/ml) and catalase (10 micrograms/ml). Exogenous hydrogen peroxide (0.441-4.41 mM) uncoupled Ca++ uptake activity from ATP hydrolysis, and this effect was inhibited by catalase. Mannitol alone did not inhibit the effects of activated leukocytes, but superoxide plus mannitol (20-100 mM) resulted in normal ATPase activity, while Ca++ uptake remained depressed. In the presence of indomethacin and ibuprofen, activated leukocytes depressed Ca++ uptake and had no effect on ATPase activity. 2-Amino-methyl-4-t-butyl-6-iodophenol (MK-447) further depressed Ca++ uptake and partially inhibited the effect on ATPase activity. Indomethacin plus catalase completely inhibited the effects of activated leukocytes on cardiac sarcoplasmic reticulum. We conclude, first, that activated leukocytes depress canine cardiac sarcoplasmic reticulum Ca++ transport by an oxygen-free radical mechanism with the generation of hydrogen peroxide and hydroxyl radical. In addition to the classical membrane NADPH oxidase system, significant oxygen radical generation can occur through the cyclooxygenase pathway of arachidonic acid metabolism, and seems to be responsible for the generation of the hydroxyl radical.
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PMID:Hydrogen peroxide and hydroxyl radical mediation of activated leukocyte depression of cardiac sarcoplasmic reticulum. Participation of the cyclooxygenase pathway. 613 70

Phorbol myristate acetate activated in normal human neutrophils a single enzymatic entity that was dormant in unstimulated cells, optimally active at pH 7.0, and capable of oxidizing either NADH or NADPH, producing NAD(P)+ and superoxide (O27). Comparative fluorometric and spectrophotometric measurements supported the stoichiometry NAD(P)H + 20(2) leads to NAD(P)+ + 20(27) + H+. the seemingly considerable NAD(P)+ production at pH 5.5 and 6.0 was due largely to nonenzymatic oxidation of NAD(P)H by chain reactions initiated by HO27 (perhydroxyl radical), the conjugate acid of O27. This artifact, responsible for earlier erroneous assignments of an acid pH optimum for NAD(P)H oxidase, was prevented by including superoxide dismutase in fluorometric assays. NAD(P)H oxidase was more active towards NADPH (Km = 0.15 +/- 0.03 mM) than NADH (Km = 0.68 +/- 0.2 mM). No suggestion that oxidase activity was allosterically regulated by NAD(P)H was seen. Phorbol myristate acetate-induced O27 production was noted to be modulated by pH in intact neutrophils, suggesting that NAD(P)H oxidase is localized in the plasma membrane where its activity may be subject to (auto) regulation by local H+ concentrations.
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PMID:NAD(P)H oxidase activity in human neutrophils stimulated by phorbol myristate acetate. 625 12

Kupffer cells were isolated from pronase-perfused rat livers and were maintained as a monolayer culture in a state of high purity and viability. Immediately after contact with zymosan particles, O2 uptake of the Kupffer cells increased fivefold; about 50% of the net oxygen consumed was accounted for as superoxide released into the medium. Concomitantly, a transient burst of luminol-dependent chemiluminescence, an increased activity of NAD(P)H oxidase and a stimulation of the flow of glucose through the hexose monophosphate shunt were observed. Chemiluminescence and O2- production were almost completely inhibited by superoxide dismutase and iodoacetate. Zymosan-induced chemiluminescence was not inhibited in the presence of the non-penetrating thiol reagents, 5,5'-dithio-bis-2-nitrobenzoate and iodoacetyl-sepharose. Iodoacetate acted on the cytosolic glucose-6-phosphate dehydrogenase rather than on NAD(P)H oxidase of the cell membrane.
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PMID:Superoxide release by zymosan-stimulated rat Kupffer cells in vitro. 628 Oct 2

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

This article gives a synopsis of the inflammatory reactions as well as its mediators under special consideration of the efferent part of the reaction. There is no doubt that histamine, complement, and the kinin system play an essential role; arachidonic acid (eicosatetraenic acid) and its metabolites, however, have gained comparable significance: prostaglandines, prostacyclines, and thromboxanes as metabolites of the cyclo-oxygenase, the leucotrienes SRS-A (slow reacting substances of anaphylaxis) and ECF (eosinophilic chemotactic factor) mediated via lipoxygenase. Moreover, oxygen and its metabolites hydrogen peroxide (H2O2), peroxide radicals (O-2), and hydroxyl radicals (.OH) as well as activated oxygen (singulett oxygen (1O2) play an important part with all aerobic living organisms. Inborn enzyme deficiency of the oxygen metabolism such as NADPH oxidase or cytochrome b-245 deficiency lead to chronic septic granulomatosis. The disease is characterized by reduced resistence against infections, decreased phagocytosis, insufficient killing of bacteria by leucocytes, and diminished oxygen burst. Thus the underlying enzyme deficiency leads to reduced formation of peroxide radicals frequently causing infections with septic complications. On the other hand, increased formation or reduced degradation of peroxide radicals may result in pathological reactions like chromosomal alterations, lipidperoxidation or oxidation of sulph-hydryl groups. The fact that increased peroxide radical formation may cause inflammation or chromosomal aberration is of importance with regard to the pathogenesis of several chronic inflammatory diseases of unknown etiology, such as systemic scleroderma or lupus erythematodes. The enzyme superoxide dismutase (SOD) converts peroxide radicals (O-2) into hydrogen peroxide (H2O2) which can be inactivated by catalase or peroxidase. Consequently, treatment with SOD may have an effective influence on chronic inflammatory dermatoses of unknown pathogenesis.
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PMID:[Biochemical aspects of the inflammatory reaction - with special reference to oxygen]. 666 95

The luminol-dependent chemiluminescence (CL) of neutrophils phagocytosing zymosan is inhibited by superoxide dismutase (SOD), catalase, sodium benzoate, and 2,5-dimethyl furan. In the present report it is shown that inhibition by SOD and 2,5-dimethyl furan is diminished and removed, respectively, by the omission of glucose from the incubation medium. Zymosan-induced CL is also inhibited by inhibitors of arachidonic acid (AA) metabolism, including 5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, quinacrine, indomethacin, and aspirin, by prostaglandins E1 and E2, theophylline, and dibutyryl cyclic AMP (cAMP), and by the addition of AA, sodium fluoride, and xanthine oxidase plus xanthine to the cell suspension. These findings lead us to postulate that the metabolism of AA via the lipoxygenase (and cyclooxygenase) pathway(s) is the source of CL observed in neutrophils after phagocytosis. Reactive oxygen species produced as a result of activation of NAD(P)H oxidase provide oxidizing agents for the oxidation of AA along these pathways. It is also suggested that elevated levels of cAMP induced by prostaglandins synthesized via the cyclooxygenase pathway may play a role in the regulation of the zymosan-induced CL response.
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PMID:The origin of chemiluminescence produced by neutrophils stimulated by opsonized zymosan. 668 3


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