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:1.6.99.6 (NADPH oxidase)
10,295 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reactive microglia in the developing brain after stab wound was studied by morphological, cytochemical, and autoradiographic methods. Morphologically, early reactive cells are of the "M" cell type (Matthews 1974). They show an activated nucleus, cytoplasm rich in ribosomes with wide Golgi complex and variable numbers of lipid inclusions. Big clear vacuoles are found in many of these cells. Microtubules not associated with centrioles and filaments may or may not be present. Junctional complexes of the zonula or puncta adherentia types are occasionally found. Strong NADPH dehydrogenase, weak NADH dehydrogenase, strong ATPase, and strong acid phosphatase, in addition to nonspecific esterase activities were demonstrated in many reactive cells. Intravenous infusion of labelled bone marrow cells from a donor showed labelled macrophages and labelled perivascular cells at the site of injury. Intracerebral injection of a small dose of tritiated thymidine at the time of injury resulted in the appearance of labelled macrophages in the following days. These data suggest that many of the reactive cells have an exogenous, more probably monocytic, origin; but a certain amount of endogenous cells also act as macrophages in brain injuries.
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PMID:Reactive microglia in the developing brain. 737 29

Superoxide anion can modulate vascular smooth muscle tone and potentially affect the growth response in vascular disease. The present studies were undertaken to characterize the source of superoxide in rabbit aorta. Rings of aorta (5 mm) were incubated in physiological salt solution (PSS) for 30 min at 37 degrees C in the presence of 10 mM diethyldithiocarbamate (DDC) with or without inhibitors of superoxide-generating systems. Rings were then placed in PSS containing 250 microM lucigenin at 37 degrees C in the presence or absence of inhibitors, and changes in amounts of superoxide were determined by measuring chemiluminescence (units). The inhibitors of xanthine oxidase, oxypurinol (300 microM), and of mitochondrial NADH dehydrogenase, rotenone (50 microM), had no significant effect on superoxide levels. An inhibitor of NADPH oxidase, iodonium thiophen, caused a concentration-dependent inhibition of superoxide anion (12.49 +/- 1.48 vs 5.27 +/- 1.81 and 2.30 +/- 0.36 units, control vs 7 microM and 70 microM iodonium thiopen, respectively). A structurally related iodonium compound, diphenyleneiodonium (20 microM), caused a 78% reduction in basal and DDC-evoked superoxide levels. In the presence or absence of DDC, exogenous administration of NADPH (10 microM-1 mM), but not NADP (1 mM), elicited a concentration-dependent rise in superoxide levels that was inhibited by iodonium thiophen. Particulate fractions of whole aortic tissue exhibited NADPH-dependent superoxide production that was inhibited by 1 microM diphenyleneiodonium.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:An NADPH oxidase superoxide-generating system in the rabbit aorta. 761 77

Proinflammatory cytokines upregulate endothelial adhesion molecule expression, thereby initiating the microvascular inflammatory response. We re-evaluated the reported role of reactive oxygen metabolites (ROMs) in signalling upregulation of intercellular adhesion molecule 1 (ICAM-1) on endothelial cells by tumour necrosis factor alpha (TNF-alpha) in vitro. TNF-alpha upregulation of endothelial-cell ICAM-1 expression was inhibited by the cell-permeable antioxidants, or by the adenovirus-mediated intracellular overexpression of Cu,Zn-superoxide dismutase, but not by the exogenous (extracellular) administration of the cell-impermeable antioxidants, superoxide dismutase and/or catalase. This ICAM-1 upregulation was also inhibited by inhibitors of NADH dehydrogenase, cytochrome bc1 complex and NADPH oxidase. However, a measurable increase in net cellular ROM generation in response to TNF-alpha was not seen using four disparate sensitive ROM assays. Moreover, the stimulation of exogenous or endogenous ROM generation did not upregulate ICAM-1, nor enhance ICAM-1 upregulation by TNF-alpha. These findings suggest that an ambient background flux of ROMs, generated intracellularly, but not their net incremental generation, is necessary for TNF-alpha to induce ICAM-1 expression in endothelium in vitro.
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PMID:Ambient but not incremental oxidant generation effects intercellular adhesion molecule 1 induction by tumour necrosis factor alpha in endothelium. 956 Mar 14

An NADPH oxidase is thought to function in microglial cells of the central nervous system. These conclusions are based on pharmacological and immunochemical evidence, although these approaches are indirect and raise issues of specificity. For example, diphenyleneiodonium inhibits a variety of flavoenzymes, including xanthine oxidase, NADH dehydrogenase, and NADPH oxidase. Here, we provide genetic evidence that p47phox, an essential component of the phagocyte NADPH oxidase, is required for superoxide anion release from microglia. Microglia derived from newborn wild-type mice, but not from newborn p47phox-deficient (knockout; -/-) mice, produced superoxide after stimulation by opsonized zymosan or phorbol myristate acetate. Endogenous p47phox was detected only in wild-type microglia, consistent with selective superoxide production in these cells. Superoxide release was restored in p47phox-deficient microglia that were retrovirally transduced with human p47phox cDNA. Similar kinetics of superoxide generation were observed, consistent with the same enzyme functioning in wild-type and restored microglia. Immuno-detection of p47phox in transduced cells confirmed that restoration of superoxide release correlated with production of recombinant protein. These data provide genetic proof that p47phox is necessary for superoxide release by microglial cells and indicate that a system related to the phagocyte oxidase is active in these cells.
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PMID:Genetic requirement of p47phox for superoxide production by murine microglia. 1115 38

Respiration in cyanobacterial thylakoid membranes is interwoven with photosynthetic processes. We have constructed a range of mutants that are impaired in several combinations of respiratory and photosynthetic electron transport complexes and have examined the relative effects on the redox state of the plastoquinone (PQ) pool by using a quinone electrode. Succinate dehydrogenase has a major effect on the PQ redox poise, as mutants lacking this enzyme showed a much more oxidized PQ pool. Mutants lacking type I and II NAD(P)H dehydrogenases also had more oxidized PQ pools. However, in the mutant lacking type I NADPH dehydrogenase, succinate was essentially absent and effective respiratory electron donation to the PQ pool could be established after addition of 1 mM succinate. Therefore, lack of the type I NADPH dehydrogenase had an indirect effect on the PQ pool redox state. The electron donation capacity of succinate dehydrogenase was found to be an order of magnitude larger than that of type I and II NAD(P)H dehydrogenases. The reason for the oxidized PQ pool upon inactivation of type II NADH dehydrogenase may be related to the facts that the NAD pool in the cell is much smaller than that of NADP and that the NAD pool is fully reduced in the mutant without type II NADH dehydrogenase, thus causing regulatory inhibition. The results indicate that succinate dehydrogenase is the main respiratory electron transfer pathway into the PQ pool and that type I and II NAD(P)H dehydrogenases regulate the reduction level of NADP and NAD, which, in turn, affects respiratory electron flow through succinate dehydrogenase.
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PMID:Succinate dehydrogenase and other respiratory pathways in thylakoid membranes of Synechocystis sp. strain PCC 6803: capacity comparisons and physiological function. 1141 66

NADPH oxidase activity, in addition to NADH oxidase activity, has been shown to be present in the respiratory chain of Corynebacterium glutamicum. In this study, we tried to purify NADPH oxidase and NADH dehydrogenase activities from the membranes of C. glutamicum. Both the enzyme activities were simultaneously purified in the same fraction, and the purified enzyme was shown to be a single polypeptide of 55 kDa. The N-terminal sequence of the enzyme was consistent with the sequence deduced from the NADH dehydrogenase gene of C. glutamicum, which has been sequenced and shown to be a homolog of NADH dehydrogenase II. In addition to high NADH-ubiquinone-1 oxidoreductase activity at neutral pH, the purified enzyme showed relatively high NADPH oxidase and NADPH-ubiquinone-1 oxidoreductase activities at acidic pH. Thus, NADH dehydrogenase of C. glutamicum was shown to be rather unique in having a relatively high reactivity toward NADPH.
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PMID:NADH dehydrogenase of Corynebacterium glutamicum. Purification of an NADH dehydrogenase II homolog able to oxidize NADPH. 1173 Nov 34

Transforming growth factor-beta (TGF-beta) induces an oxidative stress process in hepatocytes that mediates its apoptotic activity. To determine the cellular source of the early reactive oxygen species (ROS) generated by fetal rat hepatocytes in response to TGF-beta, we used inhibitors that block different ROS-producing systems. Diphenyleneiodonium, which inhibits NADPH oxidase and other flavoproteins, completely blocked the increase in ROS induced by TGF-beta, coincidently with an impairment of caspase-3 activation and cell death. Rotenone, an inhibitor of the NADH dehydrogenase in mitochondrial complex I, attenuated, but did not completely inhibit, ROS-production, caspase activation, and cell death mediated by TGF-beta. No significant protection was observed with inhibitors of other ROS-producing systems, such as cytochrome P450 (metyrapone), cyclooxygenase (indomethacin), and xanthine oxidase (allopurinol). Additional experiments have indicated that two different mechanisms could be involved in the early ROS production by TGF-beta. First, an inducible (cycloheximide-inhibited) NADPH oxidase-like system could account for the extramitochondrial production of ROS. Second, TGF-beta could increase ROS by a rapid downregulation of antioxidant genes. In particular, intramitochondrial ROS would increase by depletion of MnSOD. Finally, glutathione depletion is a late event and it would be more the consequence than the cause of the increase in ROS induced by TGF-beta.
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PMID:Source of early reactive oxygen species in the apoptosis induced by transforming growth factor-beta in fetal rat hepatocytes. 1473 87

Conidia of Verticillium albo-atrum Reinke and Berthold, collected from shake cultures grown in Czapek broth, were sonified for 4 or 8 minutes or ground frozen in a mortar to obtain cell-free homogenates. These were assayed for certain enzymes associated with respiratory pathways. Malic dehydrogenase was the most active, glucose-6-P and NADH dehydrogenase were less active, NADH-cytochrome c reductase, NADPH dehydrogenase, and cytochrome oxidase were low in activity, and succinic dehydrogenase and succinic cytochrome c reductase were very low to negligible in activity. No NADH oxidase activity was detected.With the exception of NADH-cytochrome c reductase and possibly succinic dehydrogenase and cytochrome c reductase, there was no evident increase in specific activity of the enzymes during germination. Some NADH-cytochrome c reductase and a small amount of succinic-dehydrogenase and cytochrome c reductase were associated with the particulate fraction from 105,000 x g centrifugation. The other enzymes, including cytochrome oxidase, almost completely remained in the supernatant fraction.Menadione and vitamin K-S(II) markedly stimulated NADH-cytochrome c reductase activity in the supernatant fraction but had much less effect on NADPH-cytochrome c reductase in this fraction or on either of these enzyme systems in the particulate fraction. Electron transport inhibitors affected particulate NADH- and NADPH-cytochrome c reductase activity but had no effect on these in the supernatant fraction.
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PMID:Relative Activities and Characteristics of Some Oxidative Respiratory Enzymes from Conidia of Verticillium albo-atrum. 1665 81

Mitochondria isolated from pea leaves (Pisum sativum L. var Massey Gem) and purified on a linear sucrose density gradient were substantially free of contamination by Chl and peroxisomes. They showed high respiratory rates and good respiratory control and ADP/O ratios. Malate, glutamate, succinate, glycine, pyruvate, alpha-ketoglutarate, NADH, and NADPH were oxidized but little or no oxidation of citrate, isocitrate, or proline was detected. The oxidation of NADPH by the purified mitochondria did not occur via a transhydrogenase or phosphatase converting it to NADH. NADPH oxidation had an absolute requirement for added Ca(2+), whereas NADH oxidation proceeded in its absence. In addition, oxidation of the two substrates showed different sensitivities to chelators and sulfhydryl reagents, and faster rates of O(2) uptake were observed with both substrates than with either alone. This indicates that the NADPH dehydrogenase is distinct from the exogenous NADH dehydrogenase.
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PMID:Properties of substantially chlorophyll-free pea leaf mitochondria prepared by sucrose density gradient separation. 1666 78

A novel NADH dehydrogenase (NADH-dh) involving FAD as coenzyme, distinct from NADPH dehydrogenase (NADPH-dh, old yellow enzyme, EC 1.6.99.1), was found in the same cytoplasmic fraction of Gluconobacter strains. Conventional artificial electron acceptors were more effective than molecular oxygen in the NADH-dh reaction. NADH-dh did not appear to be identical with any previously described flavoproteins, although the N-terminal amino acid sequence showed 100% similarity with a non-heme chloroperoxidase. The N-terminal amino acid sequence of NADPH-dh matched 100% a putative oxidoreductase containing the old yellow enzyme-like FMN-binding domain. NADH-dh might function to regenerate NAD coupling with NAD-dependent dehydrogenases in the cytoplasm of Gluconobacter strains.
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PMID:The occurrence of a novel NADH dehydrogenase, distinct from the old yellow enzyme, in Gluconobacter strains. 1817 96


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