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)

Approved type strains of Streptococcus sanguis, S. mitis, S. mutans, and S. salivarius were grown under aerobic and anaerobic conditions. The rate of hydrogen peroxide excretion, oxygen uptake, and acid production from glucose by washed-cell suspensions of these strains were studied, and the levels of enzymes in cell-free extracts which reduced oxygen, hydrogen peroxide, or hypothiocyanite (OSCN-) in the presence of NADH or NADPH were assayed. The effects of lactoperoxidase-thiocyanate-hydrogen peroxide on the rate of acid production and oxygen uptake by intact cells, the activity of glycolytic enzymes in cell-free extracts, and the levels of intracellular glycolytic intermediates were also studied. All strains consumed oxygen in the presence of glucose. S. sanguis, S. mitis, and anaerobically grown S. mutans excreted hydrogen peroxide. There was higher NADH oxidase and NADH peroxidase activity in aerobically grown cells than in anaerobically grown cells. NADPH oxidase activity was low in all species. Acid production, oxygen uptake, and, consequently, hydrogen peroxide excretion were inhibited in all the strains by lactoperoxidase-thiocyanate-hydrogen peroxide. S. sanguis and S. mitis had a higher capacity than S. mutans and S. salivarius to recover from this inhibition. Higher activity in the former strains of an NADH-OSCN oxidoreductase, which converted OSCN- into thiocyanate, explained this difference. The change in levels of intracellular glycolytic intermediates after inhibition of glycolysis by OSCN- and the actual activity of glycolytic enzymes in cell-free extracts in the presence of OSCN- indicated that the primary target of OSCN- in the glycolytic pathway was glyceraldehyde 3-phosphate dehydrogenase.
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PMID:Hydrogen peroxide excretion by oral streptococci and effect of lactoperoxidase-thiocyanate-hydrogen peroxide. 683 37

NADPH oxidase from stimulated guinea pig granulocytes was extracted with deoxycholate. The solubilized enzyme was stable in 20% glycerol. Solubilized enzyme was free of myeloperoxidase activity. The properties of the deoxycholate solubilized enzyme indicated that it is a high molecular weight complex with a flavoprotein, calmodulin and cytochrome b possibly forming part of the complex. Maximum activity was between pH 7.0 and 7.5. The Km value was 15.8 microM for NADPH and 434 microM for NADH indicating that NADPH is the preferential substrate.
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PMID:The NADPH oxidase of guinea pig polymorphonuclear leucocytes. Properties of the deoxycholate extracted enzyme. 686 30

The relationship between glucose metabolism and the "respiratory burst" of phagocytosing polymorphonuclear leukocytes (PMN) was studied in a Renex 30-treated cell system of guinea pig PMN by a polarometric technique. Phagocytosing PMN were treated with a detergent (Renex 30) and recovery of respiratory activity was examined by addition of various concentrations of NADP and glucose-6-phosphate (G6P) to determine the availability of endogenously formed NADPH via the hexose monophosphate (HMP) pathway. The oxygen uptake by phagocytosing PMN ceased after the treatment with Renex 30 and was restored by the addition of NADP and G6P. Furthermore, the restoration of oxygen uptake was linearly proportional to the rate of NADPH formation on increase in either NADP or G6P concentration. Resting PMN showed no respiratory activity even in the presence of excess NADP and G6P, in which NADPH was formed at the same rate as in phagocytosing PMN. In a parallel experiment, recovery of respiratory activity was examined in the same system by addition of NAD and glyceraldehyde-3-phosphate (G3P) in that order to clarify whether the respiratory enzyme can utilize NADH formed via the glycolytic pathway. In contrast to the results in the NADPH-forming system, the addition of NAD and G3P induced slight oxygen uptake of Renex 30-treated PMN, but there was no difference in the oxygen uptake between resting and phagocytosis-activated PMN. The results indicated that the primary oxidase responsible for the "respiratory burst" is NADPH oxidase, and that its activity is coupled with glucose oxidation via the HMP pathway without the participation of other metabolic pathways such as glycolysis.
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PMID:Evidence that NADPH is the actual substrate of the oxidase responsible for the "respiratory burst" of phagocytosing polymorphonuclear leukocytes. 687 61

Spironolactone pretreatment (10mg/100g, twice daily for 4 days, orally) caused a significant decrease in cytochrome P-450 levels in the liver microsomes in female rats but male rats were unaffected. NADH oxidase activity was significantly decreased in both sexes by this pretreatment but NADPH oxidase and NADH cytochrome C reductase activities were not altered. NADPH cytochrome c reductase activity was increased more markedly in female rats. Despite the decrease in P-450 levels, aminopyrine N-demethylase activity was increased in female rats, while it remained unchanged in males. 7-Ethoxycoumarin O-deethylase activity was markedly increased in male and slightly decreased in female rats. The azoreductase activity was slightly reduced in treated male rats and remained unaltered in female rats when it was expressed in activity per mg microsomal protein, but the activity did show a significant increase in female rats when it was expressed as a P-450 specific rate. Sex associated differences in the effect of spironolactone on the rat liver microsomal drug metabolizing enzyme system demonstrated in the present study cannot be simply explained by the previously reported effect on adrenal and testicular steroids in male rats. It also seems unlikely that these effects were caused by an alteration in P-450 quality by selective destruction of certain species of P-450.
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PMID:Effect of spironolactone on hepatic microsomal monooxygenase and azoreductase activities. 707 90

A range of enzymatic activities in cervical mucus-secreting, ciliated and subcolumnar basal cells were assessed using light and electron microscopic cytochemical techniques. Enzymes detected in all three cell types were those of the tricarboxylic acid cycle, pentose-phosphate and glycolytic pathways, other mitochondrial associated enzymes (NADH and NADPH dehydrogenase), acid phosphatase and non-specific esterase. Mucus-secreting and ciliated cells exhibited thiamine pyrophosphatase and 5' nucleotidase activities while leucine aminopeptidase was most convincingly demonstrated in mucus-secreting cells. Alkaline phosphatase, on the other hand, was detected only in mucus-secreting and subcolumnar basal cells. The profile of enzymatic activities in subcolumnar basal cells closely resembles that of mature lining cells and further supports the hypothesis that these cells differentiate into functioning columnar cells.
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PMID:A cytochemical profile of mucus-secreting, ciliated and subcolumnar basal cells of the human cervical mucous membrane. 746 12

The dynamics and mechanisms of extracellular release of hydrogen peroxide (H2O2) from bovine pulmonary artery endothelial cells (EC) subjected to anoxia, hypoxia, and hypoxia followed by reoxygenation were examined using various inhibitors of enzymatic systems in intact cells and by direct measurement of H2O2 production from isolated EC plasma membranes. Extracellular H2O2 was measured with a fluorometric assay. EC exposed to hypoxia (3% O2) and anoxia (0% O2) released less H2O2 (29.6 +/- 1.3% and 4.2 +/- 0.7%, respectively) compared with EC exposed to normoxia (20% O2). The extracellular release of H2O2 from EC previously exposed to hypoxia for 24 h increased immediately after reoxygenation (20% O2) to 272 +/- 48%, as compared with EC exposed continuously to normoxia (100% release). Inhibition of xanthine oxidase (XO) by allopurinol did not reduce the release of H2O2 from cells exposed to normoxia or hypoxia followed by reoxygenation. Furthermore, inhibitors of cyclooxygenase (indomethacin), phospholipase A2 (quinacrine and chlorpromazine), nitric oxide synthase (L-arginine analogs), the mitochondrial electron transport chain (rotenone and cyanide), and cytochrome P-450 (methoxypsoralen) had no or minimal effect on this release. On the other hand, inhibitors of protein kinase C (calphostin and staurosporine) and NADPH oxidase (diphenyliodonium) reduced the release of H2O2 from EC in a dose-dependent manner in both exposure groups. In separate experiments, plasma membranes isolated from EC were found to produce H2O2 in the presence of NADH or NADPH as electron donors. This was inhibited by diphenyliodonium but not by allopurinol.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Release of hydrogen peroxide in response to hypoxia-reoxygenation: role of an NAD(P)H oxidase-like enzyme in endothelial cell plasma membrane. 752 30

Zidovudine (azidothymidine, AZT), a drug used in acquired immune deficiency syndrome (AIDS), blocks reverse transcriptase and therefore inhibits human immunodeficiency virus (HIV) replication. We carried out an ultrastructural and histoenzymatic study in rat cardiac muscle. Groups of animals (3 rats per group) were given drinking water with or without AZT (1 or 2 mg AZT/ml). After 30, 60 and 120 days, the hearts were studied by light and electron microscopy. Histochemical analysis of isocitrate, succinic, malic, NADH and NADPH dehydrogenase activities revealed no changes in AZT-treated rats compared with control rats. The ultrastructural study showed a disruption of cristae and an increased size of mitochondria in rats treated with AZT for 30- and 60-days. No alterations were observed in rats that received the 120-day treatment. A statistical analysis based on electron micrographs demonstrated a time-dependent ratio between intact and disrupted mitochondria. Rats that received AZT for 30 days showed a higher number of abnormal mitochondria than rats that received the 60 day treatment. No differences with respect to rat controls were observed in the rats that received AZT for 120 days. We conclude that AZT-induced ultrastructural alterations in cardiac muscle did not modify the histochemical activity of several mitochondrial enzymes.
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PMID:Histochemical and ultrastructural changes induced by zidovudine in mitochondria of rat cardiac muscle. 753 28

A 6.6 kb genomic DNA fragment from the yeast Kluyveromyces lactis was isolated. Sequence analysis of this fragment revealed the presence of two incomplete open reading frames (ORFs) in one strand, one coding for the carboxyl terminus of the plasma membrane H(+)-ATPase and the other for the amino terminus of an unidentified product. In the complementary strand, a full-length ORF which encodes for a protein homologous to the yeast NADPH-dependent Old Yellow Enzyme was found. The deduced amino acid sequence of this ORF predicts a protein of 398 residues with 84% similarity in its full length to OYE1 from Saccharomyces carlsbergensis and OYE2 from Saccharomyces cerevisiae. In addition, an internal region showed considerable similarity to the bile acid-inducible polypeptide from Eubacterium sp., to the NADH oxidase from Thermoanaerobium brockii, to the trimethylamino dehydrogenase from bacterium W3A1 and to the estrogen-binding protein from Candida albicans, suggesting a functional or structural relationship between them. Inactivation of the KYE1 (Kluyveromyces Yellow Enzyme) gene by deletion of 0.6 kb fragment between positions +358 and +936 produced viable cells with a slight increase in their generation time. Haploid cells carrying the disrupted allele showed one-third of the NADPH oxidase activity, compared to wild-type cells. Southern blotting analysis of digested DNA and chromosomes separated by contour-clamped homogeneous electric field electrophoresis from K. lactis indicated that this is a single-copy gene and it is localized on chromosome II, whose molecular size has been estimated to be approximately 1.3 Mb.
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PMID:Nucleotide sequence and chromosomal localization of the gene encoding the Old Yellow Enzyme from Kluyveromyces lactis. 759 50

The mammalian mitochondrial electron transport chain catalyzes the oxidation of NADH at pH 8.0 and pH 6.5, and the oxidation of NADPH at pH 6.5. The pH-dependencies of the rate of steady-state oxidation of NADPH and NADH by Complex I as well as by its flavoprotein fraction have been extensively studied by the laboratory of Hatefi. One model to explain these pH-dependent oxidations was proposed by Bakker and Albracht (Biochim. Biophys. Acta 850 (1986) 413-422 and 423-428, modified by Van Belzen and Albracht (Biochim. Biophys Acta 974 (1989) 311-320), which predicts that Complex I is a heterodimer with promoter B, containing FMN and Fe-S clusters 1-4 in stiochiometric amounts, catalyzing NADH oxidation at pH 8, and Protomer A, containing FMN and Fe-S clusters 2, 4, catalyzing NAD(P)H oxidation at pH 6.5. A pH-dependent transfer of electrons from protomer A Fe-S clusters 2, 4 to protomer B Fe-S clusters 2, 4 is an obligate step in the oxidation of NAD(P)H at low pH. Strict interpretation of this model allows for only three types of inhibitor: one which inhibits all three oxidase activities (type 1); one which inhibits NADH oxidase, pH 8.0 (type 4) and a third which inhibits NAD(P)H oxidase, pH 6.5 (type 5). Another possibility is that there are three separate pathways of oxidation of NAD(P)H, which would allow for a total of seven different types of inhibitor, e.g., the three types above plus type 2 inhibiting NADH oxidase pH 8.0 and pH 6.5; type 3 inhibiting NADH oxidase pH 8.0, and NADPH oxidase pH 6.5; type 6 inhibiting NADH oxidase pH 6.5; and type 7 inhibiting NADPH oxidase pH 6.5. Using a series of thirteen inhibitors of Complex I activity and the chemical modification reagent ethoxyformic anhydride (EFA), four different inhibitor types were found: seven inhibitors of type 1, four inhibitors of type 2, one inhibitor of type 3 and one inhibitor of type 4. Treatment of submitochondrial particles (SMP) with EFA abolished NADH-dependent reduction of coenzyme Q at both pH 8.0 and 6.5, while inhibiting NADPH-dependent reduction of coenzyme Q at pH 6.5 by only 30%. These results do not support the heterodimer model of Complex I electron transport of Bakker and Albracht, but do support three separate electron flow pathways through complex 1 from reduced pyridine nucleotides to coenzyme Q. A new model of electron flow through Complex I based on these finding is proposed.
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PMID:Evidence for three separate electron flow pathways through Complex I: an inhibitor study. 761 35

The signaling pathways involved in the long-term metabolic effects of angiotensin II (Ang II) in vascular smooth muscle cells are incompletely understood but include the generation of molecules likely to affect oxidase activity. We examined the ability of Ang II to stimulate superoxide anion formation and investigated the identity of the oxidases responsible for its production. Treatment of vascular smooth muscle cells with Ang II for 4 to 6 hours caused a 2.7 +/- 0.4-fold increase in intracellular superoxide anion formation as detected by lucigenin assay. This superoxide appeared to result from activation of both the NADPH and NADH oxidases. NADPH oxidase activity increased from 3.23 +/- 0.61 to 11.80 +/- 1.72 nmol O2-/min per milligram protein after 4 hours of Ang II, whereas NADH oxidase activity increased from 16.76 +/- 2.13 to 45.00 +/- 4.57 nmol O2-/min per milligram protein. The NADPH oxidase activity was stimulated by exogenous phosphatidic and arachidonic acids and was partially inhibited by the specific inhibitor diphenylene iodinium. NADH oxidase activity was increased by arachidonic and linoleic acids, was insensitive to exogenous phosphatidic acid, and was inhibited by high concentrations of quinacrine. Both of these oxidases appear to reside in the plasma membrane, on the basis of migration of the activity after cellular fractionation and their apparent insensitivity to the mitochondrial poison KCN. These observations suggest that Ang II specifically activates enzyme systems that promote superoxide generation and raise the possibility that these pathways function as second messengers for long-term responses, such as hypertrophy or hyperplasia.
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PMID:Angiotensin II stimulates NADH and NADPH oxidase activity in cultured vascular smooth muscle cells. 2431 16


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