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)

Treatment of submitochondrial particles (ETP) with trypsin at 0 degrees destroyed NADPH leads to NAD (or 3-acetylpyridine adenine dinucleotide, AcPyAD) transhydrogenase activity. NADH oxidase activity was unaffected; NADPH oxidase and NADH leads to AcPyAD transhydrogenase activities were diminished by less than 10%. When ETP was incubated with trypsin at 30 degrees, NADPH leads to NAD transhydrogenase activity was rapidly lost, NADPH oxidase activity was slowly destroyed, but NADH oxidase activity remained intact. The reduction pattern by NADPH, NADPH + NAD, and NADH of chromophores absorbing at 475 minus 510 nm (flavin and iron-sulfur centers) in complex I (NADH-ubiquinone reductase) or ETP treated with trypsin at 0 degrees also indicated specific destruction of transhydrogenase activity. The sensitivity of the NADPH leads to NAD transhydrogenase reaction to trypsin suggested the involvement of susceptible arginyl residues in the enzyme. Arginyl residues are considered to be positively charged binding sites for anionic substrates and ligands in many enzymes. Treatment of ETP with the specific arginine-binding reagent, butanedione, inhibited transhydrogenation from NADPH leads to NAD (or AcPyAD). It had no effect on NADH oxidation, and inhibited NADPH oxidation and NADH leads to AcPyAD transhydrogenation by only 10 to 15% even after 30 to 60 min incubation of ETP with butanedione. The inhibition of NADPH leads to NAD transhydrogenation was diminished considerably when butanedione was added to ETP in the presence of NAD or NADP. When both NAD and NADP were present, the butanedione effect was completely abolished, thus suggesting the possible presence of arginyl residues at the nucleotide binding site of the NADPH leads to NAD transhydrogenase enzyme. Under conditions that transhydrogenation from NADPH to NAD was completely inhibited by trypsin or butanedione, NADPH oxidation rate was larger than or equal to 220 nmol min-1 mg-1 ETP protein at pH 6.0 and 30 degrees. The above results establish that in the respiratory chain of beef-heart mitochondria NADH oxidation, NADPH oxidation, and NADPH leads to NAD transhydrogenation are independent reactions.
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PMID:Oxidation of NADPH by submitochondrial particles from beef heart in complete absence of transhydrogenase activity from NADPH to NAD. 0 Mar 95

Mitochondria may be isolated from various types of leukocyte (neutrophil polymorphs and lymphocytes from human blood, neutrophil polymorphs and macrophages from peritoneal exudates of the guinea pig) after destruction by heparin of the cell membrane. This procedure is very simple and less traumatic for these subcellular structures than the usual mechanical procedures. The enzyme activities of the respiratory chain and oxygen consumption may be measured in these mitochondrial preparations. The oxygen consumption is determined using oxyhemoglobin which serves both as oxygen donor, as in the respiratory system in vivo, and as indicator of the reaction at 435.8 nm. The integrity of the mitochondria may be demonstrated by determination of the "acceptor control index", the existence of ADP phosphorylation coupled with oxygen consumption (phosphorylating oxidation) was proved in all the cells studied even if the ADP/O ratio can only be calculated for certain of them (lymphocytes, macrophages). In these cases, the ratios obtained are close to theoretical values whatever the oxidation substrate used. The mitochondria of leukemic cells have a higher oxidation activity than the corresponding reference cells. Determination of leukocyte coenzymes by enzyme cycling (NAD, NADH, NADP, NADPH) showed the following facts: -- Generally, the NAD concentrations remain constant, those of NADH increase whilst those of NADP and NADPH fall during incubation of neutrophil polymorphs in Dulbecco's medium. -- The metabolic changes observed during S. albi heat-induced endocytosis are in favour of simultaneous stimulation of NADH oxidase and NADPH oxidase in human polymorphs, and of NADPH oxidase in the corresponding cells of peritoneal exudates in guinea pigs.
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PMID:[Enzyme system and coenzymes involved in the energy metabolism of leukocytes. Function and metabolism of polymorphonuclear neutrophils]. 0 34

Hepatic microsomes from rats fed a crude or a purified diet were compared by measureing their contents of protein, cytochrome P-450, and cytochrome b5, their rates of activity of NADPH- and NADH-cytochrome c reductases, NADPH-cytochrome P-450 reductase, NADPH oxidase, lipid peroxidase, ethylmorphine N-demethylase, aniline hydroxylase, benzpyrene hydroxylase, and their substrate-binding spectra (ethylmorphine, hexobarbital, aniline, and ethyl isoyanide). With the exception of lipid peroxidase activity, which was much higher in microsomes from animals fed the crude diet, little or no consistent diet-related differences in these measurements were observed over a 4-week experimental period, nor were results significantly less variable with one or the other diet. No consistent significant differences were observed with two strains of rats. The lower lipid peroxidase activity seen with the purified diet appeared to be due to the high vitamin E intake when that diet was employed; rats fed the crude diet and an oral supplement of alpha-tocopherol yielded microsomes with low lipid peroxidase activities similar to those seen in microsomes from rats fed the purified diet. A gradual temporal increase in benzpyrene hydroxylase activity was observed with both diets. This was interpreted to be due to environment inducing agents other than those present in the diet.
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PMID:Comparison of hepatic microsomal drug-metabolizing systems from rats fed crude and purified diets. 0 25

1. Inhibition of endogenous microsomal NADPH oxidase by CO enables membrane-bound glutathione-insulin transhydrogenase (EC 1.8.4.2) to be assayed conveniently by a linked assay involving NADPH and glutathione reductase (EC 1.6.4.2). 2. The specific activity of the enzyme in rat liver microsomal preparations is of the order of 1 nmol of oxidized glutathione formed/min per mg of membrane protein. 3. The specific activity of the enzyme is comparable in rough and smooth microsomal fractions, and the activity is not affected by treatment with EDTA and the removal of ribosomes from rough microsomal fractions. 4. Membrane-bound glutathione-insulin transhydrogenase is not affected by concentrations of deoxycholate up to 0.5%, whereas protein disulphide-isomerase (EC 5.3.4.1) is drastically inhibited. 5. On these grounds it is concluded that, in rat liver microsomal fractions, glutathione-insulin transhydrogenase and protein disulphide-isomerase activities are not both catalysed by a single enzyme species.
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PMID:Thiol-protein disulphide oxidoreductases. Assay of microsomal membrane-bound glutathione-insulin transhydrogenase and comparison with protein disulphide-isomerase. 1 83

NADPH oxidase activity was examined in paired 27,000 x g granule fractions isolated from normal polymorphonuclear leukocytes from patients with chronic granulomatous disease. At 0.17 mM NADPH, the oxidase activity was not measurable in normal resting cells but was activated by phagocytosis. This activation was absent in CGD cells. At higher levels of NADPH, activity was present in cells from patients with CGD, although it was lower than normal, and no difference in activity was found between resting and phagocytizing cells. Granule fractions from phagocytizing normal cells exhibited higher than granule fractions from resting normal cells at all levels of NADPH. These results suggest that NADPH oxidase activity is defective in chronic granulomatous disease, and further that the defect is not the absence of the enzyme but rather a failure to activate it.
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PMID:Deficiency of NADPH oxidase activity in chronic granulomatous disease. 1 54

Cyanide has been shown to stimulate both oxygen uptake and hexose monophosphate shunt activity in phagocytizing human polymorphonuclear leukocytes. It also stimulates the oxidation of NADPH by a particulate fraction derived from phagocytizing cells. This stimulation of NADPH oxidase is not observed in the presence of exogenous Mn2+. Studies with purified enzymes have shown that CN- also stimulates NADPH oxidation by horseradish peroxidase or lactoperoxidase, suggesting that the respiratory burst might be initiated by activation of a peroxidase-like enzyme in the human polymorphonuclear leukocyte. Based on studies of others, however, it does not appear as though the enzyme is identical to myeloperoxidase. The mechanism of the CN- stimulation appears to involve an oxidatic chain reaction, since it stimulates markedly NADPH oxidation in the presence of an artificial superoxide-generating system.
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PMID:Effect of cyanide on NADPH oxidation by granules from human polymorphonuclear leukocytes. 1 79

On the basis of inhibition studies of the dealkylation of morphine and norcodeine, George and Tephly concluded that O-dealkylation and N-dealkylation are catalyzed by different enzymes. We have examined the microsomal dealkylation of 3-O-[1'-14Clethylmorphine by measuring HCHO colorimetrically and [1-14C]acetaldehyde radiometrically. We find that the KM for the O-de-ethylation is 57 muM, which is quite close to the KS(71 muM) for the type I binding of ethylmorphine in similar preparations. On the other hand, the KM for N-demethylation was 250 muM. Further, the N-demethylation was stoichiometric with the stimulation of both NADPH-cytochrome P-450 reductase and NADPH oxidase, whereas the sum of the N-demethylation and O-de-ethylation was significantly greater, suggesting that the O-de-ethylase activity does not involve stimulation of either of these two activities. Induction with phenobarbital increaesed N-demethylation 118% but did not affect O-de-ethylation. Finally, D2O inhibited the N-demethylase more than the O-de-ethylase.
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PMID:Studies on the N-demethylation and O-de-ethylation of ethylmorphine by hepatic microsomes from male rats. 1 81

The determination of the coenzymes NAD+, NADH, NADP+ and NADPH, by the use of a method of enzymatic cycling, demonstrates that the enzymes responsible for the stimulations found during the phagocytosis of Staphylococcus albus are NADH and NADPH oxidase of human leukocytes and NADPH oxidase in the case of guinea pig leukocytes. The effects of serum, of the bacterial strain used and of phospholipase C are also discussed.
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PMID:The energy metabolism of the leukocyte. IX. Changes in the concentration of the coenzymes NAD, NADH, NADP, and NADPH in polymorphonuclear leukocytes during phagocytosis of Staphylococcus albus and due to the action of phospholipase C. 1 47

1. Oxidation of NADPH by various acceptors catalyzed by submitochondrial particles and a partially purified NADH dehydrogenase from beef heart was investigated. Submitochondrial particles devoid of nicotinamide nucleotide transhydrogenase activity catalyze an oxidation of NADPH by oxygen. The partially purified NADH dehydrogenase prepared from these particles catalyzes an oxidation of NADPH by acetylpyridine-NAD. In both cases the rates of oxidation are about two orders of magnitude lower than those obtained with NADH as electron donor. 2. The kinetic characteristics of the NADPH oxidase reaction and reduction of acetylpyridine-NAD by NADPH are similar with regard to pH dependences and affinities for NADPH, indicating that both reactions involve the same binding site for NADPH. The binding of NADPH to this site appears to be rate limiting for the overall reactions. 3. At redox equilibrium NADPH and NADH reduce FMN and iron-sulphur center 1 of NADH dehydrogenase to the same extents. The rate of reduction of FMN by NADPH is at least two orders of magnitude lower than with NADH. 4. It is concluded that NADPH is a substrate of NADH dehydrogenase and that the nicotinamide nucleotide is oxidized by submitochondrial particles via the NADH--binding site of the enzyme.
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PMID:The mechanism of oxidation of reduced nicotinamide dinucleotide phosphate by submitochondrial particles from beef heart. 2 68

Isopycnic sedimentation has been used to separate granulocytes of varying stages of maturity from the bone marrows of normal rabbits and rabbits stimulated to undergo an intense inflammatory response. The separated cell populations were in turn utilized to study the specific activities of six intracellular enzymes. The study revealed an increase with cell maturation in the specific activities of myeloperoxidase, NADPH oxidase, alkaline phosphatase and acid phosphatase in normal animals; in stimulated animals only myeloperoxidase and NADPH oxidase increased significantly with cell maturation. Glucose-6-phosphate dehydrogenase showed no change in specific activity in all animals studied. Malate dehydrogenase tended to show a specific activity decrease in the maturing cells of normal but not in those of stimulated animals.
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PMID:Characterization of marrow granulocyte development: enzyme-specific activity profiles in response to inflammatory reactions. 2 66


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