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)

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

The soluble NADH dehydrogenase of low molecular weight, isolated from complex I (NADH:ubiquinone oxidoreductase, EC 1.6.5.3) of the respiratory chain, has been shown to have NADPH dehydrogenase and NADPH leads to NAD transhydrogenase activities. Both activities are greatly increased in the presence of added guanidine-HCl and at pH values less than 6.5. The chromophores of the soluble enzyme (flavin and iron--sulfur centers) are reduced by NADH and NADPH to the same extent. The latter reduction is extremely slow, and is considerably stimulated in the presence of guanidine-HCl. The soluble dehydrogenase has little or no NADH leads to NADP and NADPH leads to NADP transhydrogenase activity. The former reaction is known to be energy-linked in submitochondrial particles; the latter was shown in the present studies also to be energy-linked. In view of the above and earlier results, possible mechanisms for dehydrogenation and transhydrogenation (nonenergy-linked and energy-linked) involving reduced and oxidized NAD and NADP are proposed.
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PMID:Dehydrogenase and transhydrogenase properties of the soluble NADH dehydrogenase of bovine heart mitochondria. 1 55

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

1. Ethanol metabolism in slices or homogenates of transplantable hepatocellular carcinoma HC-252 (HC-252) was 50 to 60% of the rate found in host liver slices or homogenates when they were expressed per gram of tissue wet weight and 70 to 80% of the liver when the rates were expressed per milligram of tissue protein. At 10 mM ethanol, the activities of alcohol dehydrogenase in tumor and liver supernatants were comparable. 2. Tumor microsomes did not oxidize ethanol in the presence of a NADPH-generating system, indicating the absence of the microsomal ethanol-oxidizing system and catalase-mediated peroxidation of ethanol. The HC-252 microsomes were contaminated with catalase, and acetaldehyde production occurred in the presence of a H2O2-generating system (xanthine oxidase). The virtual absence of ethanol oxidation and drug metabolism (aminopyrine demethylase and aniline hydroxylase) in HC-252 microsomes may be due to the low activities of NADPH-cytochrome c reductase, NADPH oxidase, and NADPH-dependent oxygen uptake. 3. Microsomal oxidation of ethanol was present in Morris hepatoma 5123C, a well-differentiated tumor of intermediate growth rate, while activity was negligible in microsomes from Morris hepatoma 7288CTC, a less differentiated tumor. Microsomal NADPH oxidase was present in the well differentiated tumor 5123C but was lacking in the less differentiated tumor 7288CTC. Several microsomal, mitochondrial, and cytosolic properties of HC-252 are similar to those of Morris hepatoma 7288CTC but differ from those of the more differentiated 5123C tumor and normal liver. 4. The content of mitochondrial protein in HC-252 was only 25% that of liver, and oxygen consumption per gram of tumor was only 28% that of the liver. When corrected for the mitochondrial protein content, oxygen uptake in tumor HC-252 and liver homogenates was comparable. Isolated tumor and liver mitochondria displayed comparable State 4 and 3 rates of oxygen consumption with succinate and glutamate as substrates. The activities of the reconstituted malate-aspartate and alpha-glycerophosphate shuttles were only slightly lower in isolated HC-252 mitochondria compared to liver mitochondria, when shuttles were reconstituted with purified enzymes. 5. Antimycin inhibited alcohol metabolism,and pyruvate stimulated alcohol metabolism, much less in tumor slices than in liver slices, suggesting the presence of an augmented mitochondria-independent, cytosolic mechanism for oxidizing reducing equivalents in the tumor. These factors suggest that oxidation of NADH is the limiting factor in ethanol metabolism. Whereas, in the liver mitochondrial reoxidation is predominant, in HC-252, cytosolic reoxidation of NADH also plays a major role.
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PMID:Ethanol metabolism by a transplantable hepatocellular carcinoma. Role of microsomes and mitochondria. 13 37

We measured the cyanide-insensitive pyridine nucleotide oxidase activity of fractionated resting and phagocytic neutrophils from 11 normal donors, 1 patient with hereditary deficiency of myeloperoxidase, and 7 patients with X-linked chronic granulomatous disease (CGD). When measured under optimal conditions (at pH 5.5 and in the presence of 0.5 mM Mn++), NADPH oxidase activity increased fourfold with phagocytosis and was six-fold higher than with NADH. Phagocytic neutrophils from patients with CGD were markedly deficient in NADPH oxidase activity.
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PMID:NADPH oxidase deficiency in X-linked chronic granulomatous disease. 23 60

Cell-free extracts of a streptomycin-bleached strain of Euglena gracilis var. bacillaris have been examined for enzyme systems primarily responsible for the oxidation of reduced pyridine nucelotides. NADH lipoyl dehydrogenase, NADH and NADPH oxidase, NADH and NADPH diaphorase, and NADH and NADPH cytochrome c reductase have been demonstrated. The NADPH-linked enzymes had lower activity rates and were less sensitive to N-ethyl maleimide and p-hydroxymercuribenzoate than their NADH-linked counterparts. NADH cytochrome c reductase was the most sensitive to antimycin A. Michaelis-Menten constants (Km) determined were as follows: NADH diaphorase, 350 muM; NADPH oxidase 150 muM ; NADH lipoyl dehydrogenase, 0.35 muM. Enzyme activities after storage at -5 C indicate that the diaphorases are less labile than the other tested enzymes, and the differential activities of the NADH and NADPH linked enzymes suggest that functionally they may have different roles.
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PMID:Reduced pyridine nucleotide oxidases of Eugena gracilis var. bacillaris. 40 56

The actions of Dexon on the NADH-ferricyanide oxidoreductase and the NADPH oxidase system of electron transfer particles (ETP) from beef heart as well as on the NADPH-cytochrome c oxidoreductase from brewer's yeast (Saccharomyces carlsbergensis Hansen) were investigated. The inhibition of the NADH dehydrogenase activity of ETP and that of the yeast enzyme correspond with respect to the following characteristics: 1) increase in the inhibition, 2) enhancement of the Dexon sensitivity by one order of magnitude after preincubation in the presence of NAD(P)H, 3) irreversibility of the inhibition, 4) no detectable changes in the spectral properties and in coenzyme activity of FMN after acid extraction from Dexon-treated enzyme. The inhibition of the NADH dehydrogenase activity of ETP is diminished by both NAD+ and FMN. However, no interaction of Dexon with NAD(P)H or FMN could be detected in the absence of enzyme or apoenzyme. The concentration of half-inhibition by Dexon for the yeast enzyme corresponds with its FMN concentration. It is proposed that both apoenzyme, NAD(P)H and FMN are involved in the interaction with Dexon. Possible mechanisms of binding are both complanar complexations of the ring systems and a triazene formation between FMNH2 and Dexon. The NADPH oxidase activity of the ETP is partly inhibited; the share inhibited by Dexon may represent the pathway via the transhydrogenase reaction.
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PMID:[Mechanism of action of the inhibition of pyridine-nucleotide-dependent flavine enzymes using the systemic fungicide Dexon]. 41 38


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