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 membrane-bound NADPH:O2 oxidoreductase of human neutrophils has been solubilized in approximately 70% yield and purified on concanavalin A-Sepharose and gel sieving columns of varying bed volumes and sieving ranges. The half-life of the solubilized oxidoreductase stored at 2-4 degrees C in the presence of 25% glycerol at pH 8.6 is approximately 30 h. The oxidoreductase contains a flavoprotein identifiable by its fluorescence spectrum for FAD which binds weakly to concanavalin A-Sepharose and elutes from gel sieving columns at a molecular weight range of approximately 51,000. This flavoprotein accounts for approximately 70% of the total FAD content found in granular membrane fractions recovered from activated neutrophils. Recovery of oxidoreductase activity from both concanavalin A-Sepharose affinity and gel sieving columns is affected by the resolution of the flavoprotein free of the cytochrome b component of the oxidoreductase. The resolved flavoprotein and cytochrome b appear unable to catalyze either NADH nor NADPH oxidase activities with O2, ferricyanide, or nitroblue tetrazolium salt serving as electron acceptors.
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PMID:Purification of the solubilized NADPH:O2 oxidoreductase of human neutrophils. Isolation of its catalytically inactive cytochrome b and flavoprotein redox centers. 335 2

Pig blood neutrophils were briefly activated by various fatty acids and then fractionated into membrane vesicles with different NADPH oxidase activities. Treatment of these membranes with a detergent, octyl glucoside, resulted in a high yield of solubilized oxidase, which was subjected to isoelectric focusing on gels (pI 4.0-8.0). 1) A distinct band staining with NADPH-nitroblue tetrazolium focused at pI 5.0. The enzyme (pI 5.0) showed high specificity for NADPH and similar characteristics to the oxidase involved in the respiratory burst. 2) The enzyme was extracted from gel slices and analyzed. When measured promptly after its extraction, its NADPH oxidase activity was high, but there was apparent superoxide dismutase-insensitive cytochrome c reduction, probably due to direct electron transfer to the heme protein. However, it could produce superoxide anion (O2-) under some micelle conditions. 3) Therefore, the formation of the enzyme-substrate complex of yeast cytochrome c peroxidase was employed for the detection of H2O2. A fresh extract of stimulated cells catalyzed equimolar NADPH oxidation and H2O2 production of 306 and 300 nmol min-1 (mg protein)-1, respectively. The Km value of the enzyme for NADPH was 30 +/- 13 (S.D.) microM. The recovery of the extract (pI 5.0) was 19% of the total activity. 4) The enzyme extract contained 1.1-1.9 nmol of FAD/mg of protein, giving a turnover number of 300-600 min-1 in terms of O2- generation/FAD. No heme protein was found in the enzyme. The enzyme was mainly of 67-kDa molecular mass.
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PMID:The respiratory burst oxidase of neutrophils. Separation of an FAD enzyme and its characterization. 362 61

The composition of NADPH oxidase purified by Red Sepharose chromatography of extracts from human neutrophil membranes was investigated. In contrast to that was recently reported by others, the enzyme isolated according to this procedure contained a high concentration of cytochrome b-245 and little FAD. The results reinforce the belief that cytochrome b-245 is a major component of the NADPH oxidase and plays a fundamental role in the formation of O2-by neutrophils.
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PMID:Presence of cytochrome b-245 in NADPH oxidase preparations from human neutrophils. 369 49

Phagocytic vesicles with superoxide-forming NADPH oxidase activity were obtained from human monocytes phagocytosing oil droplets. The superoxide-forming activity in the monocyte vesicles increased for the first 5 min during incubation with oil droplets and remained constant for 30 min. NADPH-dependent activities of 2,6-dichlorophenol-indophenol (DCIP) reduction and ubiquinone-1 (Q1) reduction were found in the vesicles and the activities were closely associated with the superoxide-forming oxidase. The values of apparent Km for NADPH of these three activities were essentially the same and the activities were inhibited with a similar pattern by p-chloromercuribenzoate and a cationic detergent, cetyltrimethylammonium bromide. The activities were extremely labile and the DCIP reductase activity was most labile. The superoxide-forming oxidase and the Q1 reductase could be extracted with a mixture of deoxycholate and Tween-20. The extracted activities were not enhanced by the addition of FAD.
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PMID:NADPH-dependent superoxide-forming oxidase in phagocytic vesicles of human monocytes. 374 37

Chronic granulomatous disease (CGD), an immunodeficiency syndrome characterized by extreme susceptibility to bacterial infections, is due to a defect of the respiratory burst in human phagocytes. NADPH oxidase, the enzyme that catalyzes the reduction of oxygen and the release of oxidative radicals, was studied in polymorphonuclear leucocytes (PMNs) in a family affected by an x-linked inheritance form at high penetrance of the disease. The contents of cytochrome b, suggested as the terminal component of the oxidase electron transport chain, and FAD, the hypothetical proximal component of the chain, were determined in patients and in carriers. Cytochrome b showed the typical behaviour of x-linked CGD: total absence in patients, intermediate values in carriers. FAD content evaluated on plasma membranes was less decreased than cytochrome b. Carriers also showed a decrease of this flavoprotein. Cytochrome b and FAD contents were compared to NBT test and superoxide production: a clear correlation was observed for the cytochrome b, but FAD plasma membrane evaluation could also be an interesting tool for the metabolic characterization of the disease in patients and in carriers.
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PMID:Cytochrome b and FAD content in polymorphonuclear leucocytes in a family with X-linked chronic granulomatous disease. 378 83

An NADH cytochrome c reductase has been identified in plasma membrane fractions from neutrophils in addition to the superoxide producing NADPH oxidase which has been extensively studied by other investigators. Activation of neutrophils resulted in increased enzyme activities but to different degrees; the NADH cytochrome c reductase increased 2 fold in specific activity and the NADPH oxidase 30 fold. Treatment of the plasma membrane fraction with sonication and differential centrifugation yielded a particulate fraction (R2) with a 2 fold increase in specific activities of both enzymes and concentrations of cytochrome b and FAD. The cytochrome b in the preparation was not reduced under anaerobic conditions by either NADH or NADPH. Treatment of preparations of R2 with deoxycholate or potassium thiocyanate separated the two enzymes yielding particulate preparations with only NADPH oxidase or NADH cytochrome c reductase activity, respectively.
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PMID:Studies of pyridine nucleotide oxidizing enzymes from human neutrophils. 393 11

NADPH oxidase activity was solubilized by detergent treatment of subcellular particles obtained from guinea-pig peritoneal macrophages stimulated with phorbol myristate acetate. Gel filtration of the material containing the NADPH oxidase activity gave two peaks of proteins, one of which eluted with the void and the other with the included volume of an AcA 22 column. The material eluted in the void volume contained more than 50% of the NADPH oxidase activity and less than 10% of the NAD(P)H cytochrome c reductase activity. A b-type cytochrome with peaks of absorption at 558, 528 and 426 nm was also enriched in the fraction which contained the NADPH oxidase activity. The distribution of flavoproteins as revealed by the measurement of FAD was different from that of NADPH oxidase and cytochrome b, and followed the elution profile of NADH cytochrome c reductase. Studies in subcellular particles showed that the b cytochromes of mitochondria and endoplasmic reticulum reduced by selective biochemical means accounted for only a minor part of the total b-type cytochromes and that the new cytochrome b previously described in neutrophils is the major chromophore also in macrophages. Oxidation-reduction midpoint potential of the partially purified cytochrome b was shown to be -247 mV. Association of cytochrome b with the NADPH oxidase activity and its very low Em7.0 makes it a suitable candidate to be part of the superoxide-generating system also in macrophages.
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PMID:Partial purification of the superoxide-generating system of macrophages. Possible association of the NADPH oxidase activity with a low-potential (-247 mV) cytochrome b. 406 52

A membrane-bound NADPH-cytochrome c reductase, which is capable of forming the superoxide anion (O2-) in the presence of menadione, was highly purified from membrane fractions of disrupted guinea pig polymorphonuclear leukocytes by solubilization with 0.2% Triton X-100 and chromatographies on Sephacryl S-300 and 2',5'-ADP-agarose. The overall purification from the membrane fraction was over 110-fold, with a yield of about 6%. The purified preparation did not contain two other pyridine nucleotide-oxidizing enzymes: NADH- and NAD(P)H-oxidizing enzymes (J. Biochem. 94, 931-936, 1983). Besides cytochrome c, the purified enzyme was able to reduce menadione, Nitroblue tetrazolium (NBT) and 2,6-dichlorophenolindophenol. The reduction of menadione alone resulted in the formation of O2-. The purified enzyme preparation contained FAD. When assayed by measuring O2--generation in the presence of menadione, the enzyme showed an optimum pH at 7.0-7.4, and Km values for NADPH, NADH, and menadione were 25, 230, and 5.3 microM, respectively. The enzyme activity was not inhibited by NaN3 or dicumarol, but was by N-ethylmaleimide, EDTA, and quercetin; these inhibition profiles agree with those observed for the NADPH oxidase in the membrane fraction of phorbol-myristate acetate-stimulated leukocytes. Furthermore, when compared by means of the NBT-staining method combined with disc gel electrophoresis, the purified enzyme was electrophoretically indistinguishable from the NADPH-NBT reductase in the plasma membrane as well as phagosomes of the leukocytes. These results suggest that the purified NADPH-cytochrome c reductase is the putative flavoprotein of the NADPH oxidase system responsible for the respiratory burst.
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PMID:Purification and characterization of a membrane-bound NADPH-cytochrome c reductase capable of catalyzing menadione-dependent O2- formation in guinea pig polymorphonuclear leukocytes. 609 21

The superoxide (O2.-)-forming enzyme NADPH oxidase from pig neutrophils was solubilized and partially purified by gel-filtration chromatography. The purification procedure allowed the separation of NADPH oxidase activity from NADH-dependent cytochrome c reductase and 2,6-dichlorophenol-indophenol reductase activities. O2.-forming activity was co-purified with cytochrome b-245 and was associated with phospholipids. However, active fractions endowed with cytochrome b were devoid of ubiquinone and contained only little FAD. The cytochrome b/FAD ratio was 1.13:1 in the crude solubilized extract and increased to 18.95:1 in the partially purified preparations. Most of FAD was associated with fractions containing NADH-dependent oxidoreductases. These results are consistent with the postulated role of cytochrome b in O2.-formation by neutrophil NADPH oxidase, but raise doubts about the participation of flavoproteins in this enzyme activity.
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PMID:Composition of partially purified NADPH oxidase from pig neutrophils. 643 85

Human neutrophils were fractionated by nitrogen cavitation and Percoll density centrifugation, and the subcellular localization of FAD-flavoprotein, b-cytochrome, NADH-cytochrome b5 reductase, and NADPH-dependent cytochrome c reductase were determined in normal cells, cells from two patients with chronic granulomatous disease (CGD), and normal cells that had been stimulated with phorbol myristate acetate. In normal cells, a FAD-flavoprotein is found in a 1:2 molar ratio, with cytochrome b in the fractions containing the specific granules. Triton X-114 phase distribution indicates that the b-cytochrome but not the b-cytochrome-associated flavoprotein is an integral membrane protein. 80% of this flavoprotein, as well as all the b-cytochrome, was absent in these fractions from 2 CGD patients, although these patients had normal quantities of FAD in the fractions containing plasma membranes and cytosol. During stimulation the b-cytochrome-associated flavoprotein of the granules translocates with the b-cytochrome to the plasma membrane where NADPH oxidase is localized. Definition of the role of these NADPH oxidase constituents may provide a molecular description of the normal neutrophil respiratory burst and the molecular defect(s) in CGD.
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PMID:Subcellular localization of the human neutrophil NADPH oxidase. b-Cytochrome and associated flavoprotein. 670 48


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