Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effects of inhibitors and activators on the azo- and nitro-reductases of Ascaris lumbricoides var suum have been investigated. Both types of reduction were inhibited by FAD, FMN, riboflavin, allopurinol, dicoumarol, 5-nitro-2-furaldehyde, azide and cyanide at concentrations of 1 mM. Neither reaction was inhibited by menadione, nitrofurantoin, SKF 525-A or fluoride. Both reactions were stimulated by addition of hypoxanthine. 2. The enzyme preparation contained no detectable aldehyde oxidase or xanthine oxidase activity. 3. The differences in the effects of flavins and inhibitors on mammalian and nematode azo- and nitro-reductases might have practical significance in the development of anthelmintic synergists.
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PMID:The effect of flavins and enzyme inhibitors on 4-nitrobenzoic acid reductase and azo reductase of Ascaris lumbricoides var suum. 5 46

NADPH-dependent flavin reductase (required for the activation of chorismate synthase) was purified to homogeneity from cell-free extracts of Bacillus subtilis. The enzyme has a molecular weight of 13,000 as determined by sodium dodecyl sulfate-gel electrophoresis, is specific for NADPH, and requires a divalent metal ion and either FMN or FAD for maximal rates of NADPH oxidation. The enzyme is able to reduce 2,6-dichlorophenolindophenol (DCIP) in the presence of NADPH and a divalent metal ion. Both catalytic activities were completely inhibited by EDTA. The Km for FMN is 1.25 X 10(-5) M and for NADPH 7.8 X 10(-5) M with oxygen as the final electron acceptor, and 3.85 X 10(-4) M with DCIP as the final electron acceptor. The enzyme was also isolated in association with chorismate synthase and dehydroquinate synthase. The enzyme associated with the complex has the same catalytic properties as the dissociated enzyme except that it requires both a divalent metal ion and FMN for DCIP reduction. Maximal enzyme activity was observed when the enzyme was preincubated with FMN and the divalent metal ion. The enzyme complex is easily dissociable and the dissociation of the enzyme complex resulted in the failure of NADPH-dependent flavin reductase to adsorb to phosphocellulose.
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PMID:Purification and characterization of NADPH-dependent flavin reductase. An enzyme required for the activation of chorismate synthase in Bacillus subtilis. 9 84

Chorismatic synthase was purified to apparent homogeneity from Bacillus subtilis. The enzyme required NADPH-dependent flavin reductase, Mg2+, NADPH, and flavin (FMN or FAD) for activity. The molecular weight of chorismate synthase was 24,000 as determined by sodium dedecyl sulfate (SDS)-gel electrophoresis. The enzyme was also isolated in a complex form associated with NADPH-dependent flavin reductase and another enzyme of the aromatic amino acid pathway, dehydroquinate synthase. On SDS-gel electrophoresis, this form was resolved into three bands with molecular weights of 13,000, 17,000, and 24,000. The enzyme complex was easily dissociated and the dissociation resulted in a change in the chromatographic properties of NADPH-dependent flavin reductase which was no longer retained on phosphocellulose whereas chorismate synthase was still adsorbed. Chorismate synthase activity was linear with time and protein concentration, whereas partially purified preparations showed a significant lag period before the reaction took place. Moreover, crude or partially purified enzyme preparations were completely inactivated by dilution and the activity could be recovered by addition of flavin reductase. A possible role of NADPH-dependent flavin reductase in the activation and regulation of chorismate synthase activity is discussed.
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PMID:Purification and properties of chorismate synthase from Bacillus subtilis. 9 85

NADPH-cytochrome c (P-450) reductase (EC 1.6.2.4) was purified to apparent homogeneity from microsomes of house flies, Musca domestica L. The purification procedure involves column chromatography on three different resins. The key step in the purification scheme is the chromatography of the enzyme mixture on an affinity column of agarose-hexane-nicotinamide adenine dinucleotide phosphate. The enzyme has an estimated molecular weight of 83,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and contains 1 mol each of FAD and FMN per mol of enzyme. The enzyme exhibited a Bi Bi ping-pong kinetic mechanism with NADPH and cytochrome c. The Vmax and Km for cytochrome c were 42.3 mumol min-1 mg-1 and 12.7 muM, respectively. Turnover numbers based on micromoles of enzyme were 2,600 min-1. NADP+ and 2'-AMP both inhibited the reductases with apparent Ki values of 6.9 and 187 muM, respectively. These preparations of NADPH-cytochrome c reductase were found to reduce purified house fly cytochrome P-450 in the presence of NADPH.
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PMID:Preparation of homogenous NADPH cytochrome c (P-450) reductase from house flies using affinity chromatography techniques. 10 96

An azoreductase has been purified to apparent homogeneity from the hepatic 105,000 x g supernatant fraction of 3-methylcholanthrene-treated rats. In the presence of sodium dodecyl sulfate, the purified enzyme preparation electrophoreses on polyacrylamide gels as a single protein band with a molecular weight of 30,000. In the absence of detergent, chromatography of the azoreductase on Sephadex G-100 gives a molecular weight of about 52,000 suggesting that the native enzyme may exist as a dimer. The purified azoreductase has a typical flavoprotein absorption spectrum and contains 2 mol of FAD/mol of enzyme. The enzyme catalyzes the reductive fission of methyl red (2'-carboxy-4-N,N-dimethylaminoazobenzene) and a structure-activity study indicates that the 2'-carboxyl group of methyl red is essential for catalysis since other structurally related analogs are totally inactive.
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PMID:Rat liver cytosolic azoreductase. Purification and characterization. 10 65

Riboflavine uptake and membrane-associated riboflavin-binding activity has been investigated in Bacillus subtilis. Riboflavin uptake proceeds via a system whose general properties are indicative of a carrier-mediated process: it is inhibited by substrate analogues, exhibits saturation kinetics, and is temperature-dependent. The organism concentrates riboflavin primarily as the phosphorylated cofactors FMN and FAD. Energy is required for uptake but whether the energy demand is required for both uptake and phosphorylation or only for the phosphorylation step is not known. Membrane-associated binding activity for riboflavin has also been demonstrated in membrane vesicles prepared from B. subtilis, and the binding component can be "solubilized" with Triton X-100. Evidence supporting the function of the binding component in riboflavin uptake by the intact cells includes the following. (i) Riboflavin analogues inhibit binding and uptake to nearly the same extent and with similar specificity of action. (ii) The KD for riboflavin-binding and the Km for uptake are in the same range. Similarly the Ki determined for the inhibitory analogue 5-deazariboflavin in the uptake assay and the KD for its interaction with the riboflavin-binding component of membrane vesicles are in the same range. (iii) Uptake in cells and binding in vesicles vary in the same direction with differences in growth conditions.
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PMID:Transport and binding of riboflavin by Bacillus subtilis. 11 Aug 6

1. NADPH-cytochrome c reductase was solubilized with bromelain and purified about 400-fold from sucrose/pyrophosphate-washed microsomal fractions from southern armyworm (Spodoptera eridania) larval midguts. 2. The enzyme has a mol.wt. of 70 035 +/- 1300 and contained 2 mol of flavin/mol of enzyme consisting of almost equimolar amounts of FMN and FAD. 3. Aerobic titration of the enzyme with NADPH caused the formation of a stable half-reduced state at 0.5 mol of NADPH/mol of flavin. 4. Kinetic analysis showed that the reduction of cytochrome c proceeded by a Bi Bi Ping Pong mechanism. 5. Apparent Km values for NADPH and cytochrome c and Ki values for NADP+ and 2'-AMP were considerably higher for the insect reductase than for the mammalian liver enzyme. 6. These are discussed in relation to possible differences in the active sites of the enzymes.
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PMID:Purification and characterization of NADPH--cytochrome c reductase from the midgut of the southern armyworm (Spodoptera eridania). 11 98

1. Alcohol oxidase (alcohol:oxygen oxidoreductase) was purified 22-fold from the brown rot fungus Poria contigua. The final enzyme preparation was homogeneous as judged by polyacrylamide gel electrophoresis, and by sedimentation in an ultracentrifuge. The molecular weight was calculated to be 610000 +/- 5000 from sedimentation equilibrium experiments. Electrophoresis in sodium dodecylsulfate gels and electron microscopic analysis indicate that the enzyme is an octamer composed of eight probably identical subunits, each having a molecular weight of 79 000. The enzyme contains eight mol FAD/mol as the prosthetic group. 2. This alcohol oxidase oxidizes not only methanol but also lower primary alcohols (C2-C4), 2-propin-1-ol and formaldehyde. The apparent Km value for methanol is 0.2 mM, and that for formaldehyde 6.1 mM. Sodium azide was found to be a competitive inhibitor with respect to methanol. 3. The enzyme from the fungus Poria contigua is immunologically different from the alcohol oxidase isolated from the methanol-utilizing yeast Candida boidinii. Furthermore antiserum raised against this enzyme did not cross-react with the alcohol oxidase from the white rot fungus Polyporus obtusus.
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PMID:Purification and properties of alcohol oxidase from Poria contigua. 11 5

Adrenocortical NADPH-cytochrome P-450 reductase (EC. 1.6.2.4) was purified from bovine adrenocortical microsomes by detergent solubilization and affinity chromatography. The purified cytochrome P-450 reductase was a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, being electrophoretically homogeneous and pure. The cytochrome P-450 reductase was optically a typical flavoprotein. The absorption peaks were at 274, 380 and 45 nm with shoulders at 290, 360 and 480 nm. The NADPH-cytochrome P-450 reductase was capable of reconstituting the 21-hydroxylase activity of 17 alpha-hydroxyprogesterone in the presence of cytochrome P-45021 of adrenocortical microsomes. The specific activity of the 21-hydroxylase of 17 alpha-hydroxyprogesterone in the reconstituted system using the excess concentration of the cytochrome P-450 reductase, was 15.8 nmol/min per nmol of cytochrome P-45021 at 37 degrees C. The NADPH-cytochrome P-450 reductase, like hepatic microsomal NADPH-cytochrome P-450 reductase, could directly reduce the cytochrome P-45021. The physicochemical properties of the NADPH-cytochrome P-450 reductase were investigated. Its molecular weight was estimated to be 80 000 +/- 1000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analytical ultracentrifugation. The cytochrome P-450 reductase contained 1 mol each FAD and FMN as coenzymes. Iron, manganese, molybdenum and copper were not detected. The Km values of NADPH and NADH for the NADPH-cytochrome c reductase activity and those of cytochrome c for the activity of NADPH-cytochrome P-450 reductase were determined kinetically. They were 5.3 microM for NADPH, 1.1 mM for NADH, and 9-24 microM for cytochrome c. Chemical modification of the amino acid residues showed that a histidyl and cysteinyl residue are essential for the binding site of NADPH of NADPH-cytochrome P-450 reductase.
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PMID:Physicochemical properties of reduced nicotinamide adenine dinucleotide phosphate-cytochrome P-450 reductase from bovine adrenocortical microsomes. 12 Oct 57

The properties of electron transport systems present in soluble and particulate fractions of spores of Bacillus megaterium KM?HAVE BEEN COMPARED WIth those of similar fractions prepared from exponential-phase vegetative cells of this organism. The timing and localization of modifications of the electron transport system occurring during sporulation have been investigated by using a system for separating forespores from mother cells at all stages during development [8]. Spore membranes contained cytochromes a + a3, and o at lower concentrations than in vegetative membranes, and in addition cytochrome c, which was not found in exponential-phase vegetative membranes. An NADH oxidase activity of similar specific activity was found in both spore and vegetative membranes but DL-glycerol 3-phosphate and L-malate oxidase activities were found only in vegetative membranes. A soluble NADH oxidase of low specific activity was found in spores and vegetative cells which probably involves a flavoprotein reaction with oxygen because the activity was stimulated by FAD or FMN and difference spectra of concentrated soluble fractions showed spectra typical of a flavoprotein. Particulate NADH oxidase was sensitive to all classical inhibitors of electron transport tested whereas soluble NADH oxidase was insensitive to many of these inhibitors. Cytochrome c was formed between stage I and II of sporulation and this coincided with a five-fold increase in NADH-cytochrome c reductase activity. Forespore membranes had lower contents of cytochromes than sporangial cell membranes but similar levels of NADH and L-malate oxidases; DL-glycerol 3-phosphate oxidase activity could not be detected in either membranes by stage III of sporulation. This characterization of spore electron transport systems provides a basis for suggestions concerning initial metabolic events during spore germination and the effect of a number of germination inhibitors.
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PMID:Morphogenesis of the membrane-bound electron-transport system in sporulating Bacillus megaterium KM. 12 54


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