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Query: KEGG:D02011 (FAD)
 5,530 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NAD+ reductase of the green photosynthetic bacterium Prosthecochloris aestuarii was isolated and purified by ammonium sulfate fractionation, DEAE-cellulose column chromatography, and Sephadex G-200 gel filtration. This enzyme is an FAD-containing flavoprotein and has absorption maxima at 485 (shoulder0 452, 411, and 385 nm (the 411 nm band is due to cytochrome). The molecular weight of the enzyme as determined by gel filtration using Sephadex G-200 is 119,000. The enzyme catalyzes the reduction of NAD+ and NADP+ by photoreduced spinach ferredoxin or reduced benzyl viologen...
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PMID:Isolation and some properties of NAD+ reductase of the green photosynthetic bacterium Prosthecochloris aestuarii. 0 30

Under anaerobic conditions, cells of Entamoeba histolytica grown with bacteria produce H2 and acetate while cells grown axenically produce neither. Aerobically, acetate is produced and O2 is consumed by amebae from either type of cells. Centrifuged extracts, 2.4 x 106 x g x min, from both types of cells contain pyruvate synthase (EC 1.2.7.1) and an acetate thiokinase which, together, form a system capable of converting pyruvate to acetate. Pyruvate synthase catalyzes the reaction: pyruvate + CoA leads to CO2 + acetyl-CoA + 2E. Electron acceptors which function with this enzyme are FAD, FMN, riboflavin, ferredoxin, and methyl viologen, but not NAD or NADP. The amebal acetate thiokinase catalyzes the reaction acetyl-CoA + ADP + Pi leads to acetate + ATP + CoA. For this apparently new enzyme we suggest the trivial name acetyl-CoA-synthetase (ADP-forming). Extracts from axenic amebae do not contain hydrogenase, but extracts from cells grown with bacteria do. It is postulated that in bacteria-grown amebae electrons generated at the pyruvate synthase step are utilized anaerobically to produce H2 via the hydrogenase and that the acetyl-CoA is converted to acetate in an energy-conserving step catalyzed by amebal acetyl-CoA synthetase. Aerobically, cells grown under either regimen may utilize the energy-conserving pyruvate-to-acetate pathway since O2 then serves as the ultimate electron acceptor.
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PMID:An energy-conserving pyruvate-to-acetate pathway in Entamoeba histolytica. Pyruvate synthase and a new acetate thiokinase. 1 76

Chromatography on DEAE-cellulose and gel filtration on Sephadex revealed that pyrazon dioxygenase from pyrazon-degrading bacteria consists of three different enzyme components. No component alone oxidizes the phenyl moiety of pyrazon, only when the three components are combined can oxidation be detected. Following electron paramagnetic resonance and ultraviolet measurements the protein nature of the three components was determined: component A1 (molecular weight about 180000,red-brown in colour) is an iron-sulphur protein. The existence of approximately two moles of iron and two moles of inorganic sulphur per mole of protein was demonstrated. This enzyme component was purified to homogeneity in disc electrophoresis. Component A2 is a yellow protein of a molecular weight of about 67000. FAD was shown to be the prosthetic group of this protein. Component B (molecular weight about 12000, brown in colour) is a protein of the ferredoxin type, which was purified to homogeneity, as demonstrated by disc electrophoresis. A hypothetical scheme for the cooperation of the three components is proposed: component A2 accepts as cosubstrate NADH and functions as a ferredoxin reductase. The ferredoxin, component B, has the function of an electron carrier. The conversion of the substrates is effected by component A1, the terminal dioxygenase.
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PMID:Purification and properties of pyrazon dioxygenase from pyrazon-degrading bacteria. 1 33

Pig NADPH-adrenodoxin reductase was crystallized from pig adrenocortical mitochondria and its physicochemical properties were investigated. Pig NADPH-adrenodoxin reductase is a typical flavoprotein. Its optical absorption spectrum showed peaks at 272, 377, and 450 nm in the oxidized form. The adrenodoxin reductase contained one FAD per mol. The molecular weight was 49,000. The isoelectric points of the adrenodoxin reductase and its complex with adrenodoxin were 5.3 and 4.6, respectively. Pig NADPH-adrenodoxin reductase, unlike bovine NADPH-adrenodoxin reductase, was found to be free of carbohydrate. The fluorescences of tryptophanyl residues and FAD of the adrenodoxin reductase were quenched by holo- and apo-adrenodoxins. The NADPH-binding site of the adrenodoxin reductase was examined by photooxidation and selective chemical modifications with diethyl pyrocarbonate and sulfhydryl reagents. The results indicate that a histidyl and a cysteinyl residue of the adrenodoxin reductase are essential for the NADPH-binding site. The circular dichroism spectrum of the adrenodoxin reductase showed negative ellipticity in the visible region. Spur formation was observed between pig and bovine NADPH-adrenodoxin reductases against the antibody to bovine NADPH-adrenodoxin reductase in Ouchterlony double-diffusion agar plates. The antibody did not interact with spinach ferredoxin-NADP+ reductase.
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PMID:Crystalline reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase from pig adrenocortical mitochondria. Essential histidyl and cysteinyl residues of the NADPH-binding site and environment of the adrenodoxin-binding site. 3 68

Two ferredoxin-NADP+ reductases (FNRs I and II) [EC 1.6.7.1] were purified from a blue-green alga, Spirulina platensis, by (NH4)2SO4 fractionation, gel filtration on Sephadex G-100 and DEAE-Sephadex A-50 chromatography. FNRs I and II were both FAD-containing enzymes with molecular weights of 33,000, and could photochemically reduce NADP+ to the same extent in the presence of S. platensis ferredoxin, using FNR-depleted membrane fragments of S. platensis. They had similar physical and enzymatic properties, except for chemical properties such as the amino (N)-terminal sequences and the patterns of their peptide maps. The significance of the presence of two FNRs in S. platensis as as of the multiple forms found in other organisms is discussed.
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PMID:Isolation and characterization of two ferredoxin-NADP+ reductases from Spirulina platensis. 50 May 89

NADPH-ferredoxin reductase (NADPH:ferredoxin oxidoreductase, EC 1.6.7.1) has been identified in rat liver mitochondria and purified to homogeneity as judged by sodium dodecyl sulfate (SDS) gel electrophoresis. The protein was detected by its ability to reconstitute NADPH-cytochrome c reductase in the presence of adrenal ferredoxin. The purified protein had properties very similar to adrenal NADPH-ferredoxin reductase. The molecular weight was 52 000, as estimated by gel filtration. On SDS-polyacrylamide gels, mobility was identical to that of adrenal NADPH-ferredoxin reductase (Mr = 52 000). The enzyme exhibited a typical oxidized flavoprotein absorbance spectrum with maxima at 269, 377 and 450 nm and gave an absorbance ratio A450nm/A269nm of 0.138. The fluorescence excitation spectrum was identical to that of FAD. In the presence of NADPH and a ferredoxin, the reductase was found to be active in a reconstituted cytochrome P-450-dependent steroid 26-hydroxylase, which was recently isolated from rat liver mitochondria (Pedersen, J.I. (1978) FEBS Lett. 85, 35-39).
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PMID:Purification of NADPH-ferredoxin reductase from rat liver mitochondria. 68 32

A crystalline NADPH-adrenodoxin reductase was obtained from bovine adrenocortical mitochondria and its properties were investigated. Its molecular weights and isoelectric point were estimated to be 51 000 and 5.4, respectively. Amino acid and sugar contents and the interaction between the apo-reductase and flavin of NADPH-adrenodoxin reductase were investigated. Formation of a complex of bovine NADPH-adrenodoxin reductase with adrenodoxin, its apoadrenodoxin, or other non-heme iron proteins caused quenching of fluorescence of the tryptophanyl residue and bound FAD of the NADPH-adrenodoxin reductase. The results obatined suggest that adrenodoxin and apoadrenodoxin bind functionally to a site close to the tryptophanyl residue and the bound FAD of the reductase. The circular dichroism spectrum of oxidized NADPH-adrenodoxin reductase was measured in the ultraviolet and visible regions. This spectrum showed negative absorption in the visible region and was not appreciably influenced in either the ultraviolet or visible region by formation of a complex with adrenodoxin or apoadrenodoxin.
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PMID:Properties of crystalline reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase from bovine adrenocortical mitochonria. I. Physicochemical properties of holo- and apo-NADPH-adrenodoxin reductase and interaction between non-heme iron proteins and the reductase. 98 53

NADPH-adrenodoxin reductase from steer adrenal cortex mitochrondria has been purified to homogeneity (on sodium dodecyl sulfate polyacrylamide gel electrophoresis) by chromatography on DEAE-cellulose, Sephadex, and hydroxylapatite. A molecular weight of 51,500 was determined from sodium dodecyl sulfate polyacrylamide gel electrophoresis, while sedimentation equilibrium ultracentrifugation gave a value of 49,500. All of the flavine present was identified as FAD; 1 mol/52,000 g of protein. The reductase contained 1.7% carbohydrate (using glucose as standard) by weight. Homogeneous adrenodoxin reductase exhibited a typical oxidized flavoprotein absorbance spectrum, with maxima at 270, 376, and 450 nm, and gave an absorbance ratio A450/A270 of 0.122-0.128 (depending on the preparation). Reduction of the flavoprotein with NADPH or dithionite gave progressive bleaching of the 450-nm peak. The reductase was absolutely required, in the presence of adrenodoxin, for electron transfer from NADPH to cytochrome c or to particulate cytochrome P450. Adrenodoxin refuctase is obligatory for reconstitution of 11beta-hydroxylation activity using deoxycorticosterone as substrate, and for the side-chain cleavage of 20alpha-hydroxycholesterol or cholesterol. The specific activity of the homogeneous preparation in cytochrome c reduction is at least 17,000 nmol min-1 mg of protein-1, corresponding to a turnover number of 850 min-1. No evidence for the existence of multiple forms or subunits was obtained.
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PMID:Purification and characterization of adrenodoxin reductase from bovine adrenal cortex. 112 83

The heat of reaction (deltaH) of Fe(CN)63-, Methyl Viologen, FMN and FAD with S2O42- in aqueous buffer solutions was measured calorimetrically. In addition deltaH values for reduction of Fe(CN)63-, FMN and FAD by reduced Methyl Viologen were determined. The resulting calorimetric data and corresponding E0 values were combined to yield thermodynamic data for these simple reducing agents in a form useful for applications to biological reactions. Thermodynamic data for the reduction of spinach ferredoxin are also presented.
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PMID:The thermochemical characterization of sodium dithionite, flavin mononucleotide, flavin-adenine dinucleotide and methyl and benzyl viologens as low-potential reductants for biological systems. 121 25

Oxidation-reduction titrations have been conducted to determine the midpoint potential (Em) values of the three electron-carrying prosthetic groups of the ferredoxin-linked glutamate synthase isolated from spinach leaves. Titrations using electron paramagnetic resonance (EPR) signals to monitor the oxidation state of the [3Fe-4S]+,0 cluster found in the enzyme, indicated the presence of a single n = 1 component with Em = -170 mV at pH 7.7. Titrations using absorbance changes in the visible region to monitor the oxidation states of the FAD and FMN groups present in the enzyme could be fit to a single n = 2 Nernst curve with Em = -180 mV at pH 7.7. The magnitude of the absorbance change observed during this titration accounts for all of the FMN and FAD found in the enzyme, indicating that the two flavins are either isopotential or differ in Em by less than about 30 mV. Neither optical nor EPR titrations gave any evidence for the presence of stable flavin free radicals. These results represent the first characterization of the redox properties of the prosthetic groups of a ferredoxin-dependent glutamate synthase.
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PMID:Oxidation-reduction properties of the ferredoxin-linked glutamate synthase from spinach leaf. 131 63


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