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)

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

Delta5-3beta-hydroxysteroid oxidoreductase was extracted in magnesium-containing Tris buffer from sonicated Streptomyces griseocarneus cells. The enzyme was partially purified (150 X) by ion exchange chromatography and gel filtration following (NH4)2SO4 fractionation. Upon gel filtration on Sephadex G-75 to G-200, the greatest part of the activity gave a peak in the fractionation range. The enzyme obtained from the gel yielded small enzyme molecules on repeated chromatography. A molecular weight of 32 to 36 000 was calculated for the activity appearing in the fractionation range of Sephadex G-75 to G-200. The enzyme is highly specific for the irreversible oxidation of the 3beta-hydroxyl group in steroids with a trans-anellated A : B ring system with either C5 or C6 double bond. Delta5-3-ketosteroids are converted into delta5-3-ketosteroids at a high rate, but the isomerase activity cannot be separated from the oxidoreductase activity either by chromatography or by selective heat inactivation. NAD, NADP, FMN or FAD did not influence the activity, but the enzyme is inactive in the absence of molecular oxygen.
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PMID:Properties of delta5-3beta-hydroxysteroid oxidoreductase isolated from Streptomyces griseocarneus. 0 56

Various flavins, FMN, FAD, and acriflavin, were immobilized to Sepharose using several different coupling methods. The only product stable enough to permit extended studies was acriflavin coupled to epoxy-substituted Sepharose. The nonenzymic oxidizing capacity towards NAD(P) H was investigated and a 25% specific activity, compared to that of free acriflavin, was observed. The reduced acriflavin was immediately auto-reoxidized in air and could thus be reused. It was shown that acriflavin-Sepharose preparations function as NAD(P)H oxidizing agents in a number of different dehydrogenase systems including lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), malate dehydrogenase (MDH), alanine dehydrogenase (alaDH), and glutamate dehydrogenase (GDH). The amount of expensive coenzyme necessary for high product formation of such systems was thereby markedly reduced.
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PMID:Continuous regeneration of NAD(P)+ by flavins covalently bound to sepharose. 0 69

The assimilatory NADPH-nitrate reductase (NADPH:nitrate oxidoreductase, EC 1.6.6.3) from Neurospora crassa is competitively inhibited by 3-aminopyridine adenine dinucleotide (AAD) and 3-aminopyridine adenine dinucleotide phosphate (AADP) which are structural analogs of NAD and NADP, respectively. The amino group of the pyridine ring of AAD(P) can react with nitrous acid to yield the diazonium derivative which may covalently bind at the NAD(P) site. As a result of covalent attachment, diazotized AAD(P) causes time-dependent irreversible inactivation of nitrate reductase. However, only the NADPH-dependent activities of the nitrate reductase, i.e. the overall NADPH-nitrate reductase and the NADPH-cytochrome c reductase activities, are inactivated. The reduced methyl viologen- and reduced FAD-nitrate reductase activities which do not utilize NADPH are not inhibited. This inactivation by diazotized AADP is prevented by 1 mM NADP. The inclusion of 1 muM FAD can also prevent inactivation, but the FAD effect differs from the NADP protection in that even after removal of the exogenous FAD by extensive dialysis or Sephadex G-25 filtration chromatography, the enzyme is still protected against inactivation. The FAD-generated protected form of nitrate reductase could again be inactivated if the enzyme was treated with NADPH, dialyzed to remove the NADPH, and then exposed to diazotized AADP. When NADP was substituted for NADPH in this experiment, the enzyme remained in the FAD-protected state. Difference spectra of the inactivated nitrate reductase demonstrated the presence of bound AADP, and titration of the sulfhydryl groups of the inactivated enzyme revealed that a loss of accessible sulfhydryls had occurred. The hypothesis generated by these experiments is that diazotized AADP binds at the NADPH site on nitrate reductase and reacts with a functional sulfhydryl at the site. FAD protects the enzyme against inactivation by modifying the sulfhydryl. Since NADPH reverses this protection, it appears the modifications occurring are oxidation-reduction reactions. On the basis of these results, the physiological electron flow in the nitrate reductase is postulated to be from NADPH via sulfhydryls to FAD and then the remainder of the electron carriers as follows: NADPH leads to -SH leads to FAD leads to cytochrome b-557 leads to Mo leads to NO-3.
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PMID:Reactions of the Neurospora crassa nitrate reductase with NAD(P) analogs. 1 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

The three-dimensional structure of the dimeric flavoenzyme glutathione reductase from human erythrocytes has been elucidated by an X-ray diffraction analysis at 0.3 nm resolution. The polypeptide chain has been traced, and the binding positions of FAD, NADP and glutathione have been determined. A mechanism for the electron transfer is discussed.
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PMID:The structure of the flavoenzyme glutathione reductase. 2 87

Glutathione reductase (NAD(P)h:oxidized glutathione oxidoreductase, EC 1.6.4.2) has been purified 1000-fold from the cytoplasmic fraction of human platelets. Salts, including the heretofore unreported effect of sodium citrate, activate the NADPH-dependent reduction of oxidized glutathione. Sodium citrate and monovalent salt activation appears to involve multiple sites having different binding affinities. At sub-saturating sodium phosphate, non-linear double reciprocal plots indicative of substrate activation by oxidized glutathione were observed. Initial velocity double reciprocal plots at sub-saturating and saturating concentrations of phosphate generate a family of converging lines. NADP+ is a partial inhibitor, indicating that the reduction of oxidized glutathione can proceed by more than one pathway. FMN, FAD, and riboflavin inhibit platelet glutathione reductase by influencing only the V while nitrofurantoin inhibition is associated with an increase Koxidized glutathione and a decreased V.
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PMID:Characterization of human platelet glutathione reductase. 3 11

Glutathione reductase from the liver of DBA/2J mice was purified to homogeneity by means of ammonium sulfate fractionation and two subsequent affinity chromatography steps using 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose and N6-(6-aminohexyl)-adenosine 2',5'-biphosphate-Sephadex columns. A facile procedure for the synthesis of 8-(6-aminohexyl)-amino-2'-phospho-adenosine diphosphoribose is also presented. The purified enzyme exhibits a specific activity of 158 U/mg and an A280/A460 of 6.8. It was shown to be a dimer of Mr 105000 with a Stokes radius of 4.18 nm and an isoelectric point of 6.46. Amino acid composition revealed some similarity between the mouse and the human enzyme. Antibodies against mouse glutathione reductase were raised in rabbits and exhibited high specificity. The catalytic properties of mouse liver glutathione reductase have been studied under a variety of experimental conditions. As with the same enzyme from other sources, the kinetic data are consistent with a 'branched' mechanism. The enzyme was stabilized against thermal inactivation at 80 degrees C by GSSG and less markedly by NADP+ and GSH, but not by NADPH or FAD. Incubation of mouse glutathione reductase in the presence of NADPH or NADH, but not NADP+ or NAD+, produced an almost complete inactivation. The inactivation by NADPH was time, pH and concentration dependent. Oxidized glutathione protected the enzyme against inactivation, which could also be reversed by GSSG or other electron acceptors. The enzyme remained in the inactive state even after eliminating the excess NADPH. The inactive enzyme showed the same molecular weight as the active glutathione reductase. The spectral properties of the inactive enzyme have also been studied. It is proposed that auto-inactivation of glutathione reductase by NADPH and the protection as well as reactivation by GSSG play in vivo an important regulatory role.
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PMID:Mouse-liver glutathione reductase. Purification, kinetics, and regulation. 3 57

Procedures for the purification of an aldehyde dehydrogenase from extracts of the obligate methylotroph, Methylomonas methylovora are described. The purified enzyme is homogeneous as judged from polyacrylamide gel electrophoresis. In the presence of an artificial electron acceptor (phenazine methosulfate), the purified enzyme catalyzes the oxidation of straight chain aldehydes (C1--C10 tested), aromatic aldehydes (benzaldehyde, salicylaldehyde), glyoxylate, and glyceraldehyde. Biological electron acceptors such as NAD+, NADP+, FAD, FMN, pyridoxal phosphate, and cytochrome c cannot act as electron carriers. The activity of the enzyme is inhibited by sulfhydryl agents [p-chloromercuribenzoate, N-ethylmaleimide and 5,5-dithiobis (2-nitrobenzoic acid)], cuprous chloride, and ferrour nitrate. The molecular weight of the enzyme as estimated by gel filtration is approximately 45000 and the subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 23000. The purified enzyme is light brown and has an absorption peak at 410 nm. Reduction of enzyme with sodium dithionite or aldehyde substrate resulted in the appearance of peaks at 523 nm and 552nm. These results suggest that the enzyme is a hemoprotein. There was no evidence that flavins were present as prosthetic group. The amino acid composition of the enzyme is also presented.
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PMID:Microbial oxidation of methane and methanol: purification and properties of a heme-containing aldehyde dehydrogenase from Methylomonas methylovora. 4 58

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


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