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)

A particulate fraction prepared from Mycobacterium phlei grown in a metal-deficient medium exhibited a greatly reduced activity of stearoyl-CoA desaturase compared to that from normally grown cells. Metal deficiency, however, had no effect on the FAD-dependent NADPH-cytochrome C reductase activity, which has been suggested to participate in the desaturation process. When the cells were grown in the deficient medium supplemented with both Fe2+ and Mg2+, the desaturase activity was restored to the normal level. Supplementation with Mg2+ alone promoted growth but did not restore the desaturase activity, whereas Fe2+ alone did cause a significant restoration. Among the various metal ions tested, only Fe2+ and Fe3+ enhanced the formation of desaturase activity in the deficient medium. When added to the assay medium in vitro, Fe2+ and Fe3+ did not stimulate the desaturase activity of the particulate fraction from the deficient cells. Cultivation in the metal-deficient medium had essentially no effect on the levels of cytochromes in the particulate fraction, but dramatically decreased the non-heme iron content and the amount of a high-spin ferric species exhibiting an ESR signal at g=4.3. No labile sulfur could be detected in the normal or metal-deficient particulate fractions. It is concluded that the presence of iron ions in the culture medium is necessary for the synthesis and/or assembly of the terminal portion of the desaturase system.
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PMID:Effect of metal ions in the culture medium on the stearoyl-coenzyme A desaturase activity of Mycobacterium phlei. 0 87

2-Nitropropane dioxygenase, purified to homogeneity from Hansenula mrakii (IFO 0895), has a molecular weight of approximately 62,000 and consists of two subunits nonidentical in molecular weight (39,000 and 25,000). Stoichiometrical studies and the results obtained with 18O2 showed that 2 atoms of molecular oxygen are incorporated into 2 molecules of acetone formed from 2-nitropropane. In addition to 2-nitropropane, nitroethane, 3-nitro-2-pentanol, and 1-nitropropane are oxidatively dentrified. The enzyme, which exhibits absorption maxima at 274, 370, 415, and 440 nm and a shoulder at 470 nm, contains 1 mol of FAD and 1 g atom of non-heme iron per mol of enzyme. The enzyme-bound FAD is reduced by 2-nitropropane under anaerogic conditions, but the enzyme-bound Fe3+ is not affected. The introduction of oxygen to the reduced form of enzyme causes reoxidation of the enzyme. The bound FAD and Fe3+ are reduced by the addition of nitromethane, which is not a substrate, under anaerobic conditions. The aerobic dialysis of the enzyme treated with nitromethane causes reoxidation of only the Fe2+. Sodium dithionite also reduces both the enzyme-bound FAD and Fe3+ under anaerobic conditions. When the enzyme is dialyzed against 10 mM potassium phosphate buffer (pH 7.0) immediately after reduction by dithionite, the absorption spectrum similar to that of the native enzyme appeared with concomitant restoration of approximately 80% of the activity. The enzyme activity is significantly inhibited by pyrocatechol-3,5-disulfonate disodium salt, 8-hydroxyquinoline, reducing agents such as 2-mercaptoethanol, and HgCl2. The Michaelis constants are as follows: 2-nitropropane (2.13 X 10(-2) M), nitroethane (2.43 X 10(-2) M), 3-nitro-2-pentanol (6.8 X 10(-3) M), 1-nitropropane (2.56 X 10(-2) M), and oxygen (3.03 X 10(-4) M, with 2-nitropropane).
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PMID:A new oxygenase, 2-nitropropane dioxygenase of Hansenula mrakii. Enzymologic and spectrophotometric properties. 1 Dec 14

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

The formation of aminoacids and proteins from the nitrogen which enters the roots as nitra t involves a complex reaction requiring energy. The first step requires a metalloflavoprotein, the nitrate reductase and the successive intervention of NADPH, FAD and reduced molybdenum which transfers electrons to nitrate and reduces it to nitrite. The following steps involve NADPH, FAD, Copper, Iron and Manganese, the last steps of the successive reductions being ammonia, needed for the aminoacids synthesis. The activity of the different enzymes are under the dependence of the genetic equipment of the plant, of the nitrogen and oligo-element nutrition and of the different factors acting on the photosynthesis.
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PMID:[Nitrates and nitrites in plants]. 2 19

Neurospora crassa wild type STA4 NADPH-nitrate reductase (NADPH : nitrate oxidoreductase, EC 1.6.6.3) has been purified 5000-fold with an overall yield of 25--50%. The final purified enzyme contained 4 associated enzymatic activities: NADPH-nitrate reductase, FADH2-nitrate reductase, reduced methyl viologen-nitrate reductase and NADPH-cytochrome c reductase. Polyacrylamide gel electrophoresis yielded 1 major and 1 minor protein band and both bands exhibited NADPH-nitrate and reduced methyl viologen-nitrate reductase activities. SDS gel electrophoresis yielded 2 protein bands corresponding to molecular weights of 115 000 and 130 000. A single N-terminal amino acid (glutamic acid) was found and proteolytic mapping for the two separated subunits appeared similar. Purified NADPH-nitrate reductase contained 1 mol of molybdenum and 2 mol of cytochrome b557 per mol protein. Non-heme iron, zinc and copper were not detectable. It is proposed that the Neurospora assimilatory NADPH-nitrate reductase consists of 2 similar cytochrome b557-containing 4.5-S subunits linked together by one molybdenum cofactor. A revised electron flow scheme is presented. p-Hydroxymercuribenzoate inhibition was reversed by sulfhydryl reagents. Inhibitory pattern of p-hydroxymercuribenzoate and phenylglyoxal revealed accessible sulfhydryl and arginyl residue(s) as functional group(s) in the earlier part of electron transport chain as possibly the binding site of NADPH or FAD.
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PMID:Purification and characterization of homogeneous assimilatory reduced nicotinamide adenine dinucleotide phosphate-nitrate reductase from Neurospora crassa. 2 8

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 Neurospora crassa assimilatory nitrite reductase (EC 1.6.6.4) catalyzes the NADPH-dependent reduction of nitrite to ammonia, a 6-electron transfer reaction. Highly purified preparations of this enzyme exhibit absorption spectra which suggest the presence of a heme component (wavelength maxima for oxidized senzyme: 390 and 578 nm). There is a close correspondence between nitrite reductase activity and absorbance at 400 nm when partially purified nitrite reductase preparations are subjected to sucrose gradient centrifugation. In addition, a role for an iron component in the formation of active nitrite reductase is indicated by the fact that nitrate-induced production of nitrite reductase activity in Neurospora mycelia in vivo requires the presence of iron in the induction medium. The heme chromophore present in Neurospora nitrite reductase preparations is reducible by NADPH. Complete reduction, however, requires the presence of added FAD. The NADPH-nitrite reductase activity of the enzyme is also dependent upon addition of FAD. A spectrally unique complex is formed between the heme chromophore and nitrite (or a reduction product thereof) when nitrite is added to NADPH-reducted enzyme. Carbon monoxide forms a complex with the heme chromophore of nitrite reductase with an intense alpha-band maximum at 590 nm and a beta-band of lower intensity at 550 nm. CO is an inhibitor of NADPH-nitrite reductase activity. Spectrophotometrically detectable CO complex formation and Co inhibition of enzyme activity share the following properties...
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PMID:Siroheme: a prosthetic group of the Neurospora crassa assimilatory nitrite reductase. 12 95

Xanthine dehydrogenase (EC 1.2.1.37) is the first enzyme in the degradative pathway by which fungi convert purines to ammonia. In vivo, the activity is induced 6-fold by growth in uric acid. Hypoxanthine, xanthine, adenine, or guanine also induce enzyme activity but to a lesser degree. Immunoelectrophoresis using monospecific antibodies prepared against Neurospora crassa xanthine dehydrogenase shows that the induced increase in enzyme activity results from increased numbers of xanthine dehydrogenase molecules, presumably arising from de novo enzyme synthesis. Xanthine dehydrogenase has been purified to homogeneity by conventional methods followed by immunoabsorption to monospecific antibodies coupled to Sepharose 6B. Electrophoresis of purified xanthine dehydrogenase reveals a single protein band which also exhibits enzyme activity. The average specific activity of purified enzyme is 140 nmol of isoxanthopterine produced/min/mg. Xanthine dehydrogenase activity is substrate-inhibited by xanthine (0.14 mM), hypoxanthine (0.3 mM), and pterine (10 micron), is only slightly affected by metal binding agents such as KCN (6 mM), but is strongly inhibited by sulfhydryl reagents such as p-hydroxymercuribenzoate (2 micron). The molecular weight of xanthine dehydrogenase is 357,000 as calculated from a sedimentation coefficient of 11.8 S and a Stokes radius of 6.37 nm. Sodium dodecyl sulfate-gel electrophoresis of the enzyme reveals a single protein band having a molecular weight of 155,000. So the xanthine dehydrogenase protein appears to be a dimer. In contrast to xanthine dehydrogenases from animal sources which typically possess as prosthetic groups 2 FAD molecules, 2 molybdenum atoms, 8 atoms of iron, and 8 acid-labile sulfides, the Neurospora enzyme contains 2 FAD molecules, 1 molybdenum atom, 12 atoms of iron, and 14 eq of labile sulfide/molecule. The absorption spectrum of the enzyme shows maxima between 400 and 500 nm typical of a non-heme iron-containing flavoprotein.
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PMID:Regulation, purification, and properties of xanthine dehydrogenase in Neurospora crassa. 14 74

F1-ATPase isolated from rat liver mitochondria has been found to contain approximately 1 mole of FAD and 6 g atoms of nonheme iron per mole of enzyme.
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PMID:Rat liver mitochondrial F1-ATPase, an FAD containing ferroprotein. 15 59

NADH:nitrate reductase (EC 1.6.6.1) from Chlorella vulgaris has been purified 640-fold with an over-all yield of 26% by a combination of protamine sulfate fractionation, ammonium sulfate fractionation, gel chromatography, density gradient centrifugation, and DEAE-chromatography. The purified enzyme is stable for more than 2 months when stored at minus 20 degrees in phosphate buffer (pH 6.9) containing 40% (v/v) glycerol. After the initial steps of the purification, a constant ratio of NADH:nitrate reductase activity to NADH:cytochrome c reductase and reduced methyl viologen:nitrate reductase activities was observed. One band of protein was detected after polyacrylamide gel electrophoresis of the purified enzyme. This band also gave a positive stain for heme, NADH dehydrogenase, and reduced methyl viologen:nitrate reductase. One band, corresponding to a molecular weight of 100, 000, was detected after sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme contains FAD, heme, and molybdenum in a 1:1:0.8 ratio. One "cyanide binding site" per molybdenum was found. No non-heme-iron or labile sulfide was detected. From a dry weight determination of the purified enzyme, a minimal molecular weight of 152, 000 per molecule of heme or FAD was calculated. An s20, w of 9.7 S for nitrate reductase was found by the use of sucrose density gradient centrifugation and a Stokes radius of 89 A was estimated by gel filtration techniques. From these values, and the assumption that the partial specific volume is 0.725 cc/g, a molecular weight of 356, 000 was estimated for the native enzyme. These data suggest that the native enzyme contains a minimum of 2 molecules each of FAD, heme, and molybdenum and is composed of at least three subunits.
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PMID:Reduced nicotinamide adenine dinucleotide-nitrate reductase of Chlorella vulgaris. Purification, prosthetic groups, and molecular properties. 16 92


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