Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nicotinamide nucleotide dimers (NAD)2 and (NADP)2, obtained by electrochemical reduction of NAD+ and NADP+, are able to reduce such single-electron acceptors as the proteins cytochrome c, azurin and methaemoglobin, though at different rates. Under the same conditions the reduced nicotinamide coenzymes NADH and NADPH are not able to reduce these proteins at measurable rates unless a catalyst (phenazine methosulphate or NADH-cytochrome c reductase in the case of cytochrome) is present. The redox mechanism seems to involve the formation of an NAD(P). radical that in the presence of O2 gives rise to superoxide (O2.-), since superoxide dismutase inhibited these reactions.
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PMID:Oxidation of nicotinamide coenzyme dimers by one-electron-accepting proteins. 302 35

1. Measurements were made of the activities of the following enzymes of glycerolipid synthesis in homogenates of interscapsular brown adipose tissue obtained from rats subjected to a 4 degrees C environment for time periods of 6 h up to 12 days: fatty acyl-CoA synthetase (FAS), mitochondrial and microsomal forms of glycerolphosphate acyltransferase (GPAT), monoacylglycerolphosphate acyltransferase (MGPAT) and Mg2+-dependent phosphatidate phosphohydrolase (PPH). 2. Relative to tissue DNA content, the activities of mitochondrial GPAT, MGPAT and Mg2+-dependent PPH were significantly increased after 1 day of exposure to cold, and continued to increase thereafter. By contrast, FAS and microsomal GPAT activities were unchanged relative to tissue DNA. 3. The time profile of the increase in MGPAT activity correlated well with a concomitant increase in the microsomal marker NADP+-cytochrome c reductase. Changes in mitochondrial GPAT and in Mg2+-dependent PPH activities were larger in amplitude than that of MGPAT. 4. It is proposed that these selective changes in enzyme activity may be associated with the onset of brown-adipose-tissue hyperplasia or possibly with an increase in triacylglycerol synthesis during cold-acclimation.
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PMID:Changes in activities of some enzymes of glycerolipid synthesis in brown adipose tissue of cold-acclimated rats. 317 17

The yeast Candida parapsilosis possesses two routes of electron transfer from exogenous NAD(P)H to oxygen. Electrons are transferred either to the classical cytochrome pathway at the level of ubiquinone through an NAD(P)H dehydrogenase, or to an alternative pathway at the level of cytochrome c through another NAD(P)H dehydrogenase which is insensitive to antimycin A. Analyses of mitoplasts obtained by digitonin/osmotic shock treatment of mitochondria purified on a sucrose gradient indicated that the NADH and NADPH dehydrogenases serving the alternative route were located on the mitochondrial inner membrane. The dehydrogenases could be differentiated by their pH optima and their sensitivity to amytal, butanedione and mersalyl. No transhydrogenase activity occurred between the dehydrogenases, although NADH oxidation was inhibited by NADP+ and butanedione. Studies of the effect of NADP+ on NADH oxidation showed that the NADH:ubiquinone oxidoreductase had Michaelis-Menten kinetics and was inhibited by NADP+, whereas the alternative NADH dehydrogenase had allosteric properties (NADH is a negative effector and is displaced from its regulatory site by NAD+ or NADP+).
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PMID:The alternative respiratory pathway of the yeast Candida parapsilosis: oxidation of exogenous NAD(P)H. 326 91

Yeast glutathione reductase exists in a single molecular form which exhibits preferred NADPH and weak NADH linked multifunctional activities. Kinetic parameters for the NADPH and NADH linked reductase, transhydrogenase, electron transferase and diaphorase reactions have been determined. The functional preference for the NADPH linked reductase reaction is kinetically related to the high catalytic efficiency and low dissociation constants for substrates. NADP+ and NAD+ may interact with two different sites or different kinetic forms of the enzyme. The active site disulfide and histidine are required for the reductase activity but are not essential to the transhydrogenase, electron transferase and diaphorase activities. Amidation of carboxyl groups and Co(II) chelation of glutathione reductase facilitate the electron transferase reaction presumably by encouraging the formation of an anionic flavosemiquinone.
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PMID:Multifunctional activities of yeast glutathione reductase. 329 44

A rapid enzymatic method was developed for the assay of serum argininosuccinate lyase (ASAL: EC 4.3.2.1) which is a useful marker enzyme for diagnosis of parenchymal liver diseases. Fumarate, liberated from argininosuccinate in the lyase-mediated reaction, was converted to pyruvate via L-malate by the actions of fumarase and malic enzyme in the presence of NADP+. The NADPH formed was then oxidized with a diaphorase-resazurin system to give a highly fluorescent resorufin. All the enzymatic reactions proceeded continuously in 0.1 M Tris-HCl buffer (pH 7.5) and allowed direct assay of ASAL in serum by monitoring the increase in the fluorescence intensity due to resorufin. The method is rapid and sensitive; only 50 microliter of serum is required. This method was used to detect increases in the activities in sera from patients with liver diseases.
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PMID:An enzymatic method for the assay of serum argininosuccinate lyase. 367 95

Monospecific rabbit antibodies against the ferredoxin-NADP+ reductase binding protein of spinach thylakoids were obtained and characterized. The immunoglobulin G (IgG) fraction gave single precipitation arcs with the purified antigen or with Triton X-100 extracts of thylakoids or the reductase binding protein complex. Antibodies against the flavoprotein behave similarly. Both antibodies agglutinated thylakoids and precipitated the diaphorase activity of a Triton X-100 extract of these membranes. Isolated Fab fragments of the IgG anti-binding protein inhibited NADP+ photoreduction in a time- and Fab concentration-dependent manner. The presence of ferredoxin diminished the rate of inhibition. In the light, the inactivation rate was higher than in dark and this effect was abolished in the presence of uncouplers. These results suggest that the binding protein is protruding from the thylakoids and could be sensing the proton gradient.
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PMID:Immunological studies of the binding protein for chloroplast ferredoxin-NADP+ reductase. 381 68

The complex between ferredoxin-NADP+ oxidoreductase and its proposed membrane-binding protein (Vallejos, R. H., Ceccarelli, E., and Chan, R. (1984) J. Biol. Chem. 259, 8048-8051) was isolated from spinach thylakoids and compared with isolated cytochrome b/f complex containing associated ferredoxin NADP+ oxidoreductase (Clark, R. D., and Hind, G. (1983) J. Biol. Chem. 258, 10348-10354). There was no immunological cross-reactivity between the 17.5-kDa binding protein and an antiserum raised against the 17-kDa polypeptide of the cytochrome complex. Association of ferredoxin-NADP+ oxidoreductase with the binding protein or with the thylakoid membrane gave an allotopic shift in the pH profile of diaphorase activity, as compared to the free enzyme. This effect was not seen in enzyme associated with the cytochrome b/f complex. Identification of the 17.5-kDa binding protein as the 17-kDa component of the cytochrome b/f complex is ruled out by these results.
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PMID:The ferredoxin-NADP+ oxidoreductase-binding protein is not the 17-kDa component of the cytochrome b/f complex. 390 86

Though previously described as very low or absent in yeast, we find significant pyridine nucleotide transhydrogenation (NADPH + acetyl pyridine-NAD+----NADP+ + acetyl pyridine-NADH) activity in yeast extracts when assayed at pH 8-9, and describe here the subcellular distribution and separation of the various molecular forms contributing to the total activity in two yeast species. Gentle subcellular fractionation reveals transhydrogenase activity only in the cytosolic fraction of both Saccharomyces cerevisiae and Candida utilis while intact mitochondria and microsomes are without activity. On sucrose gradient centrifugation, this soluble cytosolic activity proves to be primarily in a high-molecular-weight (greater than 10(6)) band which has salmon-colored fluorescence on uv illumination. Sonication of the particulate subcellular fractions solubilizes substantial transhydrogenase activity from mitochondria of C. utilis (but not from S. cerevisiae) which on sucrose gradients consists of both high (greater than 10(6))- and low-molecular-weight active fractions, each with yellow-green fluorescence. Ammonium sulfate fractionation and sucrose gradient centrifugation of protein solubilized from whole yeast of both species by vigorous homogenization with glass beads confirms the presence and fluorescence of these various molecular weight forms. The relationship of these activities to other enzymatic activities (especially the mitochondrial external NADH dehydrogenase) is discussed.
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PMID:Pyridine nucleotide transhydrogenations in yeast. 390 68

The NADH and NADPH ferricyanide reductase activities present in mitochondrial NADH-CoQ reductase preparations have been studied utilizing two photoaffinity pyridine nucleotide analogues: arylazido-beta-alanyl NAD+ (A3'-O-[3-[N-(4-azido-2-nitrophenyl)amino]propionyl]NAD+) and arylazido-beta-alanyl NADP+ (N3'-O-[3-[N-(4-azido-3-nitrophenyl)amino]propionyl]NADP+). For the NADH-K3Fe(CN)6 reductase activity, arylazido-beta-alanyl NAD+ was found to be, in the dark, a competitive inhibitor with respect to both NADH and K3Fe(CN)6 with Ki,app values of 9.7 and 15.5 microM, respectively. In comparison the NADP+ analogue exhibited weak noncompetitive inhibitor activity for this reaction against both substrates. Upon photoirradiation arylazido-beta-alanyl NAD+ inhibited NADH-K3Fe(CN)6 reductase up to 70% in the presence of a 25-fold molar excess of analogue over the enzyme concentration. This photodependent inhibition could be prevented by the presence, during irradiation, of the natural substrate NADH. In contrast complex kinetic results were obtained with studies of the effects of the pyridine nucleotide analogues of NADPH-K3Fe(CN)6 reductase activity in the dark. Photoirradiation of either analogue in the presence of the enzyme complex resulted in an activation of NADPH-dependent activity. The possibility that the NADPH-K3Fe(CN)6 reductase activity of complex I represents a summation of the combined ferricyanide reductase activity of the NADPH-NAD+ transhydrogenase and NADH oxidoreductase is suggested.
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PMID:Studies of the ferricyanide reductase activities of the mitochondrial reduced nicotinamide adenine dinucleotide-ubiquinone reductase (complex I) utilizing arylazido-beta-alanyl NAD+ and arylazido-beta-alanyl NADP+. 392 31

Ferredoxin-NADP+ oxidoreductase (FNR, EC 1.18.1.2) was purified to molecular homogeneous form as judged by regular and sodium dodecyl sulfate (SDS)-electrophoresis using EDTA extraction of spinach thylakoids, followed by anion exchange on DEAE-cellulose, Procion Red HE 3B dye-ligand chromatography, and hydroxyapatite chromatography. By this procedure, within 1 week approx 7.5 mg of pure FNR, starting from 1 kg of spinach leaves, could be routinely obtained. By comparison with commercially available FNR and with aged preparations two different molecular forms of the enzyme were observed in SDS-electrophoresis. FNR prepared according to the described procedure revealed an apparent molecular mass of 36,000 Da, whereas all other tested preparations showed molecular masses of 3000 Da smaller. Migration in regular gel electrophoresis was the same for all preparations and zymogram stain indicated similar diaphorase activity of both the smaller and the larger forms.
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PMID:Rapid procedure for the preparation of ferredoxin-NADP+ oxidoreductase in molecularly pure form at 36 kDa. 408 75


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