Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Beta-Hydroxy-beta-methylglutaryl-coenzyme A reductase of yeast has been solubilized by two different methods and then purified approximately 5000-fold. The purified enzyme shows a single precipitin band on immunodiffusion, and it moves as a single band of protein and enzyme activity on gel filtration and diethylaminoethylcellulose column chromatography. It also shows one major band on polyacrylamide gel electrophoresis. The specific activity of the pure enzyme is 18 000 to 22 000 nmol of reduced nicotinamide adenine dinucleotide phosphate oxidized per min per mg of protein. The molecular weights of the enzyme, estimated by gel filtration, and the subunits, determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, are 2.6 X 10(5) and 6.0 X 10(4), respectively.
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PMID:Purification of beta-hydroxy-beta-methylglutaryl-coenzyme A reductase from yeast. 82 65

A ferredoxin containing only one [Fe4S4] cluster was purified from Clostridium thermoaceticum. It has a molecular weight of about 7,300, a partial specific volume of 0.67, and an isoelectric point of 3.25. Its absorption spectrum has two maxima at 390 nm (epsilon = 16.8 X 10(3)M-1cm-1) and at 280 nm (epsilon = 24.2 X 10(3)M-1cm-1). The absorption at 390 nm is almost half that of other clostridial ferredoxins, which have two [Fe4S4] clusters, and is similar to other ferredoxins with only one [Fe4S4] cluster. The ferredoxin had high thermal stability and retained over 50% of its activity after treatment at 80 degrees C. It functions in the transfer of electrons from pyruvate to nicotinamide adenine dinucleotide phosphate (NADP), which indicates the presence of pyruvate:ferredoxin oxidoreductase and reduced ferredoxin-NADP reductase in C, thermoaceticum. NADPH is used in the synthesis of acetate from CO2 in this organism.
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PMID:A four-iron, four-sulfide ferredoxin with high thermostability from Clostridium thermoaceticum. 86 52

Cell-free extracts of Methanobacterium thermoautotrophicum were found to contain high activities of the following oxidoreductases (at 60 degrees C): pyruvate dehydrogenase (coenzyme A acetylating), 275 nmol/min per mg of protein; alpha-ketoglutarate dehydrogenase (coenzyme A acylating), 100 nmol/min per mg; fumarate reductase, 360 nmol/min per mg; malate dehydrogenase, 240 nmol/min per mg; and glyceraldehyde-3-phosphate dehydrogenase, 100 nmol/min per mg. The kinetic properties (apparent V(max) and K(M) values), pH optimum, temperature dependence of the rate, and specificity for electron acceptors/donors of the different oxidoreductases were examined. Pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase were shown to be two separate enzymes specific for factor 420 rather than for nicotinamide adenine dinucleotide (NAD), NADP, or ferredoxin as the electron acceptor. Both activities catalyzed the reduction of methyl viologen with the respective alpha-ketoacid and a coenzyme A-dependent exchange between the carboxyl group of the alpha-ketoacid and CO(2). The data indicate that the two enzymes are similar to pyruvate synthase and alpha-ketoglutarate synthase, respectively. Fumarate reductase was found in the soluble cell fraction. This enzyme activity coupled with reduced benzyl viologen as the electron donor, but reduced factor 420, NADH, or NADPH was not effective. The cells did not contain menaquinone, thus excluding this compound as the physiological electron donor for fumarate reduction. NAD was the preferred coenzyme for malate dehydrogenase, whereas NADP was preferred for glyceraldehyde-3-phosphate dehydrogenase. The organism also possessed a factor 420-dependent hydrogenase and a factor 420-linked NADP reductase. The involvement of the described oxidoreductases in cell carbon synthesis is discussed.
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PMID:Oxidoreductases involved in cell carbon synthesis of Methanobacterium thermoautotrophicum. 91 79

The ultrastructural localization of 3 beta hydroxysteroid ferricyanide reductase, glucose-6-phosphate ferricyanide reductase and nicotinamide adenine dinucleotide and reduced form-ferricyanide reductase was investigated in some human steroidogenic tissues (corpus luteum of pregnancy, fetal adrenal gland and testis, adult testis and placenta) using ferricyanide as an electron acceptor. Copper ferrocyanide deposits were readily observed in the mitochondria, in the smooth endoplasmic reticulum profiles and in the cytoplasm. The sites of the various dehydrogenase activities could be visualized by using appropriate incubating media. The precise localization of various reactions in different electron transfer chains was determined by using different ferricyanide concentrations and intermediate electron-carriers such as menadione or exogenous nicotinamide adenine dinucleotide and reduced form-diaphorase. The use of respiratory chain inhibitors such as rotenone or antimycine A confirmed these data.
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PMID:The use of ferricyanide for the electron microscopic demonstration of dehydrogenases in human steroidogenic cells. 100 73

Since both transport activity and the leucine biosynthetic enzymes are repressed by growth on leucine, the regulation of leucine, isoleucine, and valine biosynthetic enzymes was examined in Escherichia coli K-12 strain EO312, a constitutively derepressed branched-chain amino acid transport mutant, to determine if the transport derepression affected the biosynthetic enzymes. Neither the iluB gene product, acetohydroxy acid synthetase (acetolactate synthetase, EC 4.1.3.18), NOR THE LEUB gene product, 3-isopropylmalate dehydrogenase (2-hydroxy-4-methyl-3-carboxyvalerate-nicotinamide adenine dinucleotide oxido-reductase, EC 1.1.1.85), were significantly affected in their level of derepression or repression compared to the parental strain. A number of strains with alterations in the regulation of the branched-chain amino acid biosynthetic enzymes were examined for the regulation of the shock-sensitive transport system for these amino acids (LIV-I). When transport activity was examined in strains with mutations leading to derepression of the iluB, iluADE, and leuABCD gene clusters, the regulation of the LIV-I transport system was found to be normal. The regulation of transport in an E. coli strain B/r with a deletion of the entire leucine biosynthetic operon was normal, indicating none of the gene products of this operon are required for regulation of transport. Salmonella typhimurium LT2 strain leu-500, a single-site mutation affecting both promotor-like and operator-like function of the leuABCD gene cluster, also had normal regulation of the LIV-I transport system. All of the strains contained leucine-specific transport activity, which was also repressed by growth in media containing leucine, isoleucine and valine. The concentrated shock fluids from these strains grown in minimal medium or with excess leucine, isoleucine, and valine were examined for proteins with leucine-binding activity, and the levels of these proteins were found to be regulated normally. It appears that the branched-chain amino acid transport systems and biosynthetic enzymes in E. coli strains K-12 and B/r and in S. typhimurium strain LT2 are not regulated together by a cis-dominate type of mechanism, although both systems may have components in common.
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PMID:Separate regulation of transport and biosynthesis of leucine, isoleucine, and valine in bacteria. 109 9

We have identified two distinct and consistent type I fiber subtypes in histochemically normal biopsies (vastus lateralis or biceps brachialis) from 12 healthy persons, both sexes, ages 15 to 42. The type I fibers were uniformly light with the regular ATPase (9.4) and uniformly dark with the acid-preincubated reverse ATPase reactions. However, the subtype IA fibers were stained darker than subtype IB fibers with the nicotinamide adenine nucleotide dehydrogenase-tetrazolium reductase, Oil red O, reduced nicotinamide adenine dinucleotide phosphate-tetrazolium reductase, nonspecific esterase, succinic-tetrazolium reductase, nicotinamide adenine dinucleotide-linked malic-tetrazolium reductase, and "nicotinamide adenine dinucleotide-linked lactic-tetrazolium reductase," and stained lighter with the phosphorylase, periodic acid-Schiff for glycogen, and menadione-mediated alpha-glycerophosphate-tetrazolium reductase reactions. The IB fibers were not as light (or as dark, depending on the stain) as any of the type II fibers. In one pathologic case, all the "hypotrophic type I muscle fibers with central nuclei" were subtype IB. In case of chronic infantile spinal atrophy the muscle showed some type-grouping and marked type I fiber predominance--the great majority of type I fibers were subtype IB, among which were islands (subtype-groups) of IA fibers. Subtyping of type I fibers may be informative in evaluating the pathologic process of certain human neuromuscular diseases.
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PMID:Distinct subtypes of type I fibers of human skeletal muscle. 117 13

1 (-)Emetine (0.25-2.0 mg/kg i.p.) was administered to rats for up to 220 days. 2 At doses of 1.0 mg/kg or less, the animals continued to gain weight but more slowly than the untreated control animals. The physiological changes in the muscles from these animals were minimal; there was a small reduction in both the resting membrane potential and in the maximum rate of rise of the action potential. There was no atrophy or loss of muscle fibres although in the occasional muscle, hyaline fibres, necrotic fibres and split fibres were observed. There was a focal loss of myofibrillar adenosine triphosphatase (ATPase) and nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR) in Type II and Type III fibres, but no such loss in Type I fibres. 3 The animals receiving 2.0 mg/kg of (-)emetine gained weight slowly for up to 20 days but then rapidly lost weight and by 30 days they were weak and emaciated. The muscles from these animals were severly atrophied and the total muscle wet weight was reduced by almost 20%. 4 The strength of the muscles from these animals was measured in vitro using direct stimulation. They were weaker than normal both in absolute terms and when expressed in terms of tension developed/unit wet weight. 5 There was no evidence of either functional or structural denervation but surgically denervated muscles from animals in this group were indistinguishable from denervated muscles from normal rats. 6 Severe structural damage was obvious in the fibres of both extensor digitorum longus and soleus. Necrotic, hyaline and splitting fibres were common and the focal loss of myofibrillar ATPase and NADH-TR activity was extensive and occurred in Type I fibres as well as in Type II and Type II fibres. 7 It is concluded that the muscular weakness induced by (-)-emetine is due to a direct effect on the muscle fibres and that this occurs at a subcellular level. There is no evidence that functional or structural denervation plays any role in the aetiology of emetine myopathy in the rat.
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PMID:Emetine myopathy in the rat. 127 39

Phthalate dioxygenase reductase (PDR) is a prototypical iron-sulfur flavoprotein (36 kilodaltons) that utilizes flavin mononucleotide (FMN) to mediate electron transfer from the two-electron donor, reduced nicotinamide adenine nucleotide (NADH), to the one-electron acceptor, [2Fe-2S]. The crystal structure of oxidized PDR from Pseudomonas cepacia has been analyzed at 2.0 angstrom resolution resolution; reduced PDR and pyridine nucleotide complexes have been analyzed at 2.7 angstrom resolution. NADH, FMN, and the [2Fe-2S] cluster, bound to distinct domains, are brought together near a central cleft in the molecule, with only 4.9 angstroms separating the flavin 8-methyl and a cysteine sulfur ligated to iron. The domains that bind FMN and [2Fe-2S] are packed so that the flavin ring and the plane of the [2Fe-2S] core are approximately perpendicular. The [2Fe-2S] group is bound by four cysteines in a site resembling that in plant ferredoxins, but its redox potential (-174 millivolts at pH 7.0) is much higher than the potentials of plant ferredoxins. Structural and sequence similarities assign PDR to a distinct family of flavoprotein reductases, all related to ferredoxin NADP(+)-reductase.
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PMID:Phthalate dioxygenase reductase: a modular structure for electron transfer from pyridine nucleotides to [2Fe-2S]. 128 Aug 57

Purified cerebellar nitric oxide (NO) synthase was found to reduce molecular oxygen to hydrogen peroxide at low concentrations of its substrate L-arginine or its cofactor tetrahydrobiopterin. The characteristics of oxygen reduction appeared to be similar to NO synthesis, as both reactions required reduced nicotinamide adenine dinucleotide phosphate (NADPH), were dependent on Ca2+/calmodulin, and showed optimal reaction rates at slightly acidic conditions. The electron transport from NADPH to molecular oxygen is probably mediated by the reduced flavins, flavine adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which are bound in stoichiometrical amounts to the enzyme. NO synthase shows similarities to cytochrome P450 (cytochrome c) reductase, another FAD- and FMN-containing enzyme, and we found that NO synthase reduced cytochromes and artificial, low molecular mass electron acceptors in a superoxide dismutase-insensitive manner. Thus, NO synthase apparently represents a Ca(2+)-regulated, soluble isoform of cytochrome P450 reductase.
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PMID:Nitric oxide synthase-catalyzed activation of oxygen and reduction of cytochromes: reaction mechanisms and possible physiological implications. 128 86

Acetonitrile extracts of cigarette tar inhibit state 3 and state 4 respiration of intact mitochondria. Exposure of respiring submitochondrial particles to acetonitrile extracts of cigarette tar results in a dose-dependent inhibition of oxygen consumption and reduced nicotinamide adenine dinucleotide (NADH) oxidation. This inhibition was not due to a solvent effect since acetonitrile alone did not alter oxygen consumption or NADH oxidation. Intact mitochondria are less sensitive to extracts of tar than submitochondrial particles. The NADH-ubiquinone (Q) reductase complex is more sensitive to inhibition by tar extract than the succinate-Q reductase and cytochrome complexes. Nicotine or catechol did not inhibit respiration of intact mitochondria. Treatment of submitochondrial particles with cigarette tar results in the formation of hydroxyl radicals, detected by electron spin resonance (ESR) spin trapping. The ESR signal attributable to the hydroxyl radical spin adduct requires the presence of NADH and is completely abolished by catalase and to a lesser extent superoxide dismutase (SOD). Catalase and SOD did not protect the mitochondrial respiratory chain from inhibition by tar extract, indicating that the radicals detected by ESR spin trapping are not responsible for the inhibition of the electron transport. We propose that tar causes at least two effects: (1) Tar components interact with the electron transport chain and inhibit electron flow, and (2) tar components interact with the electron transport chain, ultimately to form hydroxyl radicals.
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PMID:The inhibitory effect of extracts of cigarette tar on electron transport of mitochondria and submitochondrial particles. 131 24


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