Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 activities of microsomal stearoyl-CoA desaturation, NADH-cytochrome b5 reductase, NADH-cytochrome c reductase, and the content of cytochrome b5 were similar in livers of normal and host rats. On the other hand, stearoyl-CoA desaturation activity was absent in Novikoff hepatoma. The activities of NADH-cytochrome b5 and NADH-cytochrome c reductases in the hepatoma microsomes were 4.8% and 2.2%, respectively, of those in normal liver. Furthermore, in hepatoma microsomes, cytochrome b5 was absent. An active stearoyl-CoA desaturation was reconstituted only on addition of both cytochrome b5 and the terminal desaturase enzyme to the hepatoma microsomes. These results indicated that a complete absence of cytochrome b5 and terminal desaturase is responsible for the lack of stearoyl-CoA desaturation in Novikoff hepatoma microsomes.
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PMID:Stearoyl-coenzyme A desaturase activity in Novikoff hepatoma. 3 26

Paracoccus denitrificans was grown in carbon-limited aerobic continuous culture (critical dilution rate (Dc) = 0.48 h-1). The molar growth yield for carbon (succinate or malate) was constant at about 60 over a broad dilution range (growth rate) from 0.10 to 0.48 h-1. Measurements of the stoichiometry of proton translocation associated with the oxidation of endogenous substrates yielded a ratio of protons ejected from the cell per atom of oxygen consumed(leads to H+:O) of 8.55 which decreased to 5.85 in the presence of piericidin A (PA), a specific inhibitor of NADH dehydrogenase (EC 1.6.99.3). With starved cells, the observed leads to H+:O associated with the oxidation of added succinate in the presence of PA was 5.61. These observed leads to H:O's represent an underestimation since no correction was made for proton backflow during the short interval of respiratory activity. Aerobic growth of Pc. denitrificans in the chemostat becomes sulphate limited at entering concentrations of sulphate less than 300 is microM. Neither the maximum specific growth rate (measured at Dc) nor the observed molar growth yield for succinate decreased under sulphate limitation. The NADH oxidase in electron transport particles prepared from sulphate-limited cells was completely inhibited by PA. The stoichiometry of proton translocation associated with malate oxidation was similarly unaffected by sulphate limitation. It is concluded that (a) the respiratory chain of aerobic, heterotrophically grown Pc. denitrificans possesses three sites of energy conservation, including site III, (b) the number of protons ejected during the transfer of one pair of reducing equivalents along a region of the electron transport chain equivalent to a single energy-coupling site is 3, and (c) that sulphate limitation does not lead to a loss of proton translocation associated with the cytochrome-independent region of the respiratory chain.
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PMID:Energy transduction in the mitochondrionlike bacterium Paracoccus denitrificans during carbon- or sulphate-limited aerobic growth in continuous culture. 3 70

1. Electron paramagnetic resonance spectra at 8-60 K of NADH-reduced membrane particles prepared from Paracoccus denitrificans grown anaerobically with nitrate as terminal electron acceptor show the presence of iron-sulfur centers 1-4 in the NADH-ubiquinone segment of the respiratory chain. In addition resonance lines at g = 2.058, g = 1.953 and g = 1.88 are detectable in the spectra of succinate-reduced membranes at 15 K, which are attributed to the iron-sulfur-containing nitrate reductase. 2. Sulphate-limited growth under anaerobic conditions does not affect the iron-sulfur pattern of NADH dehydrogenase or nitrate reductase. Furthermore respiratory chain-linked electron transport and its inhibition by rotenone are not influenced. These results contrast those observed for sulphate-limited growth of P. denitrificans under aerobic conditions [Eur. J. Biochem. (1977) 81, 267-275]. 3. Proton translocation studies of whole cells indicate that nitrite increases the proton conductance of the cytoplasmic membrane, resulting in a collapse of the proton gradient across the membrane. Nitrite accumulates under anaerobic growth conditions with nitrate as terminal electron acceptor; the extent of accumulation depends on the specific growth conditions. Thus the low efficiencies of respiratory chain-linked energy conservation observed during nitrate respiration [Arch. Microbiol. (1977) 112, 17-23] can be explained by the uncoupling action of nitrite.
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PMID:Anaerobic respiration and energy conservation in Paracoccus denitrificans. Functioning of iron-sulfur centers and the uncoupling effect of nitrite. 3 82

We have shown that skin fibroblast from patients with cystic fibrosis (CF) and from carriers for CF [heterozygotes (HZ)] consume more O2 than do their controls. When the mitochondrial electron transport inhibitor rotenone was added to the cells, the relative inhibition of O2 consumption was CF greater than HZ greater than controls (P less than 0.005 in both comparisons). Because rotenone specifically inhibits NADH dehydrogenase, [NADH: (acceptor) oxidoreductase, EC 1.6.99.3], which is the enzyme of energy-conserving site 1 of the mitochondrial electron transport system, activity and kinetics of this enzyme system were studied in fibroblast homogenates. NADH dehydrogenase activity was equal in cells from the three genotypes. At pH 8.0, affinity of the enzyme for its substrate was CF greater than HZ = controls; at pH 8.6, affinity was CF greater than HZ = controls (P less than 0.005 for the differences). pH optima for the genotypes were without exception 8.6 (CF), 8.3 (HZ), and 8.0 (control). HZ and control lines were distinguished unequivocally in a blind test on the basis of differences in pH optima. Purified mitochondrial preparations revealed pH optima identical to those found in whole cell homogenates. These data suggest that the mutant gene responsible for CF is expressed in the complex mitochondrial NADH dehydrogenase system.
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PMID:Mitrochondrial NADH dehydrogenase in cystic fibrosis. 3 4

1. Both NADH and NADPH supported the oxidation of adrenaline to adrenochrome in bovine heart submitochondrial particles. The reaction was completely inhibited in the presence of superoxide dismutase, suggesting that superoxide anions (O(2) (-)) are responsible for the oxidation. The optimal pH of the reaction with NADPH was at pH7.5, whereas that with NADH was at pH9.0. The reaction was inhibited by treatment of the preparation with p-hydroxymercuribenzoate and stimulated by treatment with rotenone. Antimycin A and cyanide stimulated the reaction to the same extent as rotenone. The NADPH-dependent reaction was inhibited by inorganic salts at high concentrations, whereas the NADH-dependent reaction was stimulated. 2. Production of O(2) (-) by NADH-ubiquinone reductase preparation (Complex I) with NADH or NADPH as an electron donor was assayed by measuring the formation of adrenochrome or the reduction of acetylated cytochrome c which does not react with the respiratory-chain components. p-Hydroxymercuribenzoate inhibited the reaction and rotenone stimulated the reaction. The effects of pH and inorganic salts at high concentrations on the NADH- and NADPH-dependent reactions of Complex I were essentially similar to those on the reactions of submitochondrial particles. 3. These findings suggest that a region between a mercurialsensitive site and the rotenone-sensitive site of the respiratory-chain NADH dehydrogenase is largely responsible for the NADH- and NADPH-dependent O(2) (-) production by the mitochondrial inner membranes.
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PMID:NADH- and NADPH-dependent formation of superoxide anions by bovine heart submitochondrial particles and NADH-ubiquinone reductase preparation. 3 43

This new assay procedure for diaphorase eliminates problems of high blank rates and nonlinear kinetics associated with other methods. The dye thiazolyl blue tetrazolium bromide is reduced in the presence of NADH and diaphorase to yield a colored formazan, which as maximum absorbance at 560 nm.
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PMID:A new assay for diaphorase activity in reagent formulations, based on the reduction of thiazolyl blue. 4 50

Methemoglobinemia and mental retardation associated with NADH-diaphorase deficiency was found in a 2-year-old girl of Spanish origin. She showed no NADH-diaphorase activity in either erythrocytes or leukocytes, but electrophoretic studies of the hemolysate showed traces of an enzyme with normal mobility. Cytochrome b5 reductase activity was also found to be absent in the leukocytes of the propostius. Intermediate NADH-diaphorase activity was found in erythrocytes and leukocytes in her parents and her sister in accordance with the autosomal recessive mode of inheritance of this enzymopathy. The relationship between a generalized cytochrome b5 reductase deficiency and the progressive neurological involvement in our patient is discussed briefly.
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PMID:Congenital methemoglobin-reductase (cytochrome b5 reductase) deficiency associated with mental retardation in a Spanish girl. 9 93

The action of two radioprotectors--cysteamine and cystamine--on the liver microsomal multi-enzyme hydroxylating system, a key stem in drug and biological compounds metabolism, has been studied. Their effects have been systematically analysed at the level of individual enzyme activities and global functions. The two compounds are quite inactive on NADPH and NADH cytochrome c reductase activities, but slightly denature the cytochrome P450 into cytochrome P420. Furthermore, they do inhibit to some extent (30 per cent at 10(-2) M) the rate of codeine hydroxylation and totally suppress ((at 10(-2) M) the NADPH-induced lipid peroxidation which occurs during enzymatic functioning. These results are discussed in the light of the toxicity of radioprotectors.
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PMID:Biochemical effects on radioprotective agents on the liver microsomal hydroxylating system: in vitro studies. 9 66

Cytochrome b5 was isolated from liver microsomes using a detergent-method. The hemoprotein was found to bind to liver plasma membranes in vitro and was accompanied by an increase in NADH-cytochrome c reductase activity, but not NADH-ferricyanide reductase activity. As in the case of microsomes, the binding to plasma membranes was temperature-dependent and was tight to the extent that the bound cytochrome b5 was little released under high ionic strength. The capacity of plasma membranes for the binding was less than that of microsomes. Administration of CCl4 did not significantly affect the binding of the hemoprotein in both fractions. These results add support to our previous proposal that the elevation of NADH-cytochrome c reductase activity of liver plasma membranes observed early after administration of CCl4 may be caused by the binding of cytochrome b5 which has probably migrated from the endoplasmic reticulum.
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PMID:Studies on the function of cell membrane. 11th Report: Binding of cytochrome b5 to liver microsomes and plasma membranes isolated from normal and CCl4-treated rats. 9 90

The involvement of cytochrome b5 in palmitoyl-CoA desaturation by yeast microsomes was studied by using yeast mutants requiring unsaturated fatty acids and an antibody to yeast cytochrome b5. The mutants used were an unsaturated fatty acid auxotroph (strain E5) and a pleiotropic mutant (strain Ole 3) which requires either Tween 80 and ergosterol or delta-aminolevulinic acid for growth. Microsomes from the wild-type strain possessed both the desaturase activity and cytochrome b5, whereas those from mutant E5 contained the cytochrome but lacked the desaturase activity. Microsomes from mutant Ole 3 grown with Tween 80 plus ergosterol were devoid of both the desaturase activity and cytochrome b5, but those from delta-aminolevulinic acid-grown mutant Ole 3 contained cytochrome b5 and catalyzed the desaturation. The cytochrome b5 content in microsomes from mutant Ole 3 could be varied by changing the delta-aminolevulinic acid concentration in the growth medium, and the desaturase activity of the microsomes increased as their cytochrome b5 content was increased. The antibody to yeast cytochrome b5, but not the control gamma-globulin fraction, inhibited the NADH-cytochrome c reductase and NADH-dependent desaturase activities of the wild-type microsomes. It is concluded that cytochrome b5 is actually involved in the desaturase system of yeast microsomes. The lack of desaturase activity in mutant Ole 3 grown with Tween 80 plus ergosterol seems to be due to the absence of cytochrome b5 in microsomes, whereas the genetic lesion in mutant E5 appears to be located at ther terminal desaturase.
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PMID:Mutant and immunochemical studies on the involvement of cytochrome b5 in fatty acid desaturation by yeast microsomes. 10 93


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