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:1.6.99.5 (NADH dehydrogenase)
2,135 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Preparations of NADH-ubiquinone reductase from bovine heart mitochondria (Complex I) were shown to contain at least 16 polypeptides by gel electrophoresis in the presence of sodium dodecyl sulphate. 2. High-molecular-weight soluble NADH dehydrogenase prepared from Triton X-100 extracts of submitochondrial particles [Baugh & King (1972) Biochem. Biophys. Res. Commun. 49, 1165-1173] was similar to Complex I in its polypeptide composition. 3. Solubilization of Complex I by phospholipase A treatment and subsequent sucrose-density-gradient centrifugation did not alter the polypeptide composition. 4. Lysophosphatidylcholine treatment of Complex I caused some selective solubilization of a polypeptide of mol.wt. 33000 previosuly postulated to be the transmembrane component of Complex I in the mitochondrial membrane [Ragan (1975) in Energy Transducing Membranes: Structure, Function and Reconstitution (Bennun, Bacila & Najjar, eds.), Junk, The Hague, in the press]. 5. Chaotropic resolution of Complex I caused solubilization of polypeptides of molecular weights 75000, 53000, 29000, 26000 and 15500 and traces of others in the 10000-20000-mol.wt.range. 6. The major components of the iron-protein fraction from chaotropic resolution had molecular weights of 75000, 53000 and 29000, whereas the flavoprotein contained polypeptides of molecular weights 53000 and 26000 in a 1:1 molar ratio. 7. Iodination of Complex I by lactoperoxidase indicated that the water-soluble polypeptides released by chaotropic resolution, in particular those of the flavoprotein fraction, were largely buried in the intact Complex. 8. The polypeptides of molecular weights 75000, 53000, 42000, 39000, 33000, 29000 and 26000 were present in 1:2:1:1:1:1:1 molar proportions. The two subunits of molecular weight 53000 are probably non-identical.
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PMID:The structure and subunit composition of the particulate NADH-ubiquinone reductase of bovine heart mitochondria. 18 Sep 73

1. Previous studies have established that diphenyleneiodonium binds to and inhibits the respiratory enzyme NADH dehydrogenase and also catalyses an exchange of Cl- for OH- across membranes. 2. The hypoglycaemia produced by diphenyleneiodonium was confirmed and shown to be reversible at a dose of 4 mg/kg in starved rats. 3. The lethality of diphenyleneiodonium in mice was cumulative. 4. Presumably as a result of the Cl-/OH- exchange, diphenyleneiodonium-treated rats excreted less Cl- than controls in the first 12 h after administration. However, the swelling of erythrocytes observed in vitro did not occur in vivo. 5. When [125I]diphenyleneiodonium was administered to rats and rabbits, its distribution did not appear to be governed by its binding to NADH dehydrogenase. Reasons for this are discussed. 6 Over 90% of the radioactivity excreted in the faeces of rabbits could not be extracted with boiling water or with dil. HNO3.
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PMID:Some aspects of the pharmacology of diphenyleneiodonium, a bivalent iodine compound. 52 14

The structural gene of the Paracoccus denitrificans NADH-ubiquinone oxidoreductase encoding a homologue of the 75-kDa subunit of bovine complex I (NQO3) has been located and sequenced. It is located approximately 1 kbp downstream of the gene coding for the NADH-binding subunit (NQO1) [Xu, X., Matsuno-Yagi, A., and Yagi, T. (1991) Biochemistry 30, 6422-6428] and is composed of 2019 base pairs and codes for 673 amino acid residues with a calculated molecular weight of 73,159. The M(r) 66,000 polypeptide of the isolated Paracoccus NADH dehydrogenase complex is assigned the NQO3 designation on the basis of N-terminal protein sequence analysis, amino acid analysis, and immuno-cross-reactivity. The encoded protein contains a putative tetranuclear iron-sulfur cluster (probably cluster N4) and possibly a binuclear iron-sulfur cluster. An unidentified reading frame (URF3) which is composed of 396 base pairs and possibly codes for 132 amino acid residues was found between the NQO1 and NQO3 genes. When partial DNA sequencing of the regions downstream of the NQO3 gene was performed, sequences homologous to the mitochondrial ND-1, ND-5, and ND-2 gene products of bovine complex I were found, suggesting that the gene cluster carrying the Paracoccus NADH dehydrogenase complex contains not only structural genes encoding water-soluble subunits but also structural genes encoding hydrophobic subunits.
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PMID:Structural features of the 66-kDa subunit of the energy-transducing NADH-ubiquinone oxidoreductase (NDH-1) of Paracoccus denitrificans. 160 43

The inhibition of NADH dehydrogenase by 1-methyl-4-phenylpyridinium (MPP+) leading to ATP depletion has been proposed to explain cell death in the expression of the neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Electron paramagnetic resonance studies show no effect of MPP+ on the reduction of the iron-sulfur clusters of NADH dehydrogenase. Mitochondria inhibited by MPP+ were sonicated and both the NADH oxidase and the NADH-Q reductase activities were measured. NADH oxidase activity was not fully restored to control levels, but NADH-Q reductase activity was the same as that of the control. Neither succinate-oxidase nor succinate-Q reductase activities were inhibited. These data indicate that MPP+ interaction with NADH dehydrogenase interferes with the passage of electrons from the iron-sulfur cluster of highest potential to endogenous Q10 but that the inhibition can be relieved by the addition of a small, water-soluble Q analog. Inhibition at this site is sufficient to explain the inhibition of respiration and no inhibition of other mitochondrial functions was observed.
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PMID:The inhibition site of MPP+, the neurotoxic bioactivation product of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine is near the Q-binding site of NADH dehydrogenase. 282 83

Mitochondrial NADH dehydrogenase has been purified from rat liver mitochondria by protamine sulfate fractionation and DEAE-Sephadex chromatography. The enzyme is water-soluble and its molecular weight has been estimated at 400 +/- 50 kilodaltons. NADH-ferricyanide reductase and NADH cytochrome c reductase activities have been studied and the kinetic parameters have been determined. Both substrates, NADH and the electron acceptor (ferricyanide or cytochrome c) have an inhibitor effect on the reductase activities and the kinetic mechanism of the enzyme is ping-pong bi-bi.
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PMID:Isolation and characterization of a NADH-dehydrogenase from rat liver mitochondria. 361 8

The purified mitochondrial NADH dehydrogenase enzyme has been shown to catalyze a rapid [4B-3H] NADH-H2O exchange reaction. When the enzyme is subjected to a single freeze-thaw cycle there is a complete loss of NADH dehydrogenation without a measurable decrease in the [4B-3H] NADH-H2O exchange. Complete loss of the [4B-3H] NADH-H2O exchange follows brief exposure to ultraviolet photoirradiation. The differential sensitivity of the water exchange reaction and the dehydrogenase activity suggests a direct involvement of the enzymes flavin cofactor in the catalysis of the [4B-3H] NADH-H2O exchange. Arylazido-beta-alanyl NAD+ (A3'-0-[3-[N-4-azido-2-nitrophenyl)amino] propionyl]NAD+) is shown to be a potent photodependent inhibitor of the [4B-3H] NADH-H2O exchange activity following photoirradiation with visible light. This is consistent with the observed photodependent inhibition of the dehydrogenase activity by this photoprobe (Chen, S. and Guillory, R.J. (1981) J. Biol. Chem. 256, 8318-8323).
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PMID:The [4B-3H] NADH-H2O exchange reaction of the mitochondrial NADH dehydrogenase. 401 47

The NADH-dehydrogenase isolated from the M. lysodeikticus membranes was reconstituted into liposomes from the lipids obtained from the same membranes. The presence and degree of the reconstitution were investigated by two-dimensional immunoelectrophoresis and photoreactive hydrophobic label. The quenching of protein fluorescence by the aqueous quencher J- was practically the same for the enzyme in the reconstituted system and in the detergent solution, whereas the quencher interacting with the membrane--cetylpyridinium chloride--was effective in the first case and not effective in the second one. Evidence for the energy transfer from protein chromophores of NADH dehydrogenase in the proteoliposomes (lambda excit = 286 nm) to the hydrophobic fluorescent probe pyrene was obtained. It was found that about 30% of the chromophores in the enzyme molecule are involved in this process. The hydrophobic spin probe, whose paramagnetic fragment is located on the surface and not inside the hydrophobic phase of the membrane, can act as electron acceptor during NADH oxidation in the reconstituted system. The data obtained are suggestive of the exposure of the bulk of the enzyme molecule to the environment and of interaction of the smaller part of the molecule with the lipid phase. The active center is located on the part of the enzyme molecule which is exposed to water. It is assumed that the NADH-dehydrogenase molecule is exposed to water. It is assumed that the NADH-dehydrogenase molecule is involved in heat diffusion which facilitates the active center interaction with the membrane surface.
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PMID:[Interaction of NADH-dehydrogenase from M. lysodeikticus membranes with lipids in a reconstituted system]. 707 74

The main kinetic regularities of the NADH regeneration system functioning was studied. A theoretical interpretation of the dependence of the stationary reaction rate in a two-enzyme system with a common cofactor on the enzyme, cofactor and substrate concentrations and the catalytic parameters of individual enzymatic processes was obtained. A mathematical analysis of the dependences of the stationary rate on the content of each enzyme in the system at different activity ratios of each enzyme and within a broad range of initial cofactor concentrations was carried out. The kinetics of regeneration of native NADH and the NADH immobilized on a water-soluble 4-vinylpyridine and acroleine copolymer in a model two-enzyme formate dehydrogenase--NADH dehydrogenase system were investigated.
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PMID:[Kinetics of the NADH regenerating system using bacterial formate dehydrogenase]. 724 90

The proton-translocating NADH:ubiquinone oxidoreductase (complex I) was isolated from Escherichia coli by chromatographic steps performed in the presence of an alkylglucoside detergent at pH 6.0. The complex is obtained in a monodisperse state with a molecular mass of approximately 550,000 Da and is composed of 14 subunits. The subunits were assigned to the 14 genes of the nuo operon, partly based on their N-terminal sequences and partly on their apparent molecular masses. The preparation contains one noncovalently bound FMN/molecule. At least two binuclear (N1b and N1c) and three tetranuclear (N2, N3 and N4) iron-sulfur clusters were detected by EPR in the preparation when reduced with NADH. Their EPR characteristics remained mostly unaltered during the isolation process. After reconstitution in phospholipid membranes, the preparation catalyses piericidin-A-sensitive electron transfer from NADH to ubiquinone-2 with Km values similar to those of complex I in cytoplasmic membranes but with only 10% of the Vmax value. The isolated complex I was cleaved into three fragments when the pH was raised from 6.0 to 7.5 and the detergent exchanged to Triton X-100. One of these fragments is a water-soluble NADH dehydrogenase fragment which is composed of three subunits bearing at least four iron-sulfur clusters (N1b, N1c, N3 and N4) that can be reduced with NADH, one of them bearing FMN. The second, amphipathic, fragment, which is presumed to connect the NADH dehydrogenase fragment with the membrane, contains four subunits and at least one EPR-detectable iron-sulfur cluster whose spectral properties are reminiscent of the eucaryotic cluster N2. The third membrane fragment is composed of seven homologues of the mitochondrially encoded subunits of the eucaryotic complex I. This subunit arrangement coincidences to some extent with the order of the genes on the nuo operon. A topological model of the E. coli complex I is proposed.
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PMID:Isolation and characterization of the proton-translocating NADH: ubiquinone oxidoreductase from Escherichia coli. 760 27

The proton-translocating NADH-quinone oxidoreductase (NDH-1) of Paracoccus denitrificans is composed of at least 14 dissimilar subunits which are designated NQO1-14 and contains one noncovalently bound FMN and at least five EPR-visible iron-sulfur clusters (N1a, N1b, N2, N3, and N4) as prosthetic groups. Comparison of the deduced primary structures of the subunits with consensus sequences for the cofactor binding sites has predicted that NQO1, NQO2, NQO3, NQO9, and probably NQO6 subunits are cofactor binding subunits. Previously, we have reported that the NQO2 (25 kDa) subunit was overexpressed as a water-soluble protein in Escherichia coli and was found to ligate a single [2Fe-2S] cluster with rhombic symmetry (gx,y,z = 1.92, 1.95, and 2.00) (Yano, T., Sled', V.D., Ohnishi, T., and Yagi, T. (1994) Biochemistry 33, 494-499). In the present study, the NQO3 (66 kDa) subunit, which is equivalent to the 75-kDa subunit of bovine heart Complex I, was overexpressed in E. coli. The expressed NQO3 subunit was found predominantly in the cytoplasmic phase and was purified by ammonium sulfate fractionation and anion-exchange chromatography. The chemical analyses and UV-visible and EPR spectroscopic studies showed that the expressed NQO3 subunit contains at least two distinct iron-sulfur clusters: a [2Fe-2S] cluster with axial EPR signals (g perpendicular, parallel = 1.934 and 2.026, and L perpendicular parallel = 1.8 and 3.0 millitesla) and a [4Fe-4S] cluster with rhombic symmetry (gx,y,z = 1.892, 1.928, and 2.063, and Lx,y,z = 2.40, 1.55, and 1.75 millitesla). The midpoint redox potentials of [2Fe-2S] and [4Fe-4S] clusters at pH 8.6 are -472 and -391 mV, respectively. The tetranuclear cluster in the isolated NQO3 subunit is sensitive toward oxidants and converts into [3Fe-4S] form. The assignment of these iron-sulfur clusters to those identified in the P. denitrificans NDH-1 enzyme complex and the possible functional role of the NQO3 subunit is discussed.
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PMID:Expression and characterization of the 66-kilodalton (NQO3) iron-sulfur subunit of the proton-translocating NADH-quinone oxidoreductase of Paracoccus denitrificans. 762 45


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