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

---

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

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.
...
PMID:Energy transduction in the mitochondrionlike bacterium Paracoccus denitrificans during carbon- or sulphate-limited aerobic growth in continuous culture. 3 70

1. Respiration of chemotrophically and phototrophically grown Rhodospirillum rubrum is inhibited by 2-hydroxydiphenyl. 2. Membrane-bound NADH oxidase and NADH: cytochrome c reductase are inhibited also. The inhibitor constant for both reactions (Ki) is 0.075 plus or minus 0.012 mM. NADH dehydrogenase is not inhibited significantly. 3. The inhibition of succinate:cytochrome c reductase is associated for chemotrophic membranes with Ki equals 0.22 plus or minus 0.03 mM and for phototrophic membranes with Ki equals 0.49 plus or minus 0.09 mM. Succinate dehydrogenase is not affected by 2-hydroxydiphenyl. 4. Cytochrome oxidase is inhibited only slightly. 5. While NADH-dependent reactions in both phototrophic and chemotrophic membranes are inhibited maximally more than 95 percent, succinate-dependent reactions can be inhibited more than 95 percent only in chemotrophic membranes. In phototrophic membranes the maximum inhibition of succinate-dependent reactions is about 70 percent. 6. The type of inhibition in both cases 2 and 3 is non-competitive. 7. While the reduction of b-type cytochrome is inhibited by 2-hydroxydiphenyl, the degree of ubiquinone reduction is not influenced. The data suggest that the site of inhibition is localized between ubiquinone and cytochrome b. 8. Implications of these data for the respiratory electron transport system in R. rubrum are discussed.
...
PMID:Separation of respiratory reactions in Rhodospirillum rubrum: inhibition studies with 2-hydroxydiphenyl. 16 37

1. Electron transport particles obtained from cell-free extracts of Propionibacterium shermanii by centrifugation at 105000 times g for 3 hrs oxidized NADH, D,L-lactate, L-glycerol-3-phosphate and succinate with oxygen and, except for succinate, with fumarate, too. 2. Spectral investigation of the electron transport particles revealed the presence of cytochromes b, d and o, and traces of cytochrome alpha1 and a c-type cytochrome. Cytochrome b was reduced by succinate to about 50%, and by NADH, lactate or glycerol-3-phosphate to 80--90%. 3. The inhibitory effects of amytal and rotenone on NADH oxidation, but not on the oxidation of the other substrates, indicated the presence of the NADH dehydrogenase complex, or "site I region", in the electron transport system of P. shermanii. 4. NQNO inhibited substrate oxidations by oxygen and fumarate, as well as equilibration of the flavoproteins of the substrate dehydrogenases by way of menaquinone. The inhibition occurred at low concentrations of the inhibitor and reached 80--100%, depending on the substrate tested. The site of inhibition of the respiratory activity was located between menaquinone and cytochrome b. In addition, inhibition of flavoprotein equilibration suggested that NQNO acted upon the electron transfer directed from menaquinol towards the acceptor to be reduced, either cytochrome b or the flavoproteins, which would include fumarate reductase. 5. In NQNO-inhibited particles, cytochrome b was not oxidized by oxygen-free fumarate, but readily oxidized by oxygen. It was concluded from this and the above evidence that the branching-point of the electron transport chain towards fumarate reductase was located at the menaquinone in P. shermanii. It was further concluded that all cytochromes were situated in the oxygen-linked branch of the chain, which formed a dead end of the system under anaerobic conditions. 6. Antimycin A inhibited only oxygen-linked reactions of the particles to about 50% at high concentrations of the inhibitor. Inhibitors of terminal oxidases were inactive, except for carbon monoxide.
...
PMID:The electron transport system of the anaerobic Propionibacterium shermanii: cytochrome and inhibitor studies. 16 27

An NADH dehydrogenase possessing a specific activity 3-5 times that of membrane-bound enzyme was obtained by extraction of Acholeplasma laidlawii membranes with 9.0% ethanol at 43 degrees C. This dehydrogenase contained only trace amounts of iron (suggesting an uncoupled respiration), a flavin ratio of 1:2 FAD to FMN and 30-40% lipid. Its resistance to sedimentation is probably due to the high flotation density of the lipids. It efficiently utilized ferricyanide, menadione and dichlorophenol indophenol as electron acceptors, but not O2, ubiquinone Q10 or cytochrome c. Lineweaver-Burk plots of the dehydrogenase were altered to linear functions upon extraction with 9.0% ethanol. A secondary site of ferricyanide reduction could not be explained by the presence of cytochromes, which these membranes lack. In comparison to other respiratory chain-linked NADH dehydrogenases in cytochrome-containing respiratory chains, this dehydrogenase was characterized by similar Km's with ferricyanide, dichlorophenol indophenol, menadione as electron acceptors, but considerably smaller V's with ferricyanide, dichlorophenol indophenol, menadione as electron acceptors, and smaller specific activities. It was not stimulated or reactivated by the addition of FAD, FMN, Mg2+, cysteine or membrane lipids, and was less sensitive to respiratory inhibitors than unextracted enzyme. The ineffectiveness of ADP stimulation on O2 uptake, the insensitivity to oligomycin and the very low iron content of A. laidlawii membranes were considered in relation to conservation of energy by these cells. Some kinetic properties of the dehydrogenation, the uniquely high glycolipid content and apparently uncoupled respiration at Site I were noteworthy characteristics of this NADH dehydrogenase from the truncated respiratory chain of A. laidlawii.
...
PMID:The reduced nicotinamide adenine dinucleotide "oxidase" of Acholeplasma laidlawii membranes. 17 76

Oxidation of exogenous NADH in mitochondria isolated from wild type and mi-1 mutant of Neurospora crassa decreases rapidly in vitro. In mi-1 mutant mitochondria the inactivation concerns the alternate pathway of oxidation whereas in the wild type it involves an unknown component of the respiratory chain. The activity of the primary NADH dehydrogenase is constant within the time of the experiments (2-4 h). NADH oxidase is not inactivated if oxygen is removed from the incubation medium by nitrogen bubbling. Succinate oxidase does not show any remarkable changes in activity within 2-3 h. In fresh mitochondria of the mi-1 mutant reduced ubiquinone is completely reoxidized by cytochrome oxidase but only 80% reoxidized by the alternate oxidase. In aged mitochondria of the mi-1 mutant in the presence of cyanide, ubiquinone is reduced to the level characteristic for fresh mitochondria in which respiration is completely inhibited by cyanide plus salicylhydroxamic acid. In these mitochondria the reoxidation of the reduced ubiquinone proceeds only via the cytochrome pathway. It is supposed that a labile component(s) of the respiratory chain present in the mi-1 mutant and the wild type mitochondria may, in mi-1 mutant, act as an alternate oxidase.
...
PMID:Disappearance of the cyanide-insensitive pathway of oxidation in mitochondria of MI-1 mutant of Neurospora crassa in vitro. 20 34

Formate dehydrogenase, NADH dehydrogenase, a quinone and a b-type cytochrome characterized by maxima at 429 and 560 nm are shown to participate in the tetrathionate redox chain of Citrobacter.
...
PMID:Participation of quinone and cytochrome b in tetrathionate reductase respiratory chain of Citrobacter freundii. 43 81

The integral protein of cytochrome b556 after its solubilization with Triton X-100 from M. lysodeikticus membranes was studied. The cytochrome was found in complexes differing in charge and size during preparative gel electrophoresis and centrifugation in a sucrose concentration gradient. Cytochrome b556, being in complexes, retains its ability to be reduced by NADH dehydrogenase. The electron micrographs of the membranes after solubilization by Triton X-100 demonstrated the maintenance of the membrane structure. It is concluded that native protein complexes marked with cytochrome b556 are extracted from the membranes under their solubilization.
...
PMID:[Cytochrome b556 complexes solubilized from Micrococcus lysodeikticus membranes by triton X-100]. 43 82

Intact but fragile mitochondria were isolated from unsporulated oocysts of Eimeria tenella. The mitochondria respired in response to succinate, malate plus pyruvate, and L-ascorbate at rates of 1.00, 0.40, and 0.25 mu1 O2/min/mg protein, respectively. Spectrophotometric analyses of the cytochromes in mitochondria and whole oocysts revealed b-type and o-type cytochromes, at roughly similar levels, but no cytochrome c could be detected. The mitochondrial respiration was inhibited by cyanide, azide, carbon monoxide, antimycin A, and 2-heptyl-4-hydroxyquinoline-N-oxide, but was relatively resistant to rotenone and amytal. The quinolone coccidiostats buquinolate, amquinate, methyl benzoquate, and decoquinate were identified as very powerful inhibitiors of succinate and malate plus pyruvate supported respiration in E. tenella mitochondria. None of these four drugs exhibited any inhibitory effect on chicken liver mitochondria. Only 3 pmol of the quinolones per mg mitochondrial protein was needed to achieve 50% inhibition. The inhibition could not be reversed by coenzymes Q6 or Q10. Since the quinolones did not affect L-ascorbate-supported respiration or the activities of submitochondrial succinate dehydrogenase and NADH dehydrogenase, the site of action of the quinolone coccidiostats was tentatively identified as probably near cytochrome b in E. tenella mitochondria. Mitochondria isolated from an E. tenella amquinate-resistant mutant were much less susceptible to quinolone coccidiostats; 50% inhibition was attained by 300 pmol of the drugs/mg mitochondrial protein. The results suggest that the mechanisms of action of quinolone coccidiostats is by inhibiting the cytochrome-mediated electron transport in the mitochondria of coccidia. 2-Hydroxynaphthoquinone coccidiostats were identified as inhibitors of mitochondrial respiration of both E. tenella and chicken liver. They inhibited submitochondrial succinate dehydrogenase and NADH dehydrogenase of E. tenella, and remained equally active against the mitochondrial function of E. tenella amquinolate-resistant mutant.
...
PMID:Studies of the mitochondria from Eimeria tenella and inhibition of the electron transport by quinolone coccidiostats. 117 97

Preparations with a selectively decreased (by 85-90%) content of NADH dehydrogenase were isolated by means of heating treatment of M. lysodeikticus isolated membranes. The degree of the reduction of the NADH dehydrogenase nearest neighbour in the respiration chain of cytochrome b556 in heated membranes is similar to that in intact membranes. It is concluded that cytochrome b556 and (or) NADH dehydrogenase are capable to lateral migration in the membrane of M. lysodeikticus, resulting in the inter-chain electrone transport. A coefficient of their lateral diffusion is calculated (D equals 8-10(-10)-2-10(-9) CM2SEC-1 At 30 degrees C) on the basis of kinetics of cytochrome reduction by NADH dehydrogenase. The electron transport, due to a diffusion of respiration carriers from one assambly to another, proceeds 100 times as slow as the electrone transport in the respiratory chain. The data obtained allow to consider the aggregation of respiration enzymes as a dynamic formation.
...
PMID:[Lateral diffusion of the protein components of the respiratory assembly of Microsoccus lysodeikticus]. 121 62

A thirty-two year old female had chronic progressive external ophthalmoplegia (CPEO), exertional fatigue, dysarthria, dysphagia, and bilateral hearing impairment. Histochemical stains, obtained from the right vastus lateralis, showed ragged-red fibers and wide-spread abnormalities in the number, size, and the structure of mitochondria under electronomicroscopic examination. A biochemical analysis showed a low activity of NADH-cytochrome C reductase, NADH dehydrogenase and a normal activity of succinate cytochrome C reductase and cytochrome C oxidase. This data suggests a specific defect in the NADH dehydrogenase of complex I (NADH CoQ reductase). We believe that this is the first biochemically defined mitochondrial myopathy reported in Taiwan and provides additional evidence for the existence of biochemical heterogeneity in mitochondrial disorders of CPEO.
...
PMID:Chronic progressive external ophthalmoplegia with NADH-CoQ reductase deficiency: report of a case. 132 93


1 2 3 4 5 6 7 8 9 10 Next >>

---