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:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Treatment of the soluble ubiquinone-deficient succinate: ubiquinone reductase with pyridoxal phosphate results in the inhibition of the carboxin-sensitive ubiquinone-reductase activity of the enzyme. The inactivation is prevented by the soluble homolog of ubiquinone (Q2) but is insensitive to the dicarboxylates interacting with the substrate binding site of succinate dehydrogenase. The reactivity of the pyridoxal phosphate-inhibited enzyme with different electron acceptors suggests that the observed inhibition is due to the dissociation of succinate dehydrogenase from the enzyme complex. The soluble succinate dehydrogenase was recovered in the supernatant after treatment of the insoluble succinate: ubiquinone reductase with pyridoxal phosphate. The data obtained strongly suggest the participation of amino groups in the interaction between succinate dehydrogenase and the ubiquinone reactivity conferring peptide within the complex.
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PMID:Pyridoxal phosphate-induced dissociation of the succinate: ubiquinone reductase. 397 21

Thenoyltrifluoroacetone (TTA) and carboxin inhibit soluble ubiquinone-deficient succinate: ubiquinone reductase according to the mixed type (with respect to added Q2) inhibition. pattern. The Ki values for the inhibitors are mutually dependent, thus indicating the presence of a single binding site for both TTA and carboxin. The enolic form of TTA was shown to be the species interacting with the enzyme. Carboxin prevents the alkali-induced inactivation of the membrane-bound succinate dehydrogenase without having any effect on the reconstitution of succinate: ubiquinone reductase from the soluble dehydrogenase and b-c1 complex. The reduction of the respiratory chain by succinate protects succinate dehydrogenase against inactivation (solubilization) by alkali; under these conditions, carboxin does not affect the inactivation process. The cumulative data suggest that the degree of the mutual mobility of the succinate dehydrogenase smaller subunit and ubiquinone reactivity-conferring protein (QPs) is a prerequisite for the catalytic mechanism of succinate: ubiquinone reductase. A mechanism of the enzyme inhibition by TTA and carboxin is proposed, which consists in non-covalent cross-linking of the subunits by the inhibitors.
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PMID:[Interaction of mitochondrial succinate:ubiquinone reductase with thenoyltrifluoroacetone and carboxin]. 399 1

1. Assay conditions are described for the ATP-dependent, uncoupler-sensitive, energy-linked reduction of NAD(+) by succinate, dl-alpha-glycerophosphate or d-lactate in membranes from aerobically grown Escherichia coli. 2. The reaction may be demonstrated in electron-transport particles (ET particles) from cells grown in glycerol, but not in depleted particles washed in low-ionic-strength buffer, or in ET particles from cells grown in glucose. 3. The latter two classes of particles have low specific activities of ATPase (adenosine triphosphatase), succinate dehydrogenase, dl-alpha-glycerophosphate dehydrogenase and d-lactate dehydrogenase relative to undepleted ET particles from cells grown in glycerol. 4. Reconstitution of energy-linked NAD(+) reduction in particles from cells grown in glucose was done by: (a) addition of the high-speed supernatant fraction from sonicates of the same cells; (b) addition of a protein fraction, precipitated by (NH(4))(2)SO(4) from this supernatant, or (c) addition of an (NH(4))(2)SO(4)-precipitated fraction from the low-ionic-strength wash of particles from cells grown in glycerol. 5. The use of (NH(4))(2)SO(4)-precipitated fractions from ATPase- or succinate dehydrogenase-deficient mutants grown in glycerol in the above reconstitution indicated that failure to demonstrate the reaction in particles from cells grown in glucose was a result of inadequate activities of appropriate dehydrogenases, rather than of ATPase. 6. Energy-linked NAD(+) reduction could be demonstrated in particles from a ubiquinone-deficient mutant only after restoration of NADH oxidase activity by adding ubiquinone-1. 7. The measured rate of the energy-linked reaction in particles from a haem-deficient mutant, however, was not stimulated after the ATP- and haematin-dependent acquisition of functional cytochromes. 8. Results are interpreted as evidence of the ubiquinone-dependent, but cytochrome-independent, nature of the site I region of the respiratory chain in E. coli.
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PMID:Energy-linked reduction of nicotinamide--adenine dinucleotide in membranes derived from normal and various respiratory-deficient mutant strains of Escherichia coli K12. 415 32

1. Exposure of rats to low environmental temperature resulted in increased activities of several hepatic oxidative-enzyme systems. 2. Simultaneous with increase in liver ubiquinone in cold-exposed rats, the ubiquinone-dependent succinate-neotetrazolium chloride reductase activity also increased. Such an increase could also be obtained by enriching liver with ubiquinone by feeding with an exogenous source. 3. Succinate-neotetrazolium chloride reductase activity could be increased by preincubation of mitochondria with succinate and the mechanism of this activation appears to be different from that obtained on addition of ubiquinone. 4. Succinate-neotetrazolium chloride reductase activity was found to be more labile than succinate dehydrogenase on freezing and thawing and storage, and the presence of succinate gave protection against this loss in hepatic mitochondria obtained from both normal and cold-exposed animals.
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PMID:Changes in the liver mitochondrial oxidation of succinate during cold-exposure. 433 Sep 7

Saccharomyces cerevisiae was grown in batch culture over a wide range of oxygen concentrations, varying from the anaerobic condition to a maximal dissolved oxygen concentration of 3.5 muM. The development of cells was assayed by measuring amounts of the aerobic cytochromes aa(3), b, c, and c(1), the cellular content of unsaturated fatty acids and ergosterol, and the activity of respiratory enzyme complexes. The half-maximal levels of membrane-bound cytochromes aa(3), b, and c(1), were reached in cells grown in O(2) concentrations around 0.1 muM; this was similar to the oxygen concentration required for half-maximal levels of unsaturated fatty acid and sterol. However, the synthesis of ubiquinone and cytochrome c and the increase in fumarase activity were essentially linear functions of the dissolved oxygen concentration up to 3.5 muM oxygen. The synthesis of the succinate dehydrogenase, succinate cytochrome c reductase, and cytochrome c oxidase complexes showed different responses to changes in O(2) concentration in the growth medium. Cyanide-insensitive respiration and P(450) cytochrome content were maximal at 0.25 muM oxygen and declined in both more anaerobic and aerobic conditions. Cytochrome c peroxidase and catalase activities in cell-free homogenates were high in all but the most strictly anaerobic cells.
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PMID:Respiratory development in Saccharomyces cerevisiae grown at controlled oxygen tension. 435 79

1. A spectroscopic resolution has been made of the components contributing to the ;iron-flavoprotein' trough extending from 450 to 520nm in the reduced-minus-oxidized difference spectrum of submitochondrial particles of Torulopsis utilis. 2. Seven components were identified other than cytochrome b, ubiquinone and succinate dehydrogenase. On the basis of the effects of iron- and sulphate-limited growth of cells on their subsequently derived electron-transport particles, and also by consideration of analytical measurements of the concentration of FMN, FAD, non-haem iron and acid-labile sulphide in the electron-transport particles in relation to the magnitude of the spectroscopic changes, it was possible to identify five of these components as follows: species 1a, the flavin of NADH dehydrogenase ferroflavoprotein; species 1b, the iron-sulphur component of NADH dehydrogenase ferroflavoprotein; species 1', the flavin of an NADPH dehydrogenase; species 2, an iron-sulphur or ferroflavoprotein component; species 3, the flavin of l-3-glycerophosphate dehydrogenase. Two additional components were a fluorescent flavoprotein, probably lipoamide dehydrogenase, and a b-type cytochrome reducible by NADH or NADPH but not reoxidizable by the respiratory chain. 3. Species 1b and 2 were undetectable in electron-transport particles from iron- or sulphate-limited cells, but could be recovered in vivo under non-growing conditions. 4. The recovery in vivo of species 2 but not species 1b was inhibited by cycloheximide. 5. The recovery of species 1b correlates with the recovery of site 1 conservation. 6. The recovery of species 1b with species 2 correlates with the recovery of piericidin A sensitivity. 7. Evidence is presented for an NADPH dehydrogenase distinct from NADH dehydrogenase. The oxidation of NADH and NADPH by the respiratory chain is sensitive to piericidin A, and an iron-sulphur protein common to both pathways (species 2) is suggested as the piericidin A-sensitive component. 8. The approximate E'(0) (pH7.0) values of species 1 (a and b, low potential) and species 2 (high potential) indicate that site 1 energy conservation occurs between the levels of species 1 (a and b) and species 2.
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PMID:Spectroscopic studies of flavoproteins and non-haem iron proteins of submitochondrial particles of Torulopsis utilis modified by iron- and sulphate-limited growth in continuous culture. 439 18

1. Exposure of Astasia longa to oxygen+carbon dioxide (95:5) at atmospheric pressure leads to an inhibition of growth rate and of respiration. Growth resumes at the normal rate as soon as the oxygenation is discontinued, but respiration recovers more slowly. 2. Mitochondria prepared from cells exposed to oxygen+carbon dioxide (95:5) during growth have considerably decreased activities of succinate-cytochrome c oxidoreductase, NADH-cytochrome c oxidoreductase, succinate dehydrogenase and succinate oxidase activities as compared with mitochondria obtained from cells exposed to air+carbon dioxide (95:5). Cytochrome oxidase activity is not appreciably inhibited by exposure of the cells to 95% oxygen. 3. The mitochondrial fraction of Astasia contains rhodoquinone. The rhodoquinone concentration increases in cells exposed to 95% oxygen. The content of ergosterol-containing compounds also increases in the mitochondria of cells exposed to 95% oxygen. There is little change in the ubiquinone content of the mitochondrial fraction. The ubiquinone of Astasia appears to be ubiquinone-45.
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PMID:Oxygen toxicity in Astasia. 558 20

Iron-sulfur clusters present in rat liver submitochondrial particles were characterized by ESR at temperatures between 30 and 5.5 K combined with potentiometric titrations. The spectral and thermodynamic characteristics of the iron-sulfur clusters were generally similar to those previously reported for pigeon or bovine heart submitochondrial particles. Clusters N-1a, N-1b, N-2, N-3 and N-4 of NADH dehydrogenase had midpoint oxidation-reduction potentials at pH 7.5 of -425, -265, -85, -240 and -260 mV, respectively. Clusters S-1 and S-3 of succinate dehydrogenase had midpoint potentials of 0 and +65 mV, respectively. The iron-sulfur cluster of electron-transferring flavo-protein-ubiquinone oxidoreductase exhibited the gz signal at g = 2.08 and had a midpoint potential of +30 mV. This signal was relatively prominent in rat liver compared to pigeon or bovine heart. Submitochondrial particles from rats chronically treated with ethanol (36% of total calories, 40 days) showed decreases of 20-30+% in amplitudes of signals due to clusters N-2, N-3 and N-4 compared to those from pair-fed control rats. Signals from clusters N-1b, S-1, S-3 and electron-transferring flavoprotein-ubiquinone oxidoreductase were unaffected. Microwave power-saturation behavior was similar for both submitochondrial particle preparations, suggesting that the lower signal amplitudes reflected a lower content of these particular clusters. NADH dehydrogenase activity was significantly decreased (46%), whilst succinate dehydrogenase activity was elevated (25%), following chronic ethanol consumption. The results indicate that chronic ethanol treatment leads to an alteration of the structure and function of the NADH dehydrogenase segment of the electron transfer chain. This alteration is one of the factors contributing to the lower respiration rates observed following chronic ethanol administration.
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PMID:Characterization of iron-sulfur clusters in rat liver submitochondrial particles by electron paramagnetic resonance spectroscopy. Alterations produced by chronic ethanol consumption. 624 7

The kinetics of the succinate oxidation by cyanide-sensitive and cyanide-insensitive submitochondrial particles of Neurospora crassa cells suggest that both respiratory pathways use the same complex II. This is confirmed by comparing the kinetics of the reductase activities of the isolated succinate-ubiquinone oxidoreductase (complex II) of cyanide-sensitive and cyanide-insensitive cells respectively. No alternative-oxidase activity was found to be associated with the isolated complex II of cyanide-insensitive cells.
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PMID:Substrate kinetics of the alternative oxidase of Neurospora crassa. 644

The rates of the oxidized (Eox) and reduced (Ered) (by NAD . H through the ubiquinone pool) succinate dehydrogenase inhibition by N-ethyl-maleimide are equal and obey pseudo-first order kinetics. The protection of the enzyme against irreversible alkylation was used to quantitate the dissociation constants for Eox and Ered complexes with fumarate, succinate and malonate under conditions when no intramolecular redox reactions might occur. the membrane-bound succinate dehydrogenase catalyzes the succinate : phenazine-methosulphate reductase reaction in the presence of thenoyltrifluoroacetone by a Slater-Bonner mechanism. A comparison of the constants measured by the protection with those derived from the steady-state kinetics shows that succinate affinity for Eox is about 10 times higher than that for Ered; the reverse relations were found for fumarate, whereas the affinity for malonate only slightly depends on the redox state of the enzyme. The data obtained suggest that the dicarboxylate binding at the active site induces changes in the enzyme redox potential. The surface charge does not contribute significantly to the energy of the dicarboxylate binding to the active site of the membrane-bound enzyme.
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PMID:[Dissociation constants of succinate dehydrogenase complexes with succinate, fumarate and malonate]. 672 18


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