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)

The succinate dehydrogenase isolated from Bacillus subtilis was found to catalyze the oxidation of succinate with hydrophilic quinones. Either naphthoquinones or benzoquinones served as acceptors. The enzyme activity increased with the redox potential of the quinone. The highest turnover number was commensurate with that of the bacterial succinate respiration in vivo. The succinate dehydrogenase was similarly active in fumarate reduction with quinols. The highest activity was obtained with the most electronegative quinol. The fumarate reductase isolated from Wolinella succinogenes catalyzed succinate oxidation with quinones and fumarate reduction with the corresponding quinols at activities similar to those of the B. subtilis enzyme. Succinate oxidation by the lipophilic quinones, ubiquinone or vitamin K-1, was monitored as cytochrome c reduction using proteoliposomes containing succinate dehydrogenase together with the cytochrome bc1 complex. The activity with ubiquinone or vitamin K-1 was commensurate with the succinate respiratory activity of bacteria or of the bacterial membrane fraction. The results suggest that menaquinone is involved in the succinate respiration of B. subtilis, although its redox potential is unfavorable.
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PMID:Reactivity of the Bacillus subtilis succinate dehydrogenase complex with quinones. 165 27

The biochemical characteristics of the electron transfer chain are evaluated in purified non-synaptic ("free") mitochondria from the forebrain of 60-week-old rats weekly subjected to peroxidative stress (once, twice, or three times) by the electrophilic prooxidant 2-cyclohexene-1-one. The following parameters are evaluated: (a) content of respiratory components, namely ubiquinone, cytochrome b, cytochrome c1, cytochrome c; (b) specific activity of enzymes, namely citrate synthase, succinate dehydrogenase, rotenone-sensitive NADH: cytochrome c reductase, cytochrome oxidase; (c) concentration of reduced glutathione (GSH). Before the first peroxidative stress induction, the rats are administered for 8 weeks by intraperitoneal injection of vehicle, papaverine, delta-yohimbine, almitrine or hopanthenate. The rats are treated also during the week(s) before the second or third peroxidative stress. The cerebral peroxidative stress induces: (a) initially, a decrease in brain GSH concentration concomitant with a decrease in the mitochondrial activity of cytochrome oxidase of aa3-type (complex IV), without changes in ubiquinone and cytochrome b populations; (b) subsequently, an alteration in the transfer molecule cytochrome c and, finally, in rotenone-sensitive NADH-cytochrome c reductase (complex I) and succinate dehydrogenase (complex II). The selective sensitivity of the chain components to peroxidative stress is supported by the effects of the concomitant subchronic treatment with agents acting at different biochemical steps. In fact, almitrine sets limits to its effects at cytochrome c content and aa3-type cytochrome oxidase activity, while delta-yohimbine sets limits to its effects at the level of tricarboxylic acid cycle (citrate synthase) and/or of intermediary between tricarboxylic acid cycle and complex II (succinate dehydrogenase).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sequential damage in mitochondrial complexes by peroxidative stress. 166 94

Studies have demonstrated that accumulation of mitochondrial tocopheroxyl radical, the primary oxidation product of alpha-tocopherol, accompanies rapid consumption of tocopherol. Enzyme-linked electron flow lowers both the steady-state concentration of the radical and the consumption of tocopherol. Reduction of tocopheroxyl radical by a mitochondrial electron carrier(s) seems a likely mechanism of tocopherol recycling. Succinate-ubiquinone reductase (complex II) was incorporated into liposomes in the presence of tocopherol and ubiquinone-10. After inducing formation of tocopheroxyl radical, it was possible to show that reduced ubiquinone prevents radical accumulation and tocopherol consumption. There was no evidence of direct reduction of tocopheroxyl radical by succinate-reduced complex II. These reactions were also measured using ubiquinone-1 and alpha-C-6-chromanol (2,5,7,8-tetramethyl-2-(4'-methylpentyl)-6-chromanol) which are less hydrophobic analogues of ubiquinone-10 and alpha-tocopherol. Mitochondrial membranes were made deficient in ubiquinone but sufficient in alpha-tocopherol and were reconstituted with added quinone. With these membranes it was shown that mitochondrial enzyme-linked reduction of ubiquinone protects alpha-tocopherol from consumption, and there is a requirement for ubiquinone. This complements the observations made in liposomes and we propose that reduced mitochondrial ubiquinones have a role in alpha-tocopherol protection, presumably through efficient reduction of the tocopheroxyl radical.
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PMID:Succinate-ubiquinone reductase linked recycling of alpha-tocopherol in reconstituted systems and mitochondria: requirement for reduced ubiquinone. 172 50

Menaquinol-fumarate oxidoreductase of Escherichia coli is a four-subunit membrane-bound complex that catalyzes the final step in anaerobic respiration when fumarate is the terminal electron acceptor. The enzyme is structurally and catalytically similar to succinate dehydrogenase (succinate-ubiquinone oxidoreductase) from both procaryotes and eucaryotes. Both enzymes have been proposed to contain an essential cysteine residue at the active site based on studies with thiol-specific reagents. Chemical modification studies have also suggested roles for essential histidine and arginine residues in catalysis by succinate dehydrogenase. In the present study, a combination of site-directed mutagenesis and chemical modification techniques have been used to investigate the role(s) of the conserved histidine 232, cysteine 247, and arginine 248 residues of the flavorprotein subunit (FrdA) in active site function. A role for His-232 and Arg-248 of FrdA is shown by loss of both fumarate reductase and succino-oxidase activities following site-directed substitution of these particular amino acids. Evidence is also presented that suggests a second arginine residue may form part of the active site. Potential catalytic and substrate-binding roles for arginine are discussed. The effects of removing histidine-232 of FrdA are consistent with its proposed role as a general acid-base catalyst. The fact that succinate oxidation but not fumarate reduction was completely lost, however, might suggest that alternate proton donors substitute for His-232. The data confirm that cysteine 247 of FrdA is responsible for the N-ethylmaleimide sensitivity shown by fumarate reductase but is not required for catalytic activity or the tight-binding of oxalacetate, as previously thought.
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PMID:Identification of active site residues of Escherichia coli fumarate reductase by site-directed mutagenesis. 185 94

The activity of the mitochondrial glycerol phosphate dehydrogenase (EC 1.1.99.5), the enzyme unique to the glycerol phosphate hydrogen shuttle, was measured in normal human tissues and tumors and compared with the activity of succinate dehydrogenase, another enzyme that transfers electrons to ubiquinone at site II of the electron transport chain. Six of 7 insulinomas and 10 of 12 carcinoid tumors showed high glycerol phosphate dehydrogenase activity. The activity was also increased in 3 of 4 gastrinomas, 2 paraganglionomas, 1 of 4 thyroid nodules, and 1 parathyroid tumor. These tissues belong to the amine precursor uptake decarboxylation system. The activity of glycerol phosphate dehydrogenase was generally unremarkable in non-amine precursor uptake decarboxylation system tumors and in normal tissues studied. However, 1 of 2 breast carcinomas, 1 submandibular tumor, and 2 of 3 melanomas were enriched in glycerol phosphate dehydrogenase activity. In general, succinate dehydrogenase activity exceeded that of glycerol phosphate dehydrogenase in all tissues except some of the tissues in which glycerol phosphate dehydrogenase activity was high. Normal tissues, such as the pancreatic beta-cell, which aerobically metabolize glucose rapidly utilize the glycerol phosphate shuttle to oxidize the large amount of NADH formed from glucose metabolism in the cytosol. Whether this is the reason for the enriched activity of the glycerol phosphate dehydrogenase in certain amine precursor uptake decarboxylation system tumors is unknown.
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PMID:High activity of mitochondrial glycerol phosphate dehydrogenase in insulinomas and carcinoid and other tumors of the amine precursor uptake decarboxylation system. 197 16

The organophosphorus insecticide parathion depresses the phosphorylation efficiency of mitochondria as inferred from the decrease of RCR and ADP/O ratios. The transmembrane potential (delta psi) developed by energized mitochondria, and depolarization upon ADP addition are also decreased. Furthermore, repolarization is delayed and resumes at a slower rate. The inhibitory action of parathion on phosphorylation efficiency could be related with the following findings: (1) a direct effect on the succinate dehydrogenase-ubiquinone segment of the redox chain; (2) a direct action on the ATP synthetase complex; (3) partial inhibition of the phosphate transporter.
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PMID:Interference of parathion with mitochondrial bioenergetics. 215 6

Complex II (succinate-ubiquinone oxidoreductase) is an important enzyme complex of both the tricarboxylic acid cycle and of the aerobic respiratory chains of mitochondria in eukaryotic cell and prokaryotic organisms. In this study, the amino acid sequence of iron sulfur-subunit in human liver mitochondria was deduced from cDNA which was isolated by immunoscreening a human liver lambda gtll cDNA library. An isolated clone contains an open reading frame of 786 nucleotides and encodes a mature protein of 252 amino acids with a molecular weight of 28,804. The amino acid sequence was highly homologous with that of bovine heart (94.1%) which has been determined from the purified peptide and that of Escherichia coli sdh B product (50.8%). Striking sequence conservation was found around the three cysteine-rich clusters which have been thought to comprise the iron-sulfur centers of the enzyme. This is the first report on the cDNA sequence of mitochondrial complex II.
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PMID:Human complex II (succinate-ubiquinone oxidoreductase): cDNA cloning of iron sulfur (Ip) subunit of liver mitochondria. 230 93

The main target of local anaesthetics on nervous tissue is the sodium channel. Molecular biology and electrophysiology have shown different mechanisms of action on this sodium channel, which depend on the chemical structure and electrostatic charge of the local anaesthetic molecule. There are two main types of action, shown up on the isolated axon, a direct one on the sodium channel itself and an alteration in the lipids surrounding the channel. These effects have been shown on the isolated axon and explain the anaesthetic effect by an inhibition of the sodium current. Experimental studies have also shown the effects of local anaesthetics on different organelles within the cell, and so on intracellular metabolism. Mitochondrial energetic metabolism, and therefore ATP synthesis, is reduced by local anaesthetics at several levels. The respiratory enzyme chain is inhibited by small concentrations of local anaesthetic, especially NADH dehydrogenase and ubiquinone succinate dehydrogenase. Moreover, local anaesthetics increase the mitochondrial membrane permeability to protons, thus removing the moving force behind ATPase activity in ATP synthesis; this leads to a drastic fall in available energy. This effect is further increased by a direct inhibition of ATPase and ATP/ADP translocation. Other enzyme systems of other organelles are also disturbed by local anaesthetics, such as the endoplasmic reticular Ca++ ATPase, which is inhibited, so altering the calcium concentration within the cytosol. Local anaesthetics also inhibit lipolysis and glycogenesis. Receptors such as the acetylcholine receptors are blocked by local anaesthetics. The mechanism of action of these drugs on all these protein systems is two-fold: an alteration of protein structure, but also of the lipids surrounding them.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Molecular mechanism of action of local anesthetics]. 245 46

The effect of rhein on the oxygen consumption, oxidative phosphorylation, ATPase activity and redox state of electron carriers of rat liver mitochondria has been studied. Rhein inhibits ADP- and uncoupler-stimulated respiration on various NAD-linked substrates and succinate, but stimulates state 4 respiration of mitochondria respiring on succinate. Experiments on specific segments of the respiratory chain showed that rhein does not inhibit electron flow through cytochrome oxidase. Electron flow through site 2, the ubiquinone-cytochrome b-cytochrome c1 complex, was also unaffected by rhein, which failed to inhibit the oxidation of duroquinol. Rhein affects oxidative phosphorylation by inhibiting both electron transfer and ADP-driven H+ uptake. The inhibition of succinate oxidation by rhein was found to take place at a point between succinate and ubiquinone, perhaps at the level of succinic dehydrogenase. Spectroscopic evidence demonstrated that rhein induces a NAD(P)H oxidation in mitochondria respiring either on endogenous substrates or on glutamate + malate, and an inhibition of the cytochrome b reduction by succinate. These observations, together with other evidence, suggest that rhein inhibits electron transport in rat liver mitochondria at the dehydrogenase-coenzyme level, particularly when the electron carriers are in a relatively oxidized state and/or when the inner membrane-matrix compartment is in the condensed state.
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PMID:Sites of inhibition of mitochondrial electron transport by rhein. 252 79

A microbicidal system, mediated by neutrophil myeloperoxidase, inhibits succinate-dependent respiration in Escherichia coli at rates that correlate with loss of microbial viability. Succinate dehydrogenase, the initial enzyme of the succinate oxidase respiratory pathway, catalyzes the reduction of ubiquinone to ubiquinol, which is reoxidized by terminal oxidase complexes. The steady-state ratio of ubiquinol to total quinone (ubiquinol + ubiquinone) reflects the balance between dehydrogenase-dependent ubiquinone reduction and terminal oxidase-dependent ubiquinol oxidation. Myeloperoxidase had no effect on total quinone content of E. coli but altered the steady-state ratio of ubiquinol to total quinone. The ratio doubled for organisms incubated with the myeloperoxidase system for 10 min, suggesting decreased ubiquinol oxidase activity, which was confirmed by observation of a 50% decrease in oxidation of the ubiquinol analogue 2,3-dimethoxy-5-methyl-6-decyl-1,4-benzoquinol. Despite inhibition of ubiquinol oxidase, overall succinate oxidase activity remained unchanged, suggesting that succinate dehydrogenase activity was preserved and that the dehydrogenase was rate limiting. Microbial viability was unaffected by early changes in ubiquinol oxidase activity. Longer (60 min) exposure of E. coli to the myeloperoxidase system resulted in only modest further inhibition of the ubiquinol oxidase, but the ubiquinol to total quinone ratio fell to 0%, reflecting complete loss of succinate dehydrogenase activity. Succinate oxidase activity was abolished, and there was extensive loss of microbial viability. Early myeloperoxidase-mediated injury to ubiquinol oxidase appeared to be compensated for by higher steady-state levels of ubiquinol which sustained electron turnover by mass effect. Later myeloperoxidase-mediated injuries eliminated succinate-dependent ubiquinone reduction, through inhibition of succinate dehydrogenase, with loss of succinate oxidase activity, effects which were associated with, although not clearly causal for, microbicidal activity.
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PMID:Myeloperoxidase-mediated inhibition of microbial respiration: damage to Escherichia coli ubiquinol oxidase. 254 43


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