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)

Soluble succinate dehydrogenase prepared by butanol extraction reacts with N-ethylmaleimide according to first-order kinetics with respect to both remaining active enzyme and the inhibitor concentration. Binding of the sulfhydryl groups of the enzyme prevents its alkylation by N-ethylmaleimide and inhibition by oxaloacetate. A kinetic analysis of the inactivation of alkylating reagent in the presence of succinate or malonate suggests that N-ethylmaleimide acts as a site-directed inhibitor. The apparent first-order rate constant of alkylation increases between pH 5.8 and 7.8 indicating a pKa value for the enzyme sulfhydryl group equal to 7.0 at 22 degrees C in 50 mM Tris-sufate buffer. Certain anions (phosphate, citrate, maleate and acetate) decrease the reactivity of the enzyme towards the alkylating reagent. Succinate/phenazine methosulfate reductase activity measured in the presence of a saturating concentration of succinate shows the same pH-dependence as the alkylation rate by N-ethylmaleimide. The mechanism of the first step of succinate oxidation, including a nucleophilic attack of substrate by the active-site sulfhydryl group, is discussed.
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PMID:Reactivity of the sulfhydryl groups of soluble succinate dehydrogenase. 0 20

Spheroplasts that were osmotically stable in 0.2M Tris-HCl--0.02M EDTA were prepared from the autotrophically grown cells of Pseudomonas thermophila K-2. The spheroplasts possessed 90--95% of the hydrogenase activity of the whole cells. The half-life time of hydrogenase in the spheroplasts at 80 degrees C was 8.5 min. A spectrophotometric technique was developed for determining the membrane-bound hydrogenase in the presence of sulfhydryl compounds with methylene blue as electron acceptor. The maximal specific activity of hydrogenase in extracts prepared in the anaerobic conditions in the presence of dithiothreitol and Mg2+ and Mn2+ ions was 10 +/- 3 units per 1 mg of protein, which closely corresponded with the activity of hydrogenase in the whole cells. Almost all activity of hydrogenase assayed with methylene blue was localized in the membrane fraction. The activity of soluble NAD-specific hydrogenase was not detected. Large particles located in 60-70% sucrose had the highest hydrogenase activity upon fractionation in a continuous sucrose concentration gradient. The second, lower peak of the hydrogenase activity was detected in fractions of 40--50% sucrose. As was found by electron microscopy, the size of membrane vesicles with the hydrogenase activity varied within the range of 68--156 nm. The membrane preparations possessed the activity of NADH-dehydrogenase, NADH-oxidase and succinate dehydrogenase as well.
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PMID:[Localization of hydrogenase in the cells of the thermophilic hydrogen bacterium, Pseudomonas thermophila]. 21 85

The involvement of a histidine residue of the membrane-anchoring protein (QPs) fraction in reconstitution of succinate dehydrogenase to form succinate-ubiquinone reductase is studied by using a histidine-modifying reagent, diethylpyrocarbonate (DEPC). A maximum inactivation of 80% of reconstitutive activity is obtained when QPs is treated with 1 mM DEPC at 0 degrees C for 30 min in 50 mM Tris-HCl (pH 7.0). DEPC also inactivates about 85% of intact succinate-ubiquinone reductase. The inactivation of succinate-ubiquinone reductase by DEPC is a result of the modification of essential histidine residues of succinate dehydrogenase. The inactivation is not a result of the modification of the histidine residue in QPs which is essential for interaction with succinate dehydrogenase because the QPs dissociated from the inactivated succinate-ubiquinone reductase is active in reconstitution with active succinate-dehydrogenase. Apparently, the essential histidine in QPs is shielded by succinate dehydrogenase and thus inaccessible to DEPC modification in succinate-ubiquinone reductase. The involvement of a histidine residue of QPs in interaction with succinate dehydrogenase is further evident by the presence of 553 nm shoulder on the alpha-absorption peak of reduced cytochrome b-560 (a characteristic of physical association of QPs with succinate dehydrogenase) in the DEPC-inactivated succinate-ubiquinone reductase. This shoulder disappears from a mixture of succinate dehydrogenase and DEPC-treated QPs when reduced with dithionite. About one histidine residue per molecule of QPs is modified in the DEPC-treated sample, suggesting that only one histidine residue is essential for interaction with succinate dehydrogenase. This essential histidine group is located in the smaller subunit (Mr 13,000) of QPs.
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PMID:Involvement of a histidine residue in the interaction between membrane-anchoring protein (QPs) and succinate dehydrogenase in mitochondrial succinate-ubiquinone reductase. 199 11

Analytical subcellular fractionation of tissue whole homogenates and microanalysis of organelle marker enzymes were used to study the activity and subcellular localization of enzymes implicated in HCO3 secretion in rat duodenal and gastric antral mucosae. The following organelles, characterized by their marker enzymes, were located in the density gradients: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), peroxisomes (catalase), mitochondria (succinate dehydrogenase), endoplasmic reticulum (Tris-resistant alpha-glucosidase), lysosomes (N-beta-acetylglucosaminidase), and brush-border membrane (Zn2+-resistant alpha-glucosidase and alkaline phosphatase). Compared with gastric antrum, rat duodenal mucosa contained over twice the activity of HCO3-ATPase and of Na+-K+-ATPase but less than one-tenth the activity of carbonic anhydrase. Duodenal HCO3-ATPase activity was observed in both mitochondrial and brush-border membrane fractions, whereas antral HCO3-ATPase activity was confined to mitochondria. Na+-K+-ATPase activity was found largely in the basolateral membrane (duodenum) and plasma membrane (antrum). In both tissues carbonic anhydrase activity was localized to the cytosolic fraction. These observations offer further evidence that differing biochemical mechanisms underlie HCO3 secretion by gastric and duodenal epithelia.
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PMID:Activities and subcellular localizations of enzymes implicated in gastroduodenal bicarbonate secretion. 608 73

The possible role of Mg2+-HCO3-ATPase, carbonic anhydrase and several other enzymes in rat intestinal mucosa as mediators of the action of aldosterone has been examined. The small-intestinal tract was cut into seven segments, 15 cm each in length and the mucosa was scraped off, homogenized in 50 mM D-mannitol-2 mM Tris-HCl buffer (pH 7.1), differentially fractionated and a crude brush border was obtained. The mucosa from the colon and rectum was combined and used as the large-intestinal sample. Five days after the adrenalectomy, activities of brush border Mg2+-HCO3-ATPase and supernatant carbonic anhydrase from the upper small intestine decreased to about 60 and 40% of normal values, respectively. Activities of Na+-K+-ATPase, beta-glycerophosphatase and succinate dehydrogenase were all decreased. Two and 4 h after i.p. injection of aldosterone (40 micrograms/kg) to adrenalectomized rats, all enzyme activities increased except for Na+-K+-ATPase in the upper small intestine. In contrast, Mg2+-HCO-3-ATPase and carbonic anhydrase activities were unchanged 3 h after i.p. injection of dexamethasone (200 micrograms and 1 mg/kg). The activation of both Mg2+-HCO3-ATPase and carbonic anhydrase by a single injection of aldosterone was blocked by pretreatment with cycloheximide (1 mg/kg). These results suggest that aldosterone may induce the synthesis of enzyme proteins in the intestinal mucosa.
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PMID:Brush border Mg2+-HCO-3-ATPase, supernatant carbonic anhydrase and other enzyme activities isolated from rat intestinal mucosa: effect of adrenalectomy and aldosterone administration. 613 8

Through a methodological evaluation, reliable histochemical and biochemical methods for succinate dehydrogenase activity in cultured human skin fibroblasts and amniotic fluid cells were developed. The histochemical method includes a cleaning of the cultured cells in 1 mM malonate in 0.9% NaCl, air-drying and fixation in acetone (5 min at -20 degrees C), coating of cells with CoQ10 (0.2 mg/ml in ether/acetone) and incubation for 1 h at 37 degrees C in 50 mM succinate and 0.5 mg/ml Nitro BT in 200 mM phosphate buffer, pH 7.6 PMS as an intermediate electron carrier was found inferior to exogenous CoQ10. Both types of cells exhibit equal activity. In the biochemical method homogenizing was performed in 50 mM Tris-HCl buffer, pH 7.5, and 200 mM sucrose. The standard incubation was 2.0 mM INT and 10 mM succinate in 10 mM Tris-HCl buffer, pH 7.5 for 1 h at 37 degrees C. The apparent Km values for INT and succinate were estimated to 0.39 mM and 0.13 mM, respectively, while I0.5 for malonate was 0.46 mM. Activity in amniotic fluid cells was 18.1 pkat/mg protein and in human skin fibroblasts 20.3 pkat/mg protein. Specificity of the methods was tested by use of a Chinese hamster fibroblast strain B9 known to be succinate dehydrogenase deficient in addition to various control experiments. Congruent results were obtained with the two methods.
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PMID:Succinate dehydrogenase activity in cultured human skin fibroblasts and amniotic fluid cells. A methodological study. 687 23

Photosystem II (PSII) complexes, isolated from spinach and the thermophilic cyanobacterium Synechococcus elongatus, were characterized by electron microscopy and single-particle image-averaging analyses. Oxygen-evolving core complexes from spinach and Synechococcus having molecular masses of about 450 kDa and dimensions of approximately 17.2 x 9.7 nm showed twofold symmetry indicative of a dimeric organization. Confirmation of this came from image analysis of oxygen-evolving monomeric cores of PSII isolated from spinach and Synechococcus having a mass of approximately 240 kDa. Washing with Tris at pH 8.0 and analysis of side-view projections indicated the possible position of the 33-kDa extrinsic manganese-stabilizing protein. A larger complex was isolated that contained the light-harvesting complex II (LHC-II) and other chlorophyll a/b-binding proteins, CP29, CP26, and CP24. This LHC-II-PSII complex had a mass of about 700 kDa, and electron microscopy revealed it also to be a dimer having dimensions of about 26.8 and 12.3 nm. From comparison with the dimeric core complex, it was deduced that the latter is located in the center of the larger particle, with additional peripheral regions accommodating the chlorophyll a/b-binding proteins. It is suggested that two LHC-II trimers are present in each dimeric LHC-II-PSII complex and that each trimer is linked to the reaction center core complex by CP24, CP26, and CP29. The results also suggest that PSII may exist as a dimer in vivo.
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PMID:Supramolecular structure of the photosystem II complex from green plants and cyanobacteria. 781 11

Peroxynitrite anion, the reaction product of superoxide and nitric oxide, is a potent biological oxidant, which inactivates mammalian heart mitochondrial NADH-coenzyme Q reductase (complex I), succinate dehydrogenase (complex II), and ATPase, without affecting cytochrome c oxidase (complex IV). In this paper, we evaluated the effect of peroxynitrite on mitochondrial membrane integrity and permeability under low calcium concentration. Phosphate buffer was used in most of our experiments since Hepes, Tris, mannitol, and sucrose were found to inhibit the oxidative chemistry of peroxynitrite. Peroxynitrite (0.1-1.0 mM) caused a dose-dependent decrease in the ability of mitochondria to build up a membrane potential when N,N,N',N'-tetramethyl-p-phenylenediamine/ascorbate were used as substrate. Elimination of the membrane potential was accompanied by penetration of the osmotic support (KCl/NaCl) into the matrix as judged by the parallel occurrence of mitochondrial swelling. This swelling was partially inhibited by dithiothreitol (DTT) or butylated hydroxytoluene (BHT) and was insensitive to ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid, ADP, and cyclosporin A. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of solubilized membrane proteins indicated that alterations in membrane permeability were associated with the production of protein aggregates due to membrane protein thiol cross-linking. The protective effect of DTT on both mitochondrial swelling and protein polymerization suggests the involvement of disulfide bonds in the membrane permeabilization process. In addition, the increase in thiobarbituric acid-reactive substances and the partial inhibitory effect of BHT indicate the occurrence of lipid peroxidation. These results support the idea that under our experimental conditions peroxynitrite causes mitochondrial structural and functional alterations by Ca2+-independent mechanisms through lipid peroxidation and protein sulfhydryl oxidation.
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PMID:Ca2+-independent permeabilization of the inner mitochondrial membrane by peroxynitrite is mediated by membrane protein thiol cross-linking and lipid peroxidation. 930 96

We report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of seven trimeric light-harvesting complex II proteins. The complex was readily observed in partially-solubilized Tris-washed photosystem II membranes from spinach but was also found to occur, with a low frequency, in oxygen-evolving photosystem II membranes. The structure reveals six peripheral trimers with the same rotational orientation and a central trimer with the opposite orientation. We conclude that the heptamer represents a naturally occurring aggregation state of part of the light-harvesting complex II trimers in the thylakoid membranes.
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PMID:Heptameric association of light-harvesting complex II trimers in partially solubilized photosystem II membranes. 1033 34

In this study, proteomes of two pathogenic Leptospira spp., namely L. interrogans, serogroup Icterohaemorrhagiae, serovar Copenhageni and L. borgpetersenii, serogroup Tarassovi, serovar Tarassovi, were revealed by using two dimensional gel electrophoresis (2DE)-based-proteomics. Bacterial cells were disrupted in a lysis buffer containing 30 mM Tris, 2 M thiourea, 7 M urea, 4% CHAPS, 2% IPG buffer pH 3-10 and protease inhibitors and then subjected to sonication in order to solubilize as much as possible the bacterial proteins. The 2DE-separated components of both Leptospira homogenates were blotted individually onto membranes and antigenic components (immunomes) were revealed by probing the blots with immune serum of a mouse readily immunized with the homogenate of L. interrogans, serogroup Icterohaemorrhagiae, serovar Copenhageni. The immunogenic proteins of the two pathogenic Leptospira spp. could be grouped into 10 groups. These are: 1) proteins involved in the bacterial transcription and translation including beta subunit transcription anti-termination protein of DNA polymerase III, elongation factors Tu and Ts, and tRNA (guanine-N1)-methyltransferase; 2) proteins functioning as enzymes for metabolisms and nutrient acquisition including acetyl-Co-A acetyltransferase, putative glutamine synthetase, glyceraldehyde-3-phospahte dehydrogenase, NifU-like protein, 3-oxoacyl-(acyl-carrier-protein) reductase, oxidoreductase, sphingomyelinase C precursor, spermidine synthase, beta subunit of succinyl-CoA synthetase, and succinate dehydrogenase iron-sulfur subunit; 3) proteins/enzymes necessary for energy and electron transfer, i.e. electron transfer flavoprotein, and proton-translocating transhydrogenase; 4) enzymes for degradation of misfolded proteins, i.e. ATP-dependent Clp protease; 5) molecular chaperone, i.e. 60 kDa chaperonin; 6) signal transduction system, i.e. response regulator; 7) protein involved in immune evasion in host, i.e. peroxiredoxin; 8) cell structure proteins including MreB (cytoskeletal) and flagellin/ periplasmic flagellin; 9) lipoproteins/outer membrane proteins: LipL32, LipL41, LipL45 and OmpL1; and 10) various hypothetical proteins. Many immunogenic proteins are common to both Leptospira spp. These proteins not only are the diagnostic targets but also have potential as candidates of a broad spectrum leptospirosis vaccine especially the surface exposed components which should be vulnerable to the host immune effector factors.
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PMID:Proteome and immunome of pathogenic Leptospira spp. revealed by 2DE and 2DE-immunoblotting with immune serum. 1789 22


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