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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)

In an in vitro study with rat liver, ammonium meta vanadate (NH4VO3) was found to inhibit microsomal ketamine N-demethylation, lipid peroxidation, and hydrogen peroxide formation; to have no effects on 4-methylaminoantipyrine N-demethylation and on glucuronyltransferase I activity, and to enhance glucuronyltransferase II. Mitochondrial succinate dehydrogenase and cytochrome c reductase were inhibited but cytochrome oxidase activity was enhanced by ammonium vanadate. Ammonium meta vanadate increased malate dehydrogenase activity but had no effect on glutamate, lactate, glycerophosphate, isocitrate, glucose-6-phosphate, and 6-phosphogluconate dehydrogenases.
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PMID:Action of ammonium meta vanadate on hepatic enzymes in vitro. 660 35

The equilibrium and rate constants for interaction of the reduced and oxidized membrane-bound succinate dehydrogenase (EC 1.3.99.1) with oxaloacetate were determined. The 10-fold decrease in the oxaloacetate affinity for the reduced enzyme was shown to be due to the 10-fold increase of the enzyme-inhibitor complex dissociation rate, which occurs upon its reduction. The rate of dissociation induced by succinate is 10 times higher than that induced by malonate in the submitochondrial particles, being equal in the soluble enzyme preparations. The rates of dissociation induced by malonate excess, or by the enzyme irreversibly utilizing oxaloacetate (transaminase in the presence of glutamate) are also equal. The data obtained suggest that succinate dehydrogenase interaction with succinate and oxaloacetate results from the competition for a single dicarboxylate-specific site. In submitochondrial particles all succinate dehydrogenase molecules are in redox equilibrium provided for by endogenous ubiquinone. No electronic equilibrium between the individual enzyme molecules exists, when succinate dehydrogenase is solubilized.
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PMID:[Interaction of succinate dehydrogenase and oxaloacetate]. 673 63

The effects of membrane composition on the sensitivity of membrane functions to ethanol in Escherichia coli have been investigated. The addition of ethanol (0.67M) in vitro did not cause appreciable inhibition of NADH oxidase, D-lactate oxidase or ATPase but caused an 11% to 30% inhibition of succinic dehydrogenase, glutamate uptake, proline uptake and 1ac permease. Although the sensitivities of some of these membrane functions to ethanol varied with membrane composition, none correlated with the changes in sensitivity to killing by ethanol. In contrast, leucine transport was resistant to ethanol (0.67M) in control cells and in cells enriched in vaccenic acid, but was inhibited by 25% in cells grown in palmitic acid. The release of nucleotides was examined as a comparative measure of cellular permeability. Ethanol increased nucleotide leakage. Leakage was reduced in cells grown in vaccenic acid and enhanced in cells enriched in palmitic acid. The addition of MgSO4 (10mM) reduced nucleotide leakage and enhanced survival. Based upon these results, metabolite leakage was proposed as the primary event associated with bacterial inactivation in buffered solutions of ethanol. The increase in acyl chain length is proposed as the beneficial aspect of vaccenic acid incorporation rather than the increase in membrane unsaturation.
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PMID:Effects of fatty acid composition on the sensitivity of membrane functions to ethanol in Escherichia coli. 675 94

Mechanisms of subcellular dysfunction of the liver in sepsis are still obscure. The present study investigates changes in oxidative phosphorylative activity and calcium-induced respiration of rat liver mitochondria following live Escherichia coli injection (E coli, Serotype: 0--18. A 1.25--1.5 X 10(9)/100 gm body wt inoculum of E coli bacteria was injected via the tail vein, causing a 100% mortality rate within 24 hours after injection. In order to determine alteration of liver mitochondrial membrane permeability, serum ornithine carbamoyltransferase activity was measured following E coli injection. This activity increased ten to 100-fold over that of controls with time following injection. However, the yield of liver mitochondria from treated rats, estimated by the amount of collected mitochondrial protein and the recovery rate of succinate dehydrogenase activity in the final mitochondrial suspensions, was not significantly different from that of controls. Mitochondrial oxidative phosphorylative activity measured using glutamate as a substrate was enhanced throughout all period to death (P less than 0.01 at three and six hours, P less than 0.05 in the fatal stage) and was associated with concomitant increases in respiratory control ratios. Similar results were obtained using beta-hydroxybutyrate as a substrate. This enhancement was accompanied by an increase in 2-4-dinitrophenol-stimulated ATPase activity (160% at three hours and 130% in the fatal stage). Calcium-induced stimulation of mitochondrial respiration as well as initial calcium uptake rate linked to respiration, using glutamate as a substrate, were higher in liver mitochondria from rats with E coli treatment than in those of controls throughout all periods (P less than 0.01 or less). These results suggest the coexistence of hyperfunctioning as well as deteriorated mitochondria following lethal treatment with E coli.
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PMID:A study of oxidative phosphorylative activity and calcium-induced respiration of rat liver mitochondria following living Escherichia coli injection. 675 40

Administration of physiologically low doses of bicarbonate into rats caused an inhibition of oxidative phosphorylation and a transitory decrease in ATP content in liver mitochondria; at the same time, concentrations of malate and glutamate were unaltered and those of pyruvate and phosphoenolpyruvate were decreased. Insulin removed the bicarbonate effect on mitochondrial functions but affected only slightly the distribution of metabolites. Bicarbonate appears to activate pyruvate carboxylase and to inhibit succinate dehydrogenase as well as the operation of tricarboxylic acid cycle due to accumulation of oxaloacetate. The effect of insulin mimics acceleration of decarboxylation reactions in mitochondria.
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PMID:[Effect of bicarbonate and insulin on energy metabolism in the mitochondria of rat liver]. 676 May 41

14C-labeled bicarbonate was incorporated into trichloroacetic acid-insoluble material by cell suspensions of A. viscosus strain M100 and also into the four-carbon fermentation product, succinate, but not into the three-carbon fermentation product, lactate. The initial step in the conversion of 14C-labeled bicarbonate into both trichloroacetic acid-insoluble material and succinate was catalyzed by the enzyme phosphoenolypyruvate carboxylase, which served to convert the glycolytic intermediate, phosphoenolpyruvate, and bicarbonate to the four-carbon compound, oxalacetate. The metabolic fate of oxalacetate was its conversion to either trichloroacetic acid-insoluble material or succinate. One pathway by which oxalacetate may be metabolized into acid-insoluble material is via its conversion to the biosynthetic precursor aspartate by the action of glutamate aspartate aminotransferase. One source of the alpha-amino group of aspartate was the ammonium ion, which could be incorporated into glutamate, the substrate of the glutamate aspartate aminotransferase reaction, by the action of a reduced nicotinamide adenine dinucleotide phosphate-dependent glutamate dehydrogenase whose reducing equivalents could be derived from the nicotinamide adenine dinucleotide phosphate-dependent oxidative reactions of the hexose monophosphate pathway catalyzed by glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Alternatively, oxalacetate was converted to the fermentation product, succinate, through the sequential action of malate dehydrogenase, fumarase, and succinic dehydrogenase. The resolution and partial purification of phosphoenolpyruvate carboxylase, glutamate aspartate aminotransferase, glutamate dehydrogenase, malate dehydrogenase, fumarase, and succinic dehydrogenase are also reported.
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PMID:Carbon dioxide metabolism by Actinomyces viscosus: pathways for succinate and aspartate production. 676 22

In experiments on 6 and 16 days old rats cytophotometric studies have been made of histochemical reactions for succinate, lactate and glutamate dehydrogenases, alpha-glycerophosphate dehydrogenase and glucose-6-phosphate dehydrogenase in the supraoptic nucleus, paraventricular hypothalamic nucleus and the posterior hypophysis. It was found that heterochronous development of the neurones in the supraoptic and paraventricular nuclei, as well as the development of their axons in the posterior hypothalamus depend on the rate of maturation of the enzymic systems in postnatal life. In consolidation of the unique structure of the hypothalamic neurosecretory system, the key role is played by afferent influences, succinic dehydrogenase being involved into their realization. The data obtained indicate the importance of heterochronous development of the enzymic activities in the formation of bifunctional properties of neurosecretory hypothalamic neurones and reveal the primary development of neurotransmittery function as compared to the excretory one.
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PMID:[Quantitative histoenzymatic analysis of the hypothalamic neurosecretory system in rat ontogeny]. 683 89

1. The factors affecting the pathway of glutamate oxidation were studied in isolated rat-liver mitochondria in incubations of 2-3 min. 2. It was found that bicarbonate at a physiological concentration has a profound effect on the pathway of glutamate oxidation. Ammonia formation via glutamate dehydrogenase is stimulated by bicarbonate [from 5.48 +/- 0.29 (n = 10) to 9.57 +/- 0.73 (n = 8) nmol X min-1 X mg protein-1], whereas aspartate formation via the transamination pathway is inhibited [from 38.41 +/- 2.24 (n = 9) to 24.56 +/- 3.28 (n = 6) nmol X min-1 X mg protein-1]. 3. Bicarbonate has no effect on the rate of transport of glutamate via the glutamate-hydroxyl translocator. 4. The interaction of bicarbonate with the pathway of glutamate oxidation occurs primarily at the level of succinate dehydrogenase, due to competitive inhibition of the enzyme by bicarbonate. 5. Inhibition by bicarbonate of the transamination pathway leads to a decrease in intramitochondrial 2-oxoglutarate, so that the deamination pathway is stimulated. 6. Using an equation which describes flux through glutamate dehydrogenase kinetically, it could be shown that the bicarbonate-induced decrease in intramitochondrial 2-oxoglutarate quantitatively accounts for the enhanced rate of deamination. 7. It is concluded that in the intact liver flux through glutamate dehydrogenase is sufficient to account for the ammonia formation required for urea synthesis from substrates such as alanine.
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PMID:Bicarbonate and the pathway of glutamate oxidation in isolated rat-liver mitochondria. 685 31

1) In the present study the influence of sucrose and mannitol-based isolation media on the degree of functional preservation of rat liver mitochondria has been investigated. Apparently intact mitochondria conventionally prepared with a 0.3M sucrose medium displayed significantly lower rates of state-3 respiration, pyruvate carboxylation, ATP hydrolysis and thiol group production than mitochondria prepared from the same livers with mannitol. 2) Extracts from the latter, furthermore, showed a significantly higher activity of succinate dehydrogenase activity, whereas no difference in glutamate dehydrogenase activity was demonstrable. 3) The low activities apparent with the sucrose medium could be brought to the level of the mannitol medium by the addition of potassium phosphate (4mM). A similar effect was exerted by K2SO4, whereas KCl and the respective sodium salts were significantly less effective. 4) Sucrose-prepared mitochondria display decreased contents of metabolites such as ATP, glutamate, citrate and malate. 5) Comparative studies with a variety of carbohydrates indicated that isolation media based on disaccharides are inferior to those based on monosaccharides in the preparation of functionally intact mitochondria from rat liver. 6) The results reported herein appear to be of general interest as sucrose-prepared mitochondria have been employed in the past in a great number of studies and are still widely used at present.
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PMID:Influence of isolation media on the preservation of mitochondrial functions. 686 77

The minimum requirement for unsaturated fatty acids was investigated in E. coli using a mutant impaired in the synthesis of vaccenic acid. Exogenously supplied palmitic acid was incorporated by this mutant which led to a reduction in the proportion of cellular unsaturated fatty acids. Growth was impaired as the level of saturated fatty acids approached 76% at 37 degree C and 60% at 30 degree C. The basis of this growth inhibition was investigated. Most transport systems and enzymes examined remained active in palmitate-grown cells although the specific activities of glutamate uptake and succinic dehydrogenase were depressed 50%. Fluorescent probes of membrane organization indicated that fluidity decreased with palmitate incorporation. Temperature scans with parinaric acid indicated that rigid lipid domains exist in palmitate-grown cells at their respective growth temperature. Freeze-fracture electron microscopy confirmed the presence of phase separations (particle-free areas) in palmitate-grown cells held at their growth temperature prior to quenching. The extent of this separation into particle-free and particle-enriched domains was equivalent to that induced by a shift to 0 degree C in control cells. The incorporation of palmitate increased nucleotide leakage over threefold. The cytoplasmic enzyme beta-galactosidase was released into the surrounding medium as the concentration of unsaturated fatty acid approached the minimum for a particular growth temperature. Lysis was observed as a decrease in turbidity when cells which had been grown with palmitate were shifted a lower growth temperature. From these results we propose that leakage and partial lysis are the major factors contributing to the apparent decrease in growth rate caused by the excessive incorporation of palmitate. Further, we propose that membrane integrity may determine the minimum requirement for unsaturated fatty acids in E. coli rather than a specific effect on membrane transport and/or membrane-bound enzymes.
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PMID:Unsaturated fatty acid requirement in Escherichia coli: mechanism of palmitate-induced inhibition of growth of strain WN1. 703 75


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