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:2.3.3.1 (citrate synthase)
4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activities in rabbit heart mitochondria of acetoacetyl-CoA-thyolase, pyruvate dehydrogenase, acetyl CoA-synthetase, citrate synthase and acetyl carnitine transferase were compared. These enzymes participate in formation and utilization of acetyl-CoA. The acetoacetyl-CoA-thyolase and acetyl CoA-synthetase were shown to possess the more distinct capacity in vitro to form acetyl CoA. The co-enzyme was most efficiently utilized under these experimental conditions by the citrate synthase. The enzymes studied were localized within the mitochondria fraction in both the subfractions of soluble and membrane-bound proteins. In myocarditis a distinct decrease in activities of the acetoacetyl-CoA-thyolase and citrate synthase was observed.
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PMID:[The correlation between activity of enzymes participating in the formation and utilization of acetyl CoA in rabbit heart mitochondria in myocarditis and normal state]. 0 26

The triarylmethane derivative Victoria Blue-BO (VB-BO) and the chalcogenapyrylium (CP) dyes have potential for use in photochemotherapy, because they are taken up by the mitochondria of malignant cells and cause cell death. To clarify the mechanism of cell killing we examined the phototoxic effects of VB-BO and a series of three CP dyes on bioenergetic function in isolated rat liver mitochondria. Without photoirradiation, and irrespective of the respiratory substrate used, each of the compounds tested induced some uncoupling of oxidative phosphorylation. Visible irradiation of VB-BO produced an inhibition of mitochondrial respiration when glutamate plus malate, but not succinate, was used as the respiratory substrate. With photoirradiation VB-BO was also shown to inhibit rotenone-sensitive NADH-cytochrome c reductase activity, but it had no effect on succinate-cytochrome c reductase activity. These data indicate that photoactivation of VB-BO produces selective inhibition of mitochondrial respiratory complex I. Photoirradiation of the CP dyes inhibited both complex I and complex II initiated respiratory activity. With photoirradiation, the CP dyes also inhibited both NADH- and succinate-cytochrome c reductase activities, as well as other membrane-bound enzymes, cytochrome c oxidase and succinate dehydrogenase, but not the mitochondrial matrix enzyme, citrate synthetase, or the cytosolic enzyme, lactate dehydrogenase. alpha-Tocopherol protected bioenergetic activities against CP dye photodamage. These results suggest that mitochondrial photosensitization by CP compounds is mediated by the production of membrane-damaging singlet oxygen which causes nonspecific damage to membranes and membrane-bound enzymes.
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PMID:Mitochondrial toxicity of cationic photosensitizers for photochemotherapy. 217 36

The influence of storage of bovine and porcine muscle at -20 degrees C for 12 months and of thawing on the total extractable activity and subcellular distribution (activities in the supernatant of a phosphate buffer extract and in the press juice of the thawed tissue) of the mitochondrial enzymes lipoamide dehydrogenase (LIPDH), citrate synthase (CS) and beta-hydroxyacyl-CoA-dehydrogenase (HADH) was studied. The total activity of LIPDH decreased during frozen storage whereas the activities of CS and HADH did not change appreciably. From the increase of CS and HADH activities in the muscle press juice it was concluded that--additionally to the effect of freezing and thawing itself--frozen storage results in further damage to the inner membrane of muscle mitochondria, which may be recognized from the increased release of membrane-bound enzymes. In this respect porcine muscle mitochondria seem to be more sensitive than bovine muscle mitochondria.
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PMID:[Lipoamide dehydrogenase, citrate synthase, and beta-hydroxyacyl-CoA-dehydrogenase in skeletal muscles. X. The influence of frozen storage of bovine and porcine muscle on activity and subcellular distribution]. 384 Sep 39

Frozen storage at -20 degrees C for three months and thawing of muscles from sheep, hare and deer, and of the breast and leg muscles from chicken and duck did not result in significant changes in the extractable total activities of the mitochondrial enzymes citrate synthase and beta-hydroxyacyl-CoA-dehydrogenase; however there was a decrease in the total activity of lipoamide dehydrogenase except in the chicken leg muscle, where such a decrease did not occur. From the increase in the activities of the three enzymes in the muscle press juice it was concluded that - additionally to the effect of freezing and thawing itself - frozen storage results in further damage to the inner membrane of muscle mitochondria which is signalled by the release of membrane-bound enzymes. Chicken muscle mitochondria seem to be more stable against frozen storage of the tissue than the mitochondria in the muscles of the other species studied (including bovine and porcine muscle).
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PMID:[Lipoamide dehydrogenase, citrate synthase and beta-hydroxyacyl-CoA-dehydrogenase of skeletal muscle. 9. Influence of frozen storage of musculature of sheep, game and poultry on activity and subcellular distribution]. 384 Sep 40

Microbodies from rat liver and a variety of plant tissues were osmotically shocked and subsequently centrifuged at 40,000 g for 30 min to yield supernatant and pellet fractions. From rat liver microbodies, all of the uricase activity but little glycolate oxidase or catalase activity were recovered in the pellet, which probably contained the crystalline cores as many other reports had shown. All the measured enzymes in spinach leaf microbodies were solubilized. With microbodies from potato tuber, further sucrose gradient centrifugation of the pellet yielded a fraction at density 1.28 g/cm(3) which, presumably representing the crystalline cores, contained 7% of the total catalase activity but no uricase or glycolate oxidase activity. Using microbodies from castor bean endosperm (glyoxysomes), 50-60% of the malate dehydrogenase, fatty acyl CoA dehydrogenase, and crotonase and 90% of the malate synthetase and citrate synthetase were recovered in the pellet, which also contained 96% of the radioactivity when lecithin in the glyoxysomal membrane had been labeled by previous treatment of the tissue with [(14)C]choline. When the labeled pellet was centrifuged to equilibrium on a sucrose gradient, all the radioactivity, protein, and enzyme activities were recovered together at peak density 1.21-1.22 g/cm(3), whereas the original glyoxysomes appeared at density 1.24 g/cm(3). Electron microscopy showed that the fraction at 1.21-1.22 g/cm(3) was comprised of intact glyoxysomal membranes. All of the membrane-bound enzymes were stripped off with 0.15 M KCl, leaving the "ghosts" still intact as revealed by electron microscopy and sucrose gradient centrifugation. It is concluded that the crystalline cores of plant microbodies contain no uricase and are not particularly enriched with catalase. Some of the enzymes in glyoxysomes are associated with the membranes and this probably has functional significance.
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PMID:Localization of enzymes within microbodies. 472 5

The structural changes accompanying digitonin-induced release of enzymes and metabolites from isolated hepatocytes have been studied by scanning and transmission electron microscopy. In the initial phase, characterized by total release of the cytosolic marker enzyme, lactate dehydrogenase, the plasma membrane was immediately damaged, rapidly followed by extensive damage to the endoplasmic reticulum. The shape of the cell, however, was maintained, and the mitochondria and nucleus remained tightly held together by the cytoskeleton. Mitochondria remained intact initially, whereas the cytosol became less electron dense and the nuclear chromatin was more dispersed. An intermediate phase was characterized by total release of adenylate kinase and most of the glucose-6-phosphatase, marker enzymes for the mitochondrial intermembrane space and the endoplasmic reticulum, respectively. The outer mitochondrial membrane was ruptured, but mitochondria maintained their normal matrix electron density. In the final phase, characterized by the beginning of citrate synthase release from the mitochondrial matrix space, the mitochondria became swollen, and only the nucleus, inner and outer mitochondrial membranes, and the cytoskeleton could be clearly distinguished. Although the plasma membrane could not be readily discerned in electron micrographs after the initial phase, the plasma membrane marker enzyme 5'-nucleotidase remained associated with digitonin-treated hepatocytes. Acetyl-CoA carboxylase was released much more slowly than lactate dehydrogenase, indicating some severe restriction on its release. The release of acetyl-CoA carboxylase closely paralleled the release of glucose-6-phosphatase. The controlled exposure of hepatocytes to digitonin, therefore, leads to the sequential release of soluble, compartmentalized cellular components and some membrane-bound components, but the mitochondrial membrane, cytoskeleton and the nucleoskeleton survive even long-term digitonin treatment.
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PMID:Structural changes of isolated hepatocytes during treatment with digitonin. 614 31

Chronic exposure of E. coli to ethanol during growth resulted in major changes in lipid composition. These ethanol-induced changes, a decrease in the proportion of saturated fatty acids, are similar to those which occur following a shift to lower temperature. Products of ethanol metabolism such as acetaldehyde and acetate caused the opposite changes in fatty acid composition. In vivo studies using mutants blocked in lipid synthesis indicated that saturated fatty acid synthesis was the primary target leading to changes in bulk lipid fatty acid composition. This was confirmed in vitro and condensing enzyme II was identified as the probable site of ethanol inhibition. The acute affects of ethanol on the function of two membrane-bound enzymes, Mg++ATPase and lac permease were also examined. In both cases, cells grown in the presence of ethanol. In time-course studies, permease function was restored concurrently with changes in lipid composition. Mutants were isolated which were able to grow in the presence of high levels of ethanol. These mutants displayed exaggerated changes in lipid composition providing evidence that alcohol-resistance and fatty acid changes are related.
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PMID:Reversible effects of ethanol on E. coli. 644 36

The basal- and allylisopropylacetamide-induced activities of the first enzyme of heme biosynthesis, delta-aminolevulinic acid synthase (ALAS) were measured in hepatic mitochondria and cytosol of young, adult, and aged Fisher 344 rats. The total cellular ALAS activity induced by allylisopropylacetamide decreased 67% with age. The specific activity of mitochondrial ALAS in normal and induced animals decreased with aging when assayed in whole or broken mitochondria. The levels of ALAS which accumulated in the cytosol after allylisopropylacetamide administration were proportionally greater in both the young and senescent than in the mature animals. During aging, no evidence for a fragile population of mitochondria in either normal or induced animals was observed suggesting that mitochondrial matrix proteins are not released during homogenization. The hepatic mitochondrial content decreased during aging when calculated using both a membrane-bound marker enzyme cytochrome oxidase and a matrix marker enzyme citrate synthase and was unaffected by allylisopropylacetamide treatment. This reduced mitochondrial content further diminishes the level of functional ALAS available in the liver during senescence. This study confirms the age-dependent decrease in mitochondria ALAS in normal and induced animals and also suggests an age-related change in the process by which cytosolic ALAS is translocated into the mitochondria.
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PMID:Aging-related decreases in hepatic mitochondrial and cytosolic delta-aminolevulinic acid synthase during experimental porphyria. 683 17

CBL/57 strain db/db mice exhibit type II (noninsulin-dependent) diabetes. The affected mice are markedly hyperinsulinemic, hyperglycemic, and hypercholesterolemic, and their serum K+ levels are decreased. The brains of the diabetic mice are significantly smaller than those of their lean, control littermates, but the protein concentration is normal. The low brain weight is accompanied by a loss of major fatty acid components within the whole brain, nerve endings, and mitochondrial membranes. Cholesterol levels are low in whole brain but are not significantly different from normal in the synaptosomal membranes. The phospholipid concentration is significantly decreased in whole brain homogenates, crude synaptosomal membranes, and crude mitochondrial membranes of the diabetic mice. In addition, the specific activities of membrane-bound synaptosomal acetylcholinesterase, Na+,K(+)-ATPase, and Mg(2+)-ATPase are decreased in crude synaptosomal membranes of the diabetic mice. The specific activities of carnitine palmitoyltransferase I and carnitine acetyltransferase are significantly increased in the crude mitochondrial fraction isolated from the brains of the type II diabetic mice, whereas the specific activity of pyruvate dehydrogenase complex is decreased. The specific activities of two other mitochondrial enzymes--monoamine oxidase B and citrate synthase--and a cytosolic enzyme--lactate dehydrogenase--are unaltered. The ability to synthesize cyclic AMP is markedly decreased in the brains of the diabetic mice. The concentrations of carnitine and of the amino acids, glutamate, aspartate, glutamine, and serine are unaltered, whereas glycine levels are significantly elevated in the brains of the db/db mice. The data suggest that in vivo the brains of the diabetic mice exhibit a decreased capacity for glucose oxidation and increased capacity for fatty acid oxidation. This hypothesis is supported by the finding that cerebral mitochondria isolated from the db/db mice oxidize [1-14C]palmitate to 14CO2 at a rate almost twice that of control mitochondria. The present findings emphasize the potentially serious alteration of brain metabolism in uncontrolled type II diabetes.
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PMID:Lipid metabolism and membrane composition are altered in the brains of type II diabetic mice. 772 1

Geobacter sulfurreducens strain PCA oxidized acetate to CO2 via citric acid cycle reactions during growth with acetate plus fumarate in pure culture, and with acetate plus nitrate in coculture with Wolinella succinogenes. Acetate was activated by succinyl-CoA:acetate CoA-transferase and also via acetate kinase plus phosphotransacetylase. Citrate was formed by citrate synthase. Soluble isocitrate and malate dehydrogenases NADP+ and NAD+, respectively. Oxidation of 2-oxoglutarate was measured as benzyl viologen reduction and strictly CoA-dependent; a low activity was also observed with NADP+. Succinate dehydrogenase and fumarate ductase both were membrane-bound. Succinate oxidation was coupled to NADP+ reduction whereas fumarate reduction was coupled to NADPH and NADH Coupling of succinate oxidation to NADP+ or cytochrome(s) reduction required an ATP-dependent reversed electron transport. Net ATP synthesis proceeded exclusively through electron transport phosphorylation. During fumarate reduction, both NADPH and NADH delivered reducing equivalents into the electron transport chain, which contained a menaquinone. Overall, acetate oxidation with fumarate proceeded through an open loop of citric acid cycle reactions, excluding succinate dehydrogenase, with fumarate reductase as the key reaction for electron delivery, whereas acetate oxidation in the syntrophic coculture required the complete citric acid cycle.
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PMID:Oxidation of acetate through reactions of the citric acid cycle by Geobacter sulfurreducens in pure culture and in syntrophic coculture. 1113 Oct 21


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