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)

Microbodies appearing abundantly in n-alkane-grown cells of Candida tropicalis pK 233 were isolated by means of sucrose density gradient centrifugation. Electron microscopical observation showed that the microbodies isolated were intact. Localization of catalase and D-amino acid oxidase in the isolated microbodies was confirmed. Isocitrate lyase, melate synthase and NADP-linked isocitrate dehydrogenase were also located in the microbody, but malate dehydrogenase, citrate synthase, aconitase and NAD-linked isocitrate dehydrogenase were not. Neither cytochrome P-450 not NADPH-cytochrome c reductase, the components involved in the n-alkane hydroxylation system of the yeast, were detected in the microbody fraction.
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PMID:Microbody of n-alkane-grown yeast. Enzyme localization in the isolated microbody. 84 63

To characterize the lipid and the energy metabolism in the livers of genetically different types of pigs (land race pig and mini pig), the authors determined the activities of enzymes typical of and limiting these metabolic pathways. Furthermore, they measured the concentrations of typical metabolites and ascertained parameters that are of importance in energy metabolism. The concentrations of acetyl CoA and free fatty acids in the livers of mini pigs were significantly greater than those in the livers of land race pigs, whereas the cholesterol, glycerol, triglyceride and acetoacetate concentrations were reduced. The activities of glucose-6-phosphate dehydrogenase (E.C.1.1.1.49.), citrate synthase (E.C.4.1.3.7.) and ATP citrate lyase (E.C.4.1.3.8.) were lower in the livers of mini pigs than in the livers of land race pigs, whereas the activity of fatty acid synthase was higher. The concentrations of cyclic 3',5'-adenosine monophosphate (AMP) and adenosine diphosphate (ADP) were lower in the livers of mini pigs than in those of land race pigs. In land race pigs, the metabolic process seems, therefore, to be determined in favour of the degradation of free fatty acids and of the generation of energy. In mini pigs, lipogenesis in the liver appears to be the decisive metabolic pathway. The possibility of a higher coordinating control mechanism of the lipid and the energy metabolism is discussed.
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PMID:[Behavior of certain parameters of lipid and energy metabolism. IV. Regulation of lipid and energy metabolism in livers and race and mini pigs]. 84 65

1. The development of pyruvate dehydrogenase and citrate synthase activity in rat brain mitochondria was studied. Whereas the citrate synthase activity starts to increase at about 8 days after birth, that of pyruvate dehydrogenase starts to increase at about 15 days. Measurements of the active proportion of pyruvate dehydrogenase during development were also made. 2. The ability of rat brain mitochondria to oxidize pyruvate follows a similar developmental pattern to that of the pyruvate dehydrogenase. However, the ability to oxidize 3-hydroxybutyrate shows a different developmental pattern (maximal at 20 days and declining by half in the adult), which is compatible with the developmental pattern of the ketone-body-utilizing enzymes. 3. The developmental pattern of both the soluble and the mitochondrially bound hexokinase of rat brain was studied. The total brain hexokinase activity increases markedly at about 15 days, which is mainly due to an increase in activity of the mitochondrially bound form, and reaches the adult situation (approx. 70% being mitochondrial) at about 30 days after birth. 4. The release of the mitochondrially bound hexokinase under different conditions by glucose 6-phosphate was studied. There was insignificant release of the bound hexokinase in media containing high KCl concentrations by glucose 6-phosphate, but in sucrose media half-maximal release of hexokinase was achieved by 70mum-glucose 6-phosphate 5. The production of glucose 6-phosphate by brain mitochondria in the presence of Mg(2+)+glucose was demonstrated, together with the inhibition of this by atractyloside. 6. The results are discussed with respect to the possible biological significance of the similar developmental patterns of pyruvate dehydrogenase and the mitochondrially bound kinases, particularly hexokinase, in the brain. It is suggested that this association may be a mechanism for maintaining an efficient and active aerobic glycolysis which is necessary for full neural expression.
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PMID:Development of mitochondrial energy metabolism in rat brain. 88 Feb 41

1. Bicarbonate increased citrate and 2-oxoglutarate accumulation when rat kidney cortex mitochondria were incubated with pyruvate or L(-)-palmitoyl carnitine in the presence of L-malate. 2. Bicarbonate stimulated the exit of citrate from mitochondria. The Km for bicarbonate was 13.5 mM and the Vmax was 0.59 nmol/min/mg of protein at 10 degrees. 3. The bicarbonate-stimulated exit of citrate from the mitochondria was prevented by inhibitors of the tricarboxylate, dicarboxylate, and phosphate transport systems. 4. The activity of pyruvate dehydrogenase was significantly increased by preincubation of rat kidney mitochondria with bicarbonate. This bicarbonate-induced activation was not observed in presence of inhibitors of citrate transport. Bicarbonate did not activate pyruvate dehydrogenase in rat heart mitochondria. Bicarbonate had no effect on pyruvate dehydrogenase activity in either broken mitochondria or whole tissue preparations. 5. The mechanism of this activation is discussed in the light of the known regulatory properties of pyruvate dehydrogenase, pyruvate carboxylase, and citrate synthase.
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PMID:Regulation of citrate transport and pyruvate dehydrogenase in rat kidney cortex mitochondria by bicarbonate. 88 71

The mechanism of the massive extracellular production of citric and isocitric acids by Saccharomycopsis lipolytica grown on n-paraffins has been studied. When growth stops, because of nitrogen limitation, the intracellular concentration of ATP sharply rises whereas that of AMP and ADP decreases to a low level. At the same time production of acids begins. The activity of the NAD-dependent isocitrate dehydrogenase which requires AMP for activity becomes very low and prevents the oxidative function of the citric acid cycle whereas isocitrate lyase is not inhibited. As citrate synthase inhibition by ATP appears to be insufficient to stop n-paraffin degradation, citric and isocitric acids accumulation can take place. Massive excretion of these acids, however, probably still involves other physiological changes brought about by nitrogen limitation, possibly some permeabilization of the cell to these acids.
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PMID:Regulation of the central metabolism in relation to citric acid production in Saccharomycopsis lipolytica. 88 90

Citrate synthase activity in soluble human muscle extracts (KCl-containing triethanolamine buffer) amounts to 17.5+/-6.97 U/g wet weight at 37 degrees C (n=36 healthy male subjects). Double determinations, both using two procedures and with muscle samples divided into two pieces and analyzed separately, gave very good reproducibilities. The possible causes of the comparatively high values are discussed. Significant correlations of citrate synthase activity with NADP-linked isocitrate dehydrogenase (r=+0.826) and hexose phosphate isomerase (r=-0.582) were found. The distribution of citrate synthase activity in the samples studied is not of the normal type but appears to be binomial.
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PMID:Citrate synthase activity in human skeletal muscle. 89 12

In biopsy samples of the lateral part of the quadriceps femoris muscle of 6 obese diabetic male patients and of 11 obese males with a normal glucose tolerance, the activities of 7 enzymes of energy metabolism were estimated: hexokinase, cytoplasmic glycerol-3-phosphate: NAD dehydrogenase, triosephosphate dehydrogenase, lactate dehydrogenase, citrate synthase, malate dehydrogenase and 3-hydroxyacyl-CoA dehydrogenase. The obese diabetic male patients exhibited decreased activities of enzymes of carbohydrate breakdown and cytoplasmic NAD regeneration. Enzymes connected functionally with aerobic metabolism were less affected. The unchanged activity of 3-hydroxyacyl-CoA dehydrogenase points to an increased role of fatty acid catabolism in the muscle.
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PMID:Enzyme activities in quadriceps femoris muscle of obese diabetic male patients. 90 76

alpha-Ketoglutarate: glyoxylate carboligase activity has been reported by other laboratories to be present in mitochondria and in the cytosol of mammalian tissues; the mitochondrial activity is associated with the alpha-ketoglutarate decarboxylase moiety of the alpha-ketoglutarate dehydrogenase complex. The cellular distribution of the carboligase has been re-examined here using marker enzymes of known localization in order to monitor the composition of subcellular fractions prepared by differential centrifugation. Carboligase activity paralleled the activity of the mitochondrial matrix enzyme citrate synthase in subcellular fractions prepared from rat liver, heart and brain as well as from rabbit liver. Whole rat liver mitochondria upon lysis released both carboligase and citrate synthase. The activity patterns of several other extramitochondrial marker enzymes differed significantly from that of carboligase in rat liver. In addition, the distribution pattern of carboligase was similar to that of alpha-ketoglutarate decarboxylase and of alpha-ketoglutarate dehydrogenase complex. The data indicate that alpha-ketoglutarate: glyoxylate carboligase activity is located exclusively within the mitochondria of the rat and rabbit tissues investigated. There is no evidence for a cytosolic form of the enzyme. Thus the report from other laboratory that the molecular etiology of the human genetic disorder hyperoxaluria type I is a deficiency of cytosolic carboligase must be questioned.
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PMID:Cellular localization of alpha-ketoglutarate: glyoxylate carboligase in rat tissues. 91 88

The effects of aging on the oxidation of labeled glucose and 3-hydroxybutyrate and on several mitochondrial enzymes in rat brain were investigated. The oxidation of labeled glucose and labeled 3-hydroxybutyrate was diminished by about 40 and 35%, respectively, in cerebral cortex slices from 2-year-old rats compared to those from 3-mo-old animals. A significant reduction in the activities of 3-hydroxybutyrate dehydrogenase, 3-oxo acid CoA transferase, acetoacetyl CoA thiolase, and NAD-isocitrate dehydrogenase was observed in brains of 1- and 2-year-old rats compared to 3-mo-old animals. However, aging had no effect on the activities of citrate synthase and pyruvate carboxylase. These findings show that specific alterations occur in the activities of several mitochondrial enzymes in aging brain.
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PMID:Age-dependent changes in the oxidative metabolism in rat brain. 91 4

Enterobacter aerogenes was grown in continous culture with ammonia as the growth-limiting substrate, and changes in citrate lyase and citrate synthase activities were monitored after growth shifts from anaerobic growth on citrate to aerobic growth on citrate, aerobic growth on glucose, anaerobic growth on glucose, and anaerobic growth on glucose plus nitrate. Citrate lyase was inactivated during aerobic growth on glucose and during anaerobic growth with glucose plus nitrate. Inactivation did not occur during anaerobic growth on glucose, and as a result of the simultaneous presence of citrate lyase and citrate synthase, growth difficulties were observed. Citrate lyase inactivation consisted of deacetylation of the enzyme. The corresponding deacetylase could not be demonstrated in cell extracts, and it is concluded that, as in a number of other inactivations, electron transport to oxygen or nitrate was required for inactivation.
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PMID:Energy-dependent inactivation of citrate lyase in Enterobacter aerogenes. 92 71


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