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)

To determine whether respiratory muscles undergo alterations in enzyme activities of energy metabolism as a result of increased mechanical activity, adult male Wistar rats were subjected to a prolonged endurance training program. Analysis off maximal enzyme activity patterns in the diaphragm following 15 weeks of extreme training (final running duration: 210 min per day, 27 m.min-1 at 15 degrees grade, indicated significant reductions in the marker enzymes of the citric acid cycle (citrate synthase), glycolysis (pyruvate kinase, PK; lactate dehydrogenase, LDH), ketone body utilization (3-keto acid: CoA transferase) and transamination (glutamate pyruvate transaminase, GPT). No changes were found for the enzymes of glycogenolysis (phosphorylase, PHOSPH), glycolysis (glyceraldehyde phosphate dehydrogenase, GAPDH), glucose phosphorylation (hexokinase, HK) and beta-oxidation (3-hydroxyacyl: CoA dehydrogenase, HAD) following training. In contrast, in the external intercostal muscle, increases in the range of 57-77% were noted for the enzymes CS and HAD, whereas in the internal intercostal muscles no training induced alteration was evident for these enzymes. For both the intercostal muscles, a consistent trend was noted towards a reduction in all of the glycolytic enzymes investigated, however, significantly lower values were recorded for only PK and LDH in the internal intercostals. GPT was increased in the internal intercostal muscles. These findings indicate that the response pattern observed in the enzyme activities studied following training are to some degree specific to the respiratory muscle investigated.
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PMID:Differential response of enzyme activities in rat diaphragm and intercostal muscles to exercise training. 337 43

The genes encoding both subunits of the succinyl-CoA synthetase of Escherichia coli have been identified as distal genes of the suc operon, which also encodes the dehydrogenase (Elo; sucA) and succinyltransferase (E2o; sucB) components of the 2-oxoglutarate dehydrogenase complex. The newly defined genes express polypeptides of 41 kDa (sucC) and 31 kDa (sucD), corresponding to the beta and alpha subunits of succinyl-CoA synthetase, respectively. The genes are thus located at 16.8 min in the E. coli linkage map, together with the citrate synthase (gltA) and succinate dehydrogenase (sdh) genes, in a cluster of nine citric acid cycle genes: gltA-sdhCDAB-sucABCD. Four deletion strains lacking all of these citric acid cycle enzymes were characterized. The succinyl-CoA synthetase activities of strains harbouring plasmids containing the sucC and sucD genes were amplified some fourfold. Further enzymological studies indicated that expression of succinyl-CoA synthetase is coordinately regulated with 2-oxoglutarate dehydrogenase.
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PMID:Cloning and expression of the succinyl-CoA synthetase genes of Escherichia coli K12. 354 12

We determined representative enzyme activities of glycogenolysis (glycogen phosphorylase) glycolysis (d-glyceraldehyde-3-phosphate dehydrogenase, GAPDH), beta oxidation of free fatty acids (1-3-hydroxyacyl CoA dehydrogenase, HADH), citric acid cycle (citrate synthase, CS), lactate fermentation (lactate dehydrogenase LDH), and creatine phosphate metabolism (creatine kinase, CK) in left ventricular samples of 36 patients to investigate if the metabolic capacities of the energy-supplying pathways are differently affected in different heart diseases. There were 17 patients with mitral valve diseases (MVD), 8 patients with aortic valve diseases (AVD), and 11 patients who suffered from dilative cardiomyopathies (DCM). The main metabolic characteristic on the level of enzymatic organization in patients with DCM was an increased ratio of GAPDH/HADH activities and a decreased ratio of HADH/CS activities compared to the valve-diseased patients. This result indicates that the capacity of glucose oxidation is enhanced at the expense of fatty acid metabolism in patients with DCM. Furthermore, we determined significantly lower myocardial CK activities in this group of patients, most probably reflecting a diminished content of myofibrils. Citrate synthase activity was lowest in patients with AVD. Although we cannot rule out that the impaired left ventricular function is in part responsible for the shift of the capacities of the energy-supplying metabolism in patients with DCM, we favor the assumption that it is a specific feature of this myocardial disease.
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PMID:Comparative analysis of myocardial enzyme activities of the energy-supplying metabolism in patients with dilative cardiomyopathies and valve diseases. 370 46

Simulation of reparative osteogenesis in diaphysis fracture of rat femur showed that liver tissue citrate synthase was a key enzyme in metabolism of citrate under conditions of organic matrix development in regenerating tissue. The liver enzyme as well as the callus citrate synthase were responsible for high rate of lipogenesis (activation of ATP-citrate lyase) and for an increase in content of citric acid within the initial period of consolidation. At the late steps of reparation callus citrate synthase, involved in citrate metabolism, promoted activation of energy-dependent reactions of calcification (stimulation of NAD-isocitrate dehydrogenase) and determined the dynamics of the metabolite concentration.
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PMID:[Citrate metabolism during the consolidation of experimental fractures]. 377 17

The activities of certain key enzymes have been measured in the ventral medial and ventral lateral areas of the hypothalamus, which are implicated in feeding behaviour, and compared with enzyme activities in the cortex and brainstem. The enzymes measured are concerned with glucose metabolism [hexokinase (EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49)], ketone body metabolism [3-hydroxybutyrate dehydrogenase (EC 1.1.1.30)], fatty acid utilisation [carnitine palmitoyl transferase (EC 2.3.1.7)], citric acid cycle activity [pyruvate dehydrogenase (EC 1.2.4.2) and citrate synthase (EC 4.1.3.7)] and neurotransmitter synthesis [glutamate dehydrogenase (EC 1.4.1.3)].
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PMID:Enzyme activities in regions of the hypothalamus. 380 3

Some enzyme activities and metabolic features of the black Ma melanotic, brown MI melanotic and Ab amelanotic melanomas of hamster were investigated. The activities of hexokinase and phosphofructokinase were similar in all three melanomas, the activity of NAD-dependent glycerol-3-phosphate dehydrogenase was higher in the amelanotic melanoma and that of pyruvate kinase and lactate dehydrogenase were slightly lower in MI than in the other tumors. The activities of citrate synthase, succinate dehydrogenase and malate dehydrogenase were higher in the Ma and MI melanotic melanomas than in the Ab amelanotic melanoma. The rate of labeled CO2 production from 6-14C-glucose, 1,5-14C-citric acid and U-14C-glutamine was about 2 times higher in melanotic melanomas than in amelanotic one, while no significant differences among the three melanomas were found in respect to 1-14C-glucose and U-14C-glycerol-3-phosphate. The production of 14CO2 was much higher from 1-14C-glucose than from 6-14C-glucose in all the melanomas studied. L-DOPA stimulated the production of 14CO2 from 1-14C-glucose much stronger in the Ma and MI melanomas than in the Ab melanoma. In none of the tumors the incorporation from 6-14C-glucose to CO2 was affected by L-DOPA. It is postulated that oxidation of glucose via the pentose phosphate cycle is involved in melanogenesis.
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PMID:Metabolic characterization of three hamster melanoma variants. 406 92

Common carp (Cyprinus carpio L.), 1 kg body weight, were acclimated for 1-2 months to water temperatures of either 7-8 degrees C (cold-acclimated group) or 23-24 degrees C (warm-acclimated group). Single fast fibres and small bundles of slow fibres were isolated from the myotomal muscles and chemically skinned. Force-velocity (P-V) characteristics were determined at 7 degrees C and 23 degrees C. The contractile properties of carp muscle fibres are dependent on acclimation temperature. In the warm-acclimated group maximum isometric tensions (P0, kN m-2) are 47 +/- 6 and 64 +/- 5 for slow muscle fibres and 76 +/- 10 and 209 +/- 21 for fast muscle fibres at 7 degrees C and 23 degrees C, respectively. Maximum contraction velocities (Vmax, muscle lengths-1), are 0.4 +/- 0.05 and 1.5 +/- 0.1 at 7 degrees C (slow fibres) and 0.6 +/- 0.04 and 1.9 +/- 0.4 at 23 degrees C (fast fibres). All values represent mean +/- S.E. P0 and Vmax at 7 degrees C are around 1.5-2.0 times higher for slow and fast muscle fibres isolated from the cold-acclimated group. Fibres from 7 degrees C-acclimated carp fail to relax completely following maximal activations at 23 degrees C. The resulting Ca-insensitive force component (50-70% P0) is associated with the development of abnormal crossbridge linkages and very slow contraction velocities. Activities of enzymes associated with energy metabolism were determined at a common temperature of 15 degrees C. Marker enzymes of the electron transport system (cytochrome oxidase), citric acid cycle (citrate synthase), fatty acid metabolism (carnitine palmitoyl transferase, beta-hydroxyacyl CoA dehydrogenase) and aerobic glucose utilization (hexokinase) have 30-60% higher activities in slow muscle from cold-acclimated than from warm-acclimated fish. Activities of cytochrome oxidase and citrate synthase in fast muscle are also elevated following acclimation to low temperature. It is concluded that thermal compensation of mechanical power output by carp skeletal muscle is matched by a concomitant increase in the potential to supply aerobically-generated ATP at low temperatures.
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PMID:Force-velocity characteristics and metabolism of carp muscle fibres following temperature acclimation. 409 57

The synthesis of aconitase in Bacillus subtilis wild-type and different citric acid cycle mutants has been studied and the influence of various growth conditions examined. Aconitase is induced by citrate and precursors of citrate and repressed by glutamate. Induction and repression counteract each other, and at equimolar concentrations of citrate and glutamate, aconitase synthesis is unaffected. Induction by citrate can partly overcome catabolite repression of aconitase. Isocitrate dehydrogenase show endogenous induction of aconitase due to citrate accumulation. Leaky mutants defective in citrate synthase and aconitase cannot be induced by citrate, which indicates that they carry a regulatory mutation. The complex regulation of aconitase is discussed with reference to the participation of this enzyme in glutamate biosynthesis and energy metabolism.
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PMID:Regulation of aconitase synthesis in Bacillus subtilis: induction, feedback repression, and catabolite repression. 420 96

The synthesis of citric and glutamic acids by extracts of Chloropseudomonas ethylicum was studied with labeled precursors. When acetyl-coenzyme A-1-(14)C was used as substrate, only 0.1% of the total radioactivity was found in the C-5 position of citric acid; whereas, with oxalacetate-4-(14)C as substrate, 100% of the total radioactivity was found in C-5. These results demonstrated that the Chloropseudomonas citrate synthetase had an absolute stereospecificity, identical to that of the pig heart synthetase. The distribution of radioactivity in the glutamic acid synthesized from acetyl-coenzyme A-1-(14)C was 0% in C-1 and 94.0% in C-5; whereas the glutamic acid formed from oxalacetate-4-(14)C contained 89.6% in C-1 and 0.5% in C-5. This distribution is entirely consistent with the biosynthesis of glutamic acid from citric acid via aconitase, d(s)-isocitrate, and l-glutamate dehydrogenases. The presence of l-glutamate dehydrogenase in extracts was demonstrated. The stereospecificity of the citrate synthetase and the pattern of glutamate labeling further establish that the aconitase of Chloropseudomonas is completely stereospecific.
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PMID:Stereospecificity of citrate synthetase in relation to glutamate biosynthesis by extracts of Chloropseudomonas ethylicum. 564 42

The activities of the eight citric acid-cycle enzymes of rat bone-marrow cells were determined along with several other mitochondrial and non-mitochondrial enzymes. Four of the citric acid-cycle enzymes (aconitase, succinyl-CoA thiokinase, alpha-oxoglutarate dehydrogenase and succinate dehydrogenase) have closely similar low activities; two [isocitrate dehydrogenase (NAD) and citrate synthase] have intermediate activities; the remaining two (malate dehydrogenase and fumarase) have high activities. The other enzymes surveyed also exhibited a spread of three orders of magnitude, the mitochondrial enzymes showing no less variation than the others.
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PMID:The activities of the citric acid-cycle enzymes in rat bone-marrow cells. 566 55


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