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)

Cell-free extracts of Rickettsia typhi were tested for activities of enzymes of the tricarboxylic acid cycle, of glutamate catabolism, and of glycolysis. The organisms were grown in the yolk sacs of chicken embryos, harvested shortly before the time of embryo death, purified by Renografin density gradient centrifugation, and ruptured in a French pressure cell. The following enzymatic activities were demonstrated: high levels of malate dehydrogenase (MDH), moderate levels of glutamate-oxaloacetate transaminase, glutamate, succinate, and isocitrate dehydrogenases, and citrate synthase, and low levels of glutamate-pyruvate transaminase. The specific activities of some of these enzymes were higher when the rickettsiae were harvested at a time of active proliferation, 3 to 4 days prior to embryo death. Rickettsial MDH was differentiated from host MDH by its migration pattern on polyacrylamide gel electrophoresis. The activities of MDH and two other dehydrogenases, demonstrable after the cells had been disrupted, were absent from purified, intact rickettsial preparations. No activity was detected for glucose-6-phosphate, 6-phosphogluconate, glyceraldehyde-3-phosphate, lactate dehydrogenases, phosphoglucose isomerase, fructoaldolase, or pyruvate kinase. Our results suggest that extracts of R. typhi that contain demonstrable enzymes involved in the catabolism of glutamate and tricarboxylic acid cycle intermediates, unlike Coxiella burnetti, lack detectable glycolytic activity.
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PMID:Enzymatic activities of cell-free extracts of Rickettsia typhi. 82 Jun 44

The enzyme pattern in gastrocnemius muscle tissue was studied in 39 patients with peripheral arterial insufficiency. Phosphofructokinase and glucose-6-phosphate-dehydrogenase were significantly increased in the skeletal muscles from these patients. The most pronounced changes were found in 3-OH-acyl-CoA-dehydrogenase, citrate synthase, and in cytochrome-c-oxidase. These enzyme activities were increased by 60, 40 and 25 per cent respectively. In patients with claudication as the only symptom, the metabolic capacity was generally increased in skeletal muscles affected by the low blood flow. With increasing severity of arterial insufficiency, all enzyme activities decreased and glycolytic enzymes were affected first. 3-OH-acyl-CoA-dehydrogenase, citrate synthase and cytochrome-c-oxidase activities were still comparatively high in patients with gangrenous foot ulcers, indicating some maintenance of the muscle viability even in situations with very low blood flow.
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PMID:Enzyme activities in skeletal muscles from patients with peripheral arterial insufficiency. 100 44

Subjective fatigue was quantified before and 20 days after uncomplicated elective abdominal surgery in 12 patients and compared with changes in heart rate, enzyme activities and skeletal muscle substrates before and after bicycle exercise for 10 min at 65 per cent of patients' preoperative maximum work capacity. Fatigue increased from a mean(s.e.m.) preoperative level of 2.5(0.5) arbitrary units to 4.6(0.5) on postoperative day 20 (P less than 0.01). Body-weight, triceps skinfold thickness and arm circumference decreased postoperatively (P less than 0.02). Postoperative values of muscle enzyme activities indicative of oxidative phosphorylation capacity (citrate synthase and 3-OH-acyl coenzyme A dehydrogenase) were lower than preoperative values (P less than 0.05). Lactate dehydrogenase was unaltered and resting values of muscle glycogen and adenosine triphosphate were higher after operation (P less than 0.05). In response to exercise, heart rate, muscle glucose, glucose-6-phosphate and lactate increased (P less than 0.05), while muscle glycogen and creatine phosphate decreased (P less than 0.05). Increase in postoperative fatigue correlated with the increase in heart rate (P less than 0.05), while no significant correlations were found between fatigue and muscle parameters. Our results suggest that lack of exercise and malnutrition may be of importance in the decrease in work capacity and in fatigue after operation.
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PMID:Skeletal muscle enzyme activities and metabolic substrates during exercise in patients with postoperative fatigue. 232 98

Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose-6-phosphate, pyruvate, lactate), Krebs cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate), related free amino acids (glutamate, alanine), ammonia, energy store (creatine phosphate), energy mediators (ATP, ADP, AMP) and energy charge potential were evaluated. Furthermore the maximum rate (Vmax) of the following muscular enzyme activities was evaluated in the crude extract and/or mitochondrial fraction: for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; for the tricarboxylic acid cycle: citrate synthase, malate dehydrogenase; for the electron transfer chain: total NADH cytochrome c reductase, cytochrome oxidase. The rat gastrocnemius muscles were analyzed in normoxia and after repeated, alternate hypoxic and normoxic exposures (12 hours of hypoxia daily; for 5 days). Naftidrofuryl was administered daily at three different doses: 10, 15 and 22.5 mg/kg i.m., 30 min before the beginning of the experimental hypoxia. The biochemical adaptation to intermittent normobaric hypoxic-normoxic exposures was characterized by the decrease of the muscular contents of creatine phosphate, citrate, alpha-ketoglutarate and glutamate. This adaptation occurred in absence of significant changes in the Vmax of the muscle enzymes tested. By naftidrofuryl treatment, in gastrocnemius muscle from hypoxic rats both alpha-ketoglutarate and creatine phosphate contents maintained normal values, while glutamate concentration remained reduced to subnormal values. With the exception of hexokinase, naftidrofuryl treatment did not modify the Vmax of marker enzymes related to energy transduction.
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PMID:Adaptation of skeletal muscle energy metabolism to repeated hypoxic-normoxic exposures and drug treatment. 401 59

Muscular glycolytic fuels, intermediates and end-products (glycogen, glucose, glucose-6-phosphate, pyruvate, lactate), Krebs cycle intermediates (citrate, alpha-ketoglutarate, succinate, malate), related free amino acids (glutamate, alanine), ammonia, energy store (creatine phosphate), energy mediators (ATP, ADP, AMP) and energy charge potential were evaluated. Furthermore the maximum rate (Vmax) of the following enzyme activities was evaluated in the crude extract and/or mitochondrial fraction: for the anaerobic glycolytic pathway: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase; for the tricarboxylic acid cycle: citrate synthase, malate dehydrogenase; for the electron transfer chain: total NADH cytochrome c reductase, cytochrome oxidase. The rat gastrocnemius muscles were analysed in normoxia and after normobaric intermittent hypoxia (12 hours continuously daily; for 5 days). Cytidine and/or uridine were administered daily at the dose of 120 mg/kg, i.p., 30 min before the beginning of the experimental hypoxia. The intermittent normobaric hypoxia induced a biochemical adaptation characterized by the decrease of the muscular contents of creatine phosphate, citrate, alpha-ketoglutarate and glutamate. This adaptation occurred in the absence of significant changes in the Vmax of the tested muscle enzymes. In gastrocnemius muscle from hypoxic rats, the two biological pyrimidines tested induced various discrete, but often related, modifications of the contents of some Krebs cycle intermediates (i.e., alpha-ketoglutarate, malate) and related free amino acids (i.e., glutamate, alanine). In any case, the treatment with cytidine and/or uridine did not modify the Vmax of marker enzymes related to energy transduction.
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PMID:Modification of the skeletal muscle energy metabolism induced by intermittent normobaric hypoxia and treatment with biological pyrimidines. 402 89

Spheroplast membranes (spheroplast envelopes) of strain 2091 of group B Neisseria meningitidis were prepared by a procedure that included lysozyme treatment of the cells and osmotic lysis of the resulting spheroplasts. Electron microscopy revealed that the membranes consisted of two unit layers, generally parallel to each other. The membrane preparation migrated as a single component in a 40 to 70% sucrose gradient and consisted of 62% protein, 28% lipid, 9% ribonucleic acid, small amounts of carbohydrate, hexosamine, and deoxyribonucleic acid. When 1 or 10 mug (dry weight) was injected intravenously into rabbits, a mild pyrogenic reaction was elicited. In immunodiffusion tests, immune rabbit serum prepared against spheroplast membranes produced three major precipitin lines, with the homologous antigen solubilized with sodium dodecyl sulfate, and a single line with untreated antigen. The immune serum also reacted with a cell wall antigen, and to a lesser extent with some of the cytoplasmic antigens. Succinate dehydrogenase and reduced nicotinamide adenine dinucleotide (NADH) oxidase activities were found to be associated with the spheroplast membranes. NADH dehydrogenase also was associated with the membranes but was gradually released and recovered in other fractions. Glutamate-oxaloacetate transaminase, glutamate, glucose-6-phosphate, and isocitrate dehydrogenase activities were not found in the membrane preparation. About one-third of these enzymatic activities were recovered in the supernatant fluid after the sedimentation of the spheroplasts and two-thirds were recovered in the cytoplasmic fraction. N-acetylneuraminic acid (NAN)-condensing enzyme and cytidine monophosphate-NAN synthesizing enzyme also were identified in this organism. These enzymes were not associated with the membranes and were recovered from extracts from whole cells, spheroplasts, or cells exposed to osmotic shock, as well as from spheroplast supernatant and shock fluids. It is concluded that the spheroplast membranes of the strain of meningococci used in these studies are typical of those recovered from gram-negative bacteria.
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PMID:Characterization of spheroplast membranes of Neisseria meningitidis group B. 463 Jul 22

Burton, Sheril D. (Institute of Marine Science, University of Alaska, College), Richard Y. Morita, and Wayne Miller. Utilization of acetate by Beggiatoa. J. Bacteriol. 91:1192-1200. 1966.-A proposed system which would permit acetate incorporation into four-carbon compounds without the presence of key enzymes of the citric acid cycle or glyoxylate cycle is described. In this system, acetyl-coenzyme A (CoA) is condensed with glyoxylate to form malate, which, in turn, is converted to oxaloacetate. Oxaloacetate then reacts with glutamate to produce alpha-ketoglutarate, which is subsequently converted to isocitrate. Cleavage of isocitrate produces glyoxylate and succinate. Thus, the proposed system is similar to the glyoxylate bypass in that malate is produced from glyoxylate and acetyl-CoA, but differs from both the citric acid cycle and the glyoxylate bypass, since citrate and fumarate are not involved. Fumarase, aconitase, catalase, citritase, pyruvate kinase, enolase, phosphoenolpyruvate carboxylase, lactic dehydrogenase, alpha-ketoglutarate dehydrogenase, and condensing enzyme were not detectable in crude extracts of Beggiatoa. Succinate was oxidized by a soluble enzyme not associated with an electron-transport particle. Isocitrate was identified as the sole compound labeled when C(14)O(2) was added to a reduced nicotinamide adenine dinucleotide, CO(2) generating system (crystalline glucose-6-phosphate dehydrogenase and glucose-6-phosphate) in the presence of alpha-ketoglutarate.
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PMID:Utilization of acetate by Beggiatoa. 592 51

Strain SF22, a glutamine-requiring (Gln-) mutant of Bacillus subtilis SMY, is likely to have a mutation in the structural gene for glutamine synthetase, since this strain synthesized 22 to 55% as much glutamine synthetase antigen as did wild-type cells in a 10-min period but had less than 3% of wild-type glutamine synthetase enzymatic activity. The expression of several genes subject to glucose catabolite repression was altered in the Gln- mutant. The induced levels of alpha-glucosidase, histidase, and aconitase were 3.5- to 4-fold higher in SF22 cells than in wild-type cells grown in glucose-glutamine medium, and citrate synthase levels were 8-fold higher in the Gln- mutant than in wild-type cells. The relief of glucose catabolite repression in the Gln- mutant may result from poor utilization of glucose. Examination of the intracellular metabolite pools of cells grown in glucose-glutamine medium showed that the glucose-6-phosphate pool was 2.5-fold lower, the pyruvate pool was 4-fold lower, and the 2-ketoglutarate pool was 2.5-fold lower in the Gln- cells than they were in wild-type cells. Intracellular levels of glutamine were sixfold higher in the Gln- mutant than in wild-type cells. Measurements of enzymes involved in glutamine transport and utilization showed that the elevated pools of glutamine in the Gln- mutant resulted from a threefold increase in glutamine permease and a fivefold decrease in glutamate synthase. The pleiotropic effect of the gln-22 mutation on the expression of several genes suggests that either the glutamine synthetase protein or its enzymatic product, glutamine, is involved in the regulation of several metabolic pathways in B. subtilis.
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PMID:Bacillus subtilis glutamine synthetase mutants pleiotropically altered in glucose catabolite repression. 614 Nov 56

Biopsies from 15 human gliomas, five meningiomas, four Schwannomas, one medulloblastoma, and four normal brain areas were analyzed for 12 enzymes of energy metabolism and 12 related metabolites and cofactors. Samples, 0.01-0.25 microgram dry weight, were dissected from freeze-dried microtome sections to permit all the assays on a given specimen to be made, as far as possible, on nonnecrotic pure tumor tissue from the same region. Great diversity was found with regard to both enzyme activities and metabolite levels among individual tumors, but the following generalities can be made. Activities of hexokinase, phosphorylase, phosphofructokinase, glycerophosphate dehydrogenase, citrate synthase, and malate dehydrogenase levels were usually lower than in brain; glycogen synthase and glucose-6-phosphate dehydrogenase were usually higher; and the averages for pyruvate kinase, lactate dehydrogenase, 6-phosphogluconate dehydrogenase, and beta-hydroxyacyl coenzyme A dehydrogenase were not greatly different from brain. Levels of eight of the 12 enzymes were distinctly lower among the Schwannomas than in the other two groups. Average levels of glucose-6-phosphate, lactate, pyruvate, and uridine diphosphoglucose were more than twice those of brain; 6-phosphogluconate and citrate were about 70% higher than in brain; glucose, glycogen, glycerol-1-phosphate, and malate averages ranged from 104% to 127% of brain; and fructose-1,6-bisphosphate and glucose-1,6-bisphosphate levels were on the average 50% and 70% those of brain, respectively.
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PMID:Diversity of metabolic patterns in human brain tumors: enzymes of energy metabolism and related metabolites and cofactors. 661 61

Impaired muscle glucose phosphorylation to glucose-6-phosphate by hexokinases (HKs)-I and -II may contribute to insulin resistance in NIDDM and obesity. HK-II expression is regulated by insulin. We tested the hypothesis that basal and insulin-stimulated expression of HK-II is decreased in NIDDM and obese subjects. Skeletal muscle HK-I and HK-II activities were measured in seven lean and six obese normal subjects and eight patients with NIDDM before and at 3 and 5 h of a hyperinsulinemic (80 mU x m(-2) x min(-1)) euglycemic clamp. To assess whether changes in HK-II expression seen during a glucose clamp are likely to be physiologically relevant, we also measured HK-I and HK-II activity in 10 lean normal subjects before and after a high-carbohydrate meal. After an overnight fast, total HK, HK-I, and HK-II activities were similar in lean and obese control subjects; but HK-II was lower in NIDDM patients than in lean subjects (1.42 +/- 0.16 [SE] vs. 2.33 +/- 0.24 nmol x min(-1) x mg(-1) molecular weight, P < 0.05) and accounted for a lower proportion of total HK (33 +/- 3 vs. 47 +/- 3%, P < 0.025). HK-II (but not HK-I) activity increased during the clamp in lean and obese subjects by 34 and 36% after 3 h and by 14 and 22% after 5 h of hyperinsulinemia; no increase was found in the NIDDM patients. In the lean subjects, muscle HK-II activity also increased by 15% 4 h after the meal, from 2.47 +/- 0.19 basally to 2.86 +/- 0.28 nmol x min(-1) x mg(-1) protein (P < 0.05). During the clamps, muscle HK-II activity correlated with muscle citrate synthase activity in the normal subjects (r = 0.58, P < 0.05) but not in the NIDDM patients. A weak relationship was noted between muscle HK-II activity and glucose disposal rate at the end of the clamp when all three groups were combined (r = 0.49, P < 0.05). In summary, NIDDM patients have lower muscle HK-II activity basally and do not increase the activity of this enzyme in response to a 5-h insulin stimulus. This defect may contribute to their insulin resistance. In nondiabetic obese subjects, muscle HK-II expression and its regulation by insulin are normal.
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PMID:Regulation of skeletal muscle hexokinase II by insulin in nondiabetic and NIDDM subjects. 964 35


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