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)

Individual muscle fibers from patients with Duchenne muscular dystrophy at an early stage in their disease, and from apparently normal boys of similar age, were analyzed for 13 enzymes of energy metabolism. This approach avoided the serious problems with muscle homogenate assays from increases in nonparenchymal components and permitted assessment of disease changes in different fiber types. Some enzymes of glycogenolysis (phosphorylase, phosphoglucomutase, and pyruvate kinase) were decreased in dystrophic fibers of all types. Phosphofructokinase was decreased in presumptive type II fibers. Lactate dehydrogenase was increased in type I fibers and essentially unchanged in type II. Phosphoglucoisomerase was near normal. Two enzymes of glucose metabolism not involved in glycogenolysis, hexokinase and glycogen synthase, were near normal, but a third, fructose bisphosphatase, was sharply reduced. Two enzymes of oxidative metabolism, citrate synthase, and beta-hydroxyacyl CoA dehydrogenase, were unchanged or increased. Two enzymes of high energy phosphate transfer, creatine kinase and adenylokinase, were only marginally affected. The net result is to leave the type II fibers, which normally exert the greatest force, with a severe deficit in the glycogenolytic enzyme machinery to maintain that force.
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PMID:Effect of Duchenne muscular dystrophy on enzymes of energy metabolism in individual muscle fibers. 360 Feb 88

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

A small animal model of arterial insufficiency has been used to investigate enzymic alterations in the gastrocnemius, plantaris and soleus muscles of the hypoperfused limb. At 7 days after induction of arterial insufficiency by unilateral femoral artery ligation, there were significant increases in the maximal activities of hexokinase, phosphorylase and 6-phosphofructokinase, whereas the activities of citrate synthase and 2-oxoglutarate dehydrogenase remained unchanged. Similar increases in hexokinase, phosphorylase and 6-phosphofructokinase were still apparent 8-10 weeks after unilateral artery ligation, although only hexokinase remained significantly higher than contralateral control values. No enhancement of oxidative enzyme activities was observed. The results are discussed in relation to the conflicting findings reported by other groups investigating enzymic adaptations in patients with arterial insufficiency.
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PMID:An investigation of arterial insufficiency in rat hindlimb. An enzymic, mitochondrial and histological study. 375 60

Maximum activities of some key enzymes of metabolism were studied in elicited (inflammatory) macrophages of the mouse and lymph-node lymphocytes of the rat. The activity of hexokinase in the macrophage is very high, as high as that in any other major tissue of the body, and higher than that of phosphorylase or 6-phosphofructokinase, suggesting that glucose is a more important fuel than glycogen and that the pentose phosphate pathway is also important in these cells. The latter suggestion is supported by the high activities of both glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. However, the rate of glucose utilization by 'resting' macrophages incubated in vitro is less than the 10% of the activity of 6-phosphofructokinase: this suggests that the rate of glycolysis is increased dramatically during phagocytosis or increased secretory activity. The macrophages possess higher activities of citrate synthase and oxoglutarate dehydrogenase than do lymphocytes, suggesting that the tricarboxylic acid cycle may be important in energy generation in these cells. The activity of 3-oxoacid CoA-transferase is higher in the macrophage, but that of 3-hydroxybutyrate dehydrogenase is very much lower than those in the lymphocytes. The activity of carnitine palmitoyltransferase is higher in macrophages, suggesting that fatty acids as well as acetoacetate could provide acetyl-CoA as substrate for the tricarboxylic acid cycle. No detectable rate of acetoacetate or 3-hydroxybutyrate utilization was observed during incubation of resting macrophages, but that of oleate was 1.0 nmol/h per mg of protein or about 2.2% of the activity of palmitoyltransferase. The activity of glutaminase is about 4-fold higher in macrophages than in lymphocytes, which suggests that the rate of glutamine utilization could be very high. The rate of utilization of glutamine by resting incubated macrophages was similar to that reported for rat lymphocytes, but was considerably lower than the activity of glutaminase.
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PMID:Metabolism of glucose, glutamine, long-chain fatty acids and ketone bodies by murine macrophages. 380 Sep 71

The present study attempts to assess whether the marked seasonal changes in the capacity for shivering thermogenesis in American goldfinches (Carduelis tristis) involve adjustments of metabolic pathways of the pectoralis muscles similar to those observed in mammalian muscle in response to endurance training, i.e., changes favoring increased reliance on fatty acid oxidation and decreased utilization of carbohydrate reserves. Analysis of seasonal changes in enzyme profile of the pectoralis muscle revealed that winter-acclimatized birds have significantly greater (P less than 0.05) activities of phosphorylase, phosphofructokinase, and beta-hydroxy-acyl-CoA dehydrogenase than do birds in other seasons. The activities of citrate synthase and hexokinase do not vary seasonally. These results differ fundamentally from the pattern of changes in enzyme activities associated with endurance adaptation in mammals. Furthermore no seasonal changes were observed in capacities for the oxidation of fatty acids (palmitate and linoleate) or pyruvate in either crude homogenates or isolated mitochondria of goldfinch pectoralis muscles. The oxidation of pyruvate by isolated pectoralis muscle mitochondria was inhibited (greater than 90%) by the oxidation of palmitoyl carnitine at palmitoyl carnitine concentrations as low as 50 microM. These data agree with physiological observations indicating little use of glucose by this tissue during steady-state shivering. However, the extent of this inhibition does not vary seasonally. Therefore the present study fails to document any significant seasonal change in the catabolic pathways of the pectoralis muscle that would link observed seasonal changes in capacity for shivering thermogenesis with a shift in the balance of substrate use by this tissue.
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PMID:Seasonal acclimatization in American goldfinches: the role of the pectoralis muscle. 622 30

The distributions of glycogen phosphorylase, hexokinase, phosphofructokinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, malate dehydrogenase, beta-hydroxyacyl CoA dehydrogenase, and adenylokinase were determined in the mudpuppy retina. Distinct differences were found in regard to the glycolytic and oxidative capacities of the various layers. In the outer retina, citric acid cycle enzymes were high while glycolytic enzymes were low. Synaptic zones were distinctly enriched in all energy-producing enzymes. Mudpuppy photoreceptors were found to be rich in phosphorylase but poor in glucose-6-phosphate dehydrogenase, suggestive of some evolutionary divergence from mammals in the metabolic machinery which is used to support the visual process.
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PMID:Enzymes of energy metabolism in the mudpuppy retina. 623 83

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

The alterations in activity patterns of representative enzymes in energy metabolism were investigated in the superficial (white) and deep (red) portions of the fast vastus lateralis muscle of the adult rat in response to prolonged endurance training. It was found that following 15 weeks of extreme training (final running duration: 210 min per day, 27 m/min at 15 degree grade), increases in the activities of marker enzymes of the citric acid cycle (citrate synthase), beta-oxidation (3-hydroxyacyl CoA dehydrogenase), and ketone body utilization (3-ketoacid CoA transferase) as well as of glutamate pyruvate transaminase occurred in both regions of the muscle, with the greatest increase being observed in the superficial portion (2.6-4.2-fold). Pronounced increases were also seen for hexokinase which showed highest activities after 7 weeks of training. Conversely, decreases were noted for various glycogenolytic, glycolytic and gluconeogenic enzymes (phosphorylase, glyceraldehydephosphate dehydrogenase, pyruvate kinase, lactate dehydrogenase and fructose-1,6-diphosphatase). Reduction in the activities of these enzymes was most pronounced in the deep portion of the muscle. These results demonstrate a fundamental rearrangement of the energy metabolism of the muscle in response to prolonged, high intensity training. In the case of the deep portion of the vastus lateralis muscle, which has been shown to be composed of a large percentage of fast oxidative-glycolytic fibres (FOG), the enzyme profile becomes similar to the slow oxidative (SO) fibre. In the superficial portion which contains predominantly fast glycolytic fibres (FG), the enzyme profile becomes similar to FOG fibres.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fibre type specific transformations in the enzyme activity pattern of rat vastus lateralis muscle by prolonged endurance training. 665 63

Muscle biopsies were obtained from three cyclists and four runners at the end of 10-24 mo of intensive training and after intervals of detraining up to 12 wk. Control samples came from four untrained persons and four former athletes. Macro mixed fiber samples were assayed for lactate dehydrogenase, adenylate kinase, glycogen phosphorylase, citrate synthase, malate dehydrogenase, beta-hydroxyacyl-CoA dehydrogenase, succinate dehydrogenase, beta-hydroxybutyrate dehydrogenase, creatine kinase, hexokinase, 1-phosphofructokinase, fructosebisphosphatase, protein, and total creatine. In the case of three trained persons and two controls, the first six of the enzymes were also measured in individual fibers. Before detraining, enzymes of oxidative metabolism were substantially higher than in controls, and differences in levels between type I and type II fibers were smaller. During detraining, oxidative enzymes were decreased in both fiber types but the type II fibers did not fall to control levels even after 12 wk. Phosphorylase increased with detraining in both fiber types. The same is true for lactate dehydrogenase and adenylate kinase, except in the case of the type I fibers of one individual. Among the other six enzymes (measured in mixed fiber samples), only hexokinase was consistently affected (decreased) by detraining.
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PMID:Effects of detraining on enzymes of energy metabolism in individual human muscle fibers. 682 50

The middle gluteal muscle of five, two-year-old untrained trotters was investigated by repeated needle biopsy sampling over a training period of six months. A second group of five, three-year-old untrained horses was included to examine the effect of growth. After the training period increases were found in the relative distribution of slow twitch (ST) fibres from 18 per cent to 25 per cent and fast twitch (FTa) fibres from 36 per cent to 45 per cent, and a decrease in FTb fibres from 46 per cent to 30 per cent. A proportionally equal reduction (approximately 18 per cent) in the cross sectional area of all fibre types was observed after the first two months of training succeeded by an increase to approximately pretraining levels at the end of the period. The number of capillaries per fibre was enhanced from 1.7 to 2.4. Proliferation of capillaries occurred around fibres of all types. The metabolic adaptations showed increases in the activities of 3-hydroxy-acyl-CoA dehydrogenase (HAD) (50 per cent) and citrate synthase (31 per cent). Growth had no effect on the relative fibre type distribution nor the capillary per fibre ratio, but as the mean fibre area increased 36 per cent (primarily because of increases in FT fibres) the number of capillaries/mm2 was lower in the older untrained horses (350 capillaries/mm2) compared with the younger untrained ones (460 capillaries/mm2). Increase with growth was found in the activity of phosphorylase and HAD and a decrease was seen in the activity of hexokinase. It is concluded that the training programme exclusively induced alterations which improved the aerobic capacity of the muscle.
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PMID:Training and growth induced changes in the middle gluteal muscle of young Standardbred trotters. 687 46


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