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

Modifications of enzyme activities (creatine kinase and its B subunit; adenylate kinase; hexokinase; phosphofructokinase; lactate dehydrogenase; malate dehydrogenase, isocitrate dehydrogenase; citrate synthase; acetylcarnitine transferase; beta-hydroxyacetyl-CoA dehydrogenase; cytochrome c oxidase) in gastrocnemius muscle and myocardium were reported after two forms of training with or without administration of anabolic steroid. Endurance training was on a horizontal motor-driven treadmill, 2 km X hr-1, 5 days a week for 0.5 hr per day for 5 weeks. In the case of power endurance training there was a slope of 45 degrees. Enzyme activities in controls and treated guinea pigs, as well as treatment-induced enzyme activity changes are time dependent. Some of these activities correlate linearly with one another; such correlations characterize the effect of adaptation. Endurance training and power endurance training in this study induce similar modifications and seem to differ essentially in the daily work load. The anabolic steroid methandrostenolone (dianabol) induces modifications which training does not bring about but which training at least partially eliminates.
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PMID:Effects of training and methandrostenolone (an anabolic steroid) on energy metabolism in the guinea pig: changes in enzyme activities in gastrocnemius muscle and myocardium. 407 21

Mitochondria from the muscle of the parasitic nematode Ascaris lumbricoides var. suum function anaerobically in electron transport-associated phosphorylations under physiological conditions. These helminth organelles have been fractionated into inner and outer membrane, matrix, and intermembrane space fractions. The distributions of enzyme systems were determined and compared with corresponding distributions reported in mammalian mitochondria. Succinate and pyruvate dehydrogenases as well as NADH oxidase, Mg(++)-dependent ATPase, adenylate kinase, citrate synthase, and cytochrome c reductases were determined to be distributed as in mammalian mitochondria. In contrast with the mammalian systems, fumarase and NAD-linked "malic" enzyme were isolated primarily from the intermembrane space fraction of the worm mitochondria. These enzymes are required for the anaerobic energy-generating system in Ascaris and would be expected to give rise to NADH in the intermembrane space. The need for and possible mechanism of a proton translocation system to obtain energy generation is suggested.
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PMID:Enzyme localization in the anaerobic mitochondria of Ascaris lumbricoides. 415 73

1. With freshly isolated blowfly mitochondria 38% of the intramitochondrial adenine nucleotide was present as AMP. 2. On incubation with oxidizable substrates the AMP and ADP concentrations fell and that of ATP rose; with pyruvate together with proline the ATP concentration reached its maximum value at 6min; with glycerol phosphate the phosphorylation of endogenous nucleotide was more rapid. 3. Addition of the uncoupling agent carbonyl cyanide phenylhydrazone caused a rapid fall of ATP and a parallel rise in ADP, then ADP was converted into AMP. 4. This was in contrast with rat liver mitochondria endogenous AMP concentrations, which were always lower than those of blowfly mitochondria and changed little under different metabolic conditions. 5. Evidence is presented that adenylate kinase (EC 2.7.4.3) has a dual distribution in blowfly mitochondria, a part being located in the matrix space and a part in the space between the outer and inner mitochondrial membranes, as in liver and other mitochondria. 6. The possible regulatory role of changing AMP concentrations in the mitochondrial matrix was investigated. Partially purified pyruvate carboxylase (EC 6.4.1.1) and citrate synthase (EC 4.1.3.7) were inhibited 30% by 2mm-AMP, whereas pyruvate dehydrogenase (EC 1.2.4.1) was unaffected. 7. AMP activated the NAD(+)-linked isocitrate dehydrogenase (EC 1.1.1.41) activity of blowfly mitochondria in the absence of ADP, but in the presence of ADP, AMP caused inhibition. 8. It is suggested that AMP may exert a controlling effect on the oxidative activity of blowfly mitochondria.
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PMID:Changes in intramitochondrial adenine nucleotides in blowfly flight-muscle mitochondria. 437 97

1. The intracellular location and maximal activities of enzymes involved in phosphoenolpyruvate synthesis have been investigated in pigeon liver. Enolase and pyruvate kinase were cytoplasmic, and the activities were 50-60 and 180-210mumoles/min./g. dry wt. at 25 degrees respectively. Phosphoenolpyruvate carboxykinase was present exclusively, and nucleoside diphosphokinase predominantly, in the mitochondria; the particles had to be disrupted to elicit maximal activities, which were 27-33 and 400-600mumoles/min./g. dry wt. at 25 degrees respectively. The activities of all four enzymes did not change significantly during 48hr. of starvation. 2. Conditions for incubation of washed isolated mitochondria were established, to give high rates of synthesis of phosphoenolpyruvate, linear with time and proportional to mitochondrial concentration. Inorganic phosphate and added adenine nucleotides were stimulatory, whereas added Mg(2+) inhibited, partly owing to activation of contaminant pyruvate kinase. Phosphoenolpyruvate formation occurred from oxaloacetate, malate, fumarate, succinate, alpha-oxoglutarate and citrate, in decreasing order of effectiveness. 3. The steady-state ATP/ADP ratio of mitochondrial suspensions was decreased in the presence of added 2.5mm-Mg(2+) (owing to stimulation of adenylate kinase and possibly of an adenosine triphosphatase), 0.5mm-Ca(2+) or 0.4mm-dinitrophenol. In each case the rate of substrate removal and oxygen uptake was increased, whereas phosphoenolpyruvate synthesis was inhibited. Citrate formation was enhanced, owing to de-inhibition of citrate synthase. These effects were not primarily related to changes in the oxaloacetate concentration. 4. Both phosphoenolpyruvate carboxykinase and nucleoside diphosphokinase were active within the atractylosidesensitive barrier to the mitochondrial metabolism of added adenine nucleotides. There was no correlation between the rate of substrate-level phosphorylation associated with the oxidation of alpha-oxoglutarate, and the synthesis of phosphoenolpyruvate. 5. The results suggest that phosphoenolpyruvate formation in pigeon-liver mitochondria is regulated partly by the phosphorylation state of the adenine and guanine nucleotides, and partly by variations in the oxaloacetate concentration, all in the mitochondrial matrix. 6. Phosphoenolpyruvate is assumed to be the metabolite transported from the mitochondria to the cytoplasm during gluconeogenesis from oxaloacetate in pigeon liver.
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PMID:The regulation of phosphoenolpyruvate synthesis in pigeon liver. 496 63

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

The behavior of several enzymes was studied during rat heart development (4 days before birth to adult stage). Hexokinase has its highest activity during the fetal period; it decreases at birth and remains with low activity in the adult. The alpha-glycerophosphate dehydrogenase and alpha-glycerophosphate oxidase profiles are similar up to the 15th day of development. From there onwards, both profiles diverge, the cytoplasmic activity increasing 3-fold, while the mitochondrial activity remains unchanged. The developmental profiles of the malate dehydrogenases are almost parallel. The development of citrate synthase and succinate dehydrogenase results in a 2- to 4-fold increase in their activities. However, ATPase increases dramatically (20-fold) over the same period. With respect to the enzymes of the adenine nucleotide metabolism, adenylate kinase is fully expressed throughout all ages examined, showing no variation during development. AMP deaminase and creatine kinase increase during development, the cytoplasmic creatine kinase reaching a high level at birth whereas the increases of the mitochondrial enzymes take place gradually during development.
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PMID:Development of enzymes of energy metabolism in rat heart. 623 Jan 12

We studied the effects of running-training, heavy exercise and termination of training on the heart weight, the ratio heart to body weight and the cardiac muscle activities of actomyosin ATPase, citrate synthase, succinate dehydrogenase, cytochrome c oxidase, malate dehydrogenase, adenylate kinase and beta-glucuronidase with adult male NMRI-mice. Stable hypertrophy (6-7%), estimated by the ratio heart or ventricle weight to body weight, was achieved by 28 exercises and it was dependent on the running speed (20 vs. 25 m X min-1). The withdrawal of training for 5-61 days did not permanently decrease the heart weight or the heart to body weight ratio to the level of sedentary controls. The activity of enzymes of energy metabolism or actomyosin ATPase were not affected by training, heavy exercise or terminated training. beta-glucuronidase activity slightly (20-25%) increased in the trained animals and remained at a higher level during the period of terminated training. The results suggest that the capacity for aerobic metabolism of normal mice heart is sufficient to meet the enhanced demand for ATP imposed by running-training and that the heart enlargement occurs in equal proportions with the enzymatic potential of the cardiac tissue.
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PMID:Selected enzyme activities in mouse cardiac muscle during training and terminated training. 623 64

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

An attempt was made to determine the relationship of myoglobin content to specific fiber types in human muscle. Biopsies were obtained from biceps brachii, vastus lateralis, and gastrocnemius muscles of untrained subjects and from the vastus lateralis muscle of a highly trained athlete at peak training and at intervals of no training (detraining). Individual muscle fibers were assayed, by quantitative microanalytical methods, for myoglobin, lactate dehydrogenase, malate dehydrogenase, citrate synthase, beta-hydroxyacyl-coenzyme A dehydrogenase, and adenylokinase activities all on the same fiber. The enzyme levels were used to classify the fibers into type I or II. The results show that the content of myoglobin in human muscle does not differ greatly between fiber types in contrast to other species. The type II fibers contained, on the average, at least two-thirds as much myoglobin as type I fibers. The concentration of myoglobin did not change in either fiber type during detraining (84 days), despite marked changes in lactate dehydrogenase, adenylokinase and the three oxidative enzymes.
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PMID:Myoglobin levels in individual human skeletal muscle fibers of different types. 649 Dec 55


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