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)

The maximum activities of some key enzymes of metabolism were studied in lungs of fed and 48-h-starved rats. The maximum activity of hexokinase in the lung is similar to that of other tissues of the body, but lower than that of phosphorylase and 6-phosphofructokinase. High activities of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were found in lung tissue, suggesting the importance of the pentose phosphate pathway in the lung. The activities of hexokinase and 6-phosphofructokinase were decreased whereas that of phosphorylase increased in response to starvation. Of the enzymes of the tricarboxylic acid cycle whose activities were measured, that of oxoglutarate dehydrogenase was the lowest, yet its activity (approximately 4.2 nmol/min per mg protein at 37 degrees C) was considerably greater than the flux through the cycle (0.46 nmol/min per mg protein at 37 degrees C; calculated from oxygen consumption by incubated lung slices). The activities of both oxoglutarate dehydrogenase and citrate synthase were decreased by starvation. The activities of 3-oxoacid CoA-transferase and acetoacetyl-CoA thiolase were low in lung tissue compared to those of other tissues (eg kidney, brain) and that of 3-hydroxybutyrate dehydrogenase was very low. The activity of carnitine palmitoyl transferase is higher in the lung, suggesting that fatty acids (and possibly acetoacetate) could provide acetyl-CoA as substrate for the tricarboxylic acid cycle. Very low rates of utilization of 3-hydroxybutyrate were observed during incubation of lung slices, but that of oleate was 1.2 nmol/h per mg of protein.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolism of glucose, glutamine, long-chain fatty acids and ketone bodies by lungs of the rat. 176

The activity patterns of enzyme linked to energy transduction are measured as an estimate of the energy potential capacity of the brain during aging. Early investigations provided information on age-related modifications in the apparent activity of these enzymes in the brain as a whole without taking into account the anatomical, morphological, and functional heterogeneity of the discrete brain regions, the metabolic compartments, and their different time course of aging processes. These considerations prompted the investigators to focus their efforts on subcellular organelles, representative of metabolic compartments, isolated from selected brain regions. In the present study, to better elucidate the role of the synaptic compartment during aging, the maximum rate (Vmax) of enzymes involved in energy metabolic pathways is evaluated in synaptosomes isolated from the cerebral cortex of rats aged 4, 12, and 24 months. The potential catalytic activity of phosphofructokinase and citrate synthase is not affected by aging. In contrast, the Vmax of pyruvate dehydrogenase and particularly of cytochrome oxidase decreases in aged rats. A marked increase is found in the Vmax of glucose-6-phosphate dehydrogenase in 24-month-old rats and could support the availability of nicotinamide adenine dinucleotide phosphate (NADPH) for antiperoxidative processes. Pretreatments of the animals with certain drugs are performed in order to check the responsiveness of the tissue and the plasticity of enzyme proteins during aging. Papaverine (acting on macrocirculation) is ineffective, but raubasine (acting on microcirculation and metabolism) and almitrine (acting on oxygen availability) both interfere with the potential activity of some of the enzymes tested. Their influence differs with the age of the animal and are in agreement with their action on brain carbohydrate and phospholipid metabolism.
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PMID:Role of synaptosomal enzymatic alterations and drug treatment in brain aging. 196 31

It has been widely reported that polyunsaturated fatty acids (PU-FA n-6) in the diet lead to immunosuppression. In the present study, the activity of key enzymes several metabolic pathways were measured in the immune tissues of rats fed polyunsaturated (UC) or saturated fatty (SC) acids-rich diets. The following enzyme activities were measured: hexokinase, citrate synthase, glucose-6-phosphate dehydrogenase, glutaminase and malic enzyme. The metabolism of immune tissues was markedly changed by the fat content of the diet. However, UC diet determined more significant metabolic changes than SC diet.
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PMID:Polyunsaturated and saturated fatty acids-rich diets and immune tissues. 2. Maximal activities of key enzymes of glutaminolysis, glycolysis, pentose-phosphate-pathway and Krebs cycle in thymus, spleen and mesenteric lymph nodes. 209 Jan 3

In synaptosomes from rat cerebral cortex, the potential catalytic activity of some enzymes related to energy metabolism--namely, phosphofructokinase and citrate synthase--is not affected by aging. In contrast, the maximum velocity (Vmax) of cytochrome oxidase and of pyruvate dehydrogenase decreases in aged rats. A marked increase is found in the Vmax of glucose 6-phosphate dehydrogenase in aged rats and could be related to the availability of NADPH for antiperoxidative processes. Pretreatments of experimental animals with certain drugs were done to investigate the plasticity of enzyme proteins during aging. Papaverine, which acts on macrocirculation, is ineffective, but delta-yohimbine acting on microcirculation and metabolism and almitrine acting on oxygen availability both could interfere with the potential activity of some enzymes. However, their influence differs with the age of the rats.
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PMID:Age-related modification of enzyme activities in synaptosomes isolated from rat cerebral cortex. 254 Mar 42

Regional glucose uptake in perfused hearts, and the activities of several glycolytic enzymes contributing to the glucose metabolism in perfused and nonperfused hearts were studied in male and female rats after 8-9 weeks of swimming training. The left ventricular glucose uptake showed a transmural gradient in the sedentary animals, the subendocardial uptake being 30% and 12% higher than that of the subepicardial layer in the males and females, respectively. Swimming exercise abolished the left ventricular glucose uptake gradient in male rats, and in female rats an opposite gradient was found, the subepicardial uptake being 23% higher than the subendocardial uptake. The activities of phosphofructokinase and 3-phosphoglyceraldehyde dehydrogenase also showed transmural gradients in the left ventricles. Training did not abolish these gradients. Training-induced changes in the activities of phosphofructokinase, 3-phosphoglyceraldehyde dehydrogenase, pyruvate kinase, lactate dehydrogenase, glucose-6-phosphate dehydrogenase, citrate synthase, and malate dehydrogenase were found in certain sites of the myocardium. Perfusion of isolated hearts for 50 min with insulin-containing Krebs-Ringer buffer especially affected the activities of phosphofructokinase, lactate dehydrogenase, and citrate synthase, increasing these activities in the left ventricles and decreasing them in the atria. These results indicate that there are regional differences between male and female rats in the cardiac glucose uptake rate after swimming training.
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PMID:Effect of chronic exercise on glucose uptake and activities of glycolytic enzymes measured regionally in rat heart. 273 May 24

A method for a 50-60-fold purification of a cysteine proteinase from trophozoites of Entamoeba histolytica using 35-80% ammonium sulphate fractionation, gel chromatography on Sephadex G-75, and preparative isoelectric focusing is described. The enzyme was examined for its proteolytic potencies towards native enzyme substrates. The amebic proteinase directly inactivates aldolase and glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle as well as glucose-6-phosphate dehydrogenase from yeast. The inactivation of citrate synthase from porcine heart proceeds rather slowly, whereas malate dehydrogenase from porcine heart is not affected by the amebic proteinase under the condition used. With the exception of aldolase all inactivated enzyme substrates have been cleaved by limited proteolyses yielding major cleavage products. The inactivation of aldolase probably functions by the release of a small segment from a terminus being essential for aldolase activity.
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PMID:Cysteine proteinase of Entamoeba histolytica. I. Partial purification and action on different enzymes. 287 Apr 30

Twenty adult Sprague-Dawley outbred rats (10 male and 10 female) were fed a nonpurified diet without or containing dehydroepiandrosterone acetate (DHEA 6 g/kg diet) for 11 w. DHEA-treated animals weighed less than the controls after 6 wk and until the end of treatment. However, only the differences between male groups were statistically significant. Food intake of the DHEA-fed animals was not affected, but resting heat production was elevated for both sexes. Serum triglyceride levels and activity of hepatic glucose-6-phosphate dehydrogenase of the experimental groups were lower than controls. Analyses of body composition indicated DHEA-treated animals had proportionately less body fat and therefore more body water, protein and ash than controls. In most cases, differences in body composition were due primarily to effects of DHEA on the female animals. In a second experiment, DHEA treatment did not alter urinary ketone levels nor did it enhance citrate synthase activity in interscapular brown fat, skeletal muscle, heart or liver. Findings suggest that DHEA acetate treatment affected body weight, body composition and utilization of dietary energy by both impairing fat synthesis and promoting fat-free tissue deposition and resting heat production. Possible mechanisms by which DHEA may affect metabolism are discussed.
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PMID:Effects of dehydroepiandrosterone acetate on metabolism, body weight and composition of male and female rats. 294 8

The evaluation of the specific activity of some enzymes related to energy transduction was performed in 7 fresh samples of malignant gliomas and in 4 samples of normal brain tissue. Compared with normal brain tissue, the hexokinase, phosphofructokinase and citrate synthase activities are lower; the lactate dehydrogenase and succinate dehydrogenase are unchanged, while glucose-6-phosphate dehydrogenase and NADP+-isocitrate dehydrogenase activities are higher in gliomas.
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PMID:Enzymes related to energy metabolism in human gliomas. 294 16

The fatigue characteristics and the activities of oxidative and glycolytic enzymes were determined in tetrodotoxin (TTX)-induced disuse muscles and in muscles of animals recovering from TTX-induced disuse (TTX-rec). In addition, the effects of additional daily exercise (grid-climbing and swimming) on the fatigue and metabolic profiles of muscles from TTX-rec and control animals were investigated. The activities of citrate synthase (CS), phosphofructokinase (PFK), and alpha-glycerophosphate dehydrogenase (alpha-GPD) were depressed following 28 days of inactivity produced by the chronic neural application of TTX. The response of these muscles to a pattern of stimulation that has been used to classify fast-twitch motor units according to their fatigability (6) (330 ms, 40 Hz, l/s, 4 min) was not affected to any great extent by inactivity, except for a loss in the ability to summate or maintain forces during each 330-ms burst, as fatigue developed. After 28 days of recovery, the concentration of CS had returned to normal, whereas the concentrations of PFK and alpha-GPD remained depressed. TTX-rec muscles, on the other hand, appeared more resistant to fatigue than control muscles, based on several indices of muscle fatigue. Control and TTX muscles responded similarly to daily training. Swimming but not climbing increased the activity of CS and the fatigue resistance of the muscle. Neither exercise influenced the activity of PFK and alpha-GPD. Although the activity of CS was influenced by the level of neuromuscular usage, the former did not appear to play a dominant role in determining the fatigue resistance of the muscle, emphasizing the need to consider other factors as primary determinants of muscle fatigue.
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PMID:Recovery of muscle from tetrodotoxin-induced disuse and the influence of daily exercise. 2. Muscle enzymes and fatigue characteristics. 297 Sep 77

Hepatocytes were prepared from 15 degrees C acclimated catfish (Ictalurus punctatus) and maintained in primary culture for 20 days on biomatrix at 7, 15, and 25 degrees C without hormones or serum to determine if cells can directly adapt to temperature. Specific activities of cytochrome-c oxidase, NADH-cytochrome c reductase, citrate synthase, and glucose-6-phosphate dehydrogenase showed acclimatory rate compensation (7 greater than 15 greater than 25 degrees C cultured); 6-phosphogluconate dehydrogenase had activity changes of 15 greater than 7 greater than 25 degrees C cultured; activity of lactate dehydrogenase occurred in the series 7 greater than 15 = 25 degrees C. Protein synthesis of freshly isolated hepatocytes from catfish acclimated to the three temperatures exhibited acclimatory rate compensation. In contrast, protein synthesis of cultured hepatocytes occurred in the series 15 greater than 25 greater than 7 degrees C cultured. Protein degradation was highest at 25 degrees C followed by cells at 15 and 7 degrees C. Cultured hepatocytes showed incomplete temperature acclimation in vitro by way of enzyme activity changes and of protein synthesis. This suggests that some factor(s), such as hormones, is probably necessary to mediate the full temperature-acclimation process.
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PMID:Can cultured teleost hepatocytes show temperature acclimation? 300 35


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