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)

The purpose of this study was to investigate alterations in structural and functional properties in the soleus (SOL) and extensor digitorum longus (EDL) muscles of rats after 1, 2, and 5 wk of tail suspension. Maximal O2 uptake was 19% lower after 5 wk suspension. Loss of muscle mass was greater in SOL (63%) than in EDL (22%) muscle. A reduction of type I distribution was accompanied by an increase of intermediate fiber subgroups (int I in SOL, int II in EDL). The cross-sectional area of all three fiber types was reduced by hypokinesia. The decrease in capillaries per fiber in SOL was greater than the decrease in citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities after 5 wk. No alteration in lactate dehydrogenase activity was noted. In EDL, no changes in fiber area, capillarization, and enzymatic activities occurred. Energy charge remained unchanged (0.91) whatever the muscle. These results suggest that type I fibers showed an earlier and greater susceptibility than type II fibers to suspension which is also accompanied by a decreased aerobic capacity.
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PMID:Structural and functional responses to prolonged hindlimb suspension in rat muscle. 365 14

The capacity for energy production was evaluated in male, Fischer 344 rats as they advanced from adulthood through senescence. At 10 months of age, the animals were divided into three groups: sedentary, fed ad libitum (S); exercised by treadmill running, fed ad libitum (E); and sedentary, caloric restricted by alternate day feeding (R). Activities of selected enzymes, ADP-stimulated respiration and levels of cytochromes, were determined in homogenates of liver and gastrocnemius muscle prepared from young controls (10-month old S) and 18-, 24-, and 30-month old animals. In liver, age-linked decrements were found in the activities of 3-hydroxyacyl-CoA dehydrogenase (S, E, and R) and citrate synthase (S), and in cytochrome c content (S and E), whereas substrate-catalysed oxidations were unaffected. In the gastrocnemius muscle (S, E, and R), respiration, activities of enzymes of the Krebs cycle and glycolysis, and cytochrome content were decreased after the age of 18 months. Oxidative capacity was increased in muscle through exercise (about 40%) and in liver by food restriction (about 20%). Body and soleus muscle mass declined similarly in all groups (about 14% from 30 to 18 months of age), whereas the loss of weight in the gastrocnemius muscle was much greater (34%). The data indicate that energy metabolism in the senescent animal is competent to meet its needs and age-related declines in energy metabolism are secondary to the aging process.
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PMID:Bioenergetics in the aging Fischer 344 rat: effects of exercise and food restriction. 366 72

The purpose of this study was to compare the effects of spontaneous recovery or recovery by treadmill training (180 min/day, 5 days/wk, 30 m/min for 8 wk) on maximal O2 uptake (VO2max), histochemical and biochemical muscular properties (soleus), of rats subsequent to 5 wk of hindlimb suspension. Spontaneous recovery reversed the 15% reduction in VO2max, whereas training posthypokinesia induced a 20% increase over control values. In the spontaneous recovery group, both citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities, decreased by hypokinesia (-40%), increased but remained 20% below the control level. In the training posthypokinesia group, an increase of these activities over control occurred (+50 and +20%, respectively). Recovery or training led to a 100% type I distribution in soleus muscle and to a recovery of all fibers' cross-sectional areas. In the spontaneous recovery group, capillaries per fiber, decreased by 46%, returned to the normal range. In the training posthypokinesia group, training induced an increase in capillaries per fiber above their control values (+23%). These results point to the plasticity of the muscle and indicate the necessity of a posthypokinesia training program for recovery of the total oxidative enzyme capacity.
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PMID:Effect of spontaneous recovery or retraining after hindlimb suspension on aerobic capacity. 369 9

The superficial muscle fibres in the proximal part of the closer muscle in the crab Eriphia can be separated into four fibre groups (I-IV) on the basis of electrophysiological and histochemical characteristics. The activity levels of glyceraldehydephosphate dehydrogenase (GAPDH), lactate dehydrogenase (LDH), citrate synthase (CS), NADP-isocitrate dehydrogenase (IDH) and 3-hydroxyacyl-CoA dehydrogenase (HAD), determined in single electrophysiologically identified fibres, differed significantly among the different fibre groups. In addition, fibres belonging to the same group, with similar electrophysiological characteristics, demonstrated variability with regard to metabolic enzyme activities. Nevertheless, comparison of absolute enzyme activities and enzyme activity ratios permitted the discrimination of at least three groups. These groups corresponded with those defined according to electrophysiological and histochemical characteristics. The group I fibres (tonic fibres) are intermediate in oxidative potential and show the lowest values of glycolytic enzymes. The group II and group III fibres can be regarded as fast oxidative fibres. The high ratio between activity levels of enzymes for glycolytic and oxidative metabolism found for group IV fibres (fast fibres) demonstrated that this group depends strongly on anaerobic metabolism.
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PMID:Enzyme activities in single electrophysiologically identified crab muscle fibres. 370 50

The present study examines the effect of the acetylenic thioester dec-2-ynoyl-CoA (delta 2 10 identical to 1-CoA) on the microsomal fatty acid chain elongation pathway in rat liver. When the individual reactions of the elongation system were measured in the presence of delta 2 10 identical to 1-CoA, the trans-2-enoyl-CoA reductase activity was markedly inhibited (Ki = 2.5 microM), whereas the activities of the condensing enzyme, the beta-ketoacyl-CoA reductase, and the beta-hydroxyacyl-CoA dehydrase were not affected. The absence of inhibition of total microsomal fatty acid elongation was attributed to the significant accumulation of the intermediates, beta-hydroxyacyl-CoA and trans-2-enoyl-CoA, without formation of the saturated elongated product, indicating that the trans-2-enoyl-CoA reductase-catalyzed reaction was the only site affected by the inhibitor. The nature of the inhibition was noncompetitive. In contrast to the delta 2 10 identical to 1-CoA, delta 3 10 identical to 1-CoA did not inhibit trans-2-enoyl-CoA reductase activity, suggesting that the mode of inhibition was not via formation of the 2,3-allene derivative. Based on the observation (a) that p-chloromercuribenzoate markedly inhibits reductase activity, (b) that dithiothreitol protects the enzyme against inactivation by delta 2 10 identical to 1-CoA, (c) of the spectral manifestation of the interaction between thiol reagents and delta 2 10 identical to 1-CoA depicting an absorbance peak similar to that of the beta-ketoacyl thioester-Mg2+ enolate complex, (d) of a similar absorbance spectrum formed by the interaction between delta 2 10 identical to 1-CoA and liver microsomes, and (e) of the absence of formation of a similar spectrum by delta 3 10 identical to 1-CoA, trans-2-10:1-CoA, or delta 2 10 identical to 1 free acid with liver microsomes, we propose that delta 2 10 identical to 1-CoA inactivates trans-2-enoyl-CoA reductase by covalently binding to a critical sulfhydryl group at or in close proximity to the active site of the enzyme.
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PMID:Site of inhibition of rat liver microsomal fatty acid chain elongation system by dec-2-ynoyl coenzyme A. Possible mechanism of inhibition. 375 85

3-Hydroxyacyl coenzyme A (CoA) dehydrogenase-binding protein was solubilized from inner mitochondrial membrane by using taurodeoxycholate at high ionic strength. The binding protein was isolated from the suspension using 3-hydroxyacyl-CoA dehydrogenase affinity chromatography. The protein eluted from the affinity column had a molecular weight of approximately 150,000, as determined by gel filtration. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the protein is a dimer consisting of 69,000 and 71,000 molecular weight subunits. The enzyme binding capacity of this protein was tested with a polyethylene glycol precipitation method: 0.5 mg of enzyme could be precipitated together with 1 mg of binding protein, showing that 1 mol of binding protein binds 1 mol of enzyme. This protein had no affinity toward malic dehydrogenase, citrate synthase, and fumarase. The approximately 2-fold increase in the 3-hydroxyacyl-CoA dehydrogenase activity when it was measured in the presence of the binding protein is additional evidence of enzyme-binding protein interaction. When incorporated into liposomes, the binding protein retained its ability to bind 3-hydroxyacyl-CoA dehydrogenase, but did not bind malic dehydrogenase, citrate synthase, and fumarase. These results suggest that the protein isolated by us has a specific function in anchoring a beta-oxidation enzyme to the matrix surface of the mitochondrial membrane.
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PMID:Isolation and characterization of 3-hydroxyacyl coenzyme A dehydrogenase-binding protein from pig heart inner mitochondrial membrane. 377 31

The paired tracer-dilution method applied to the rat hindlimb perfusion technique was used to investigate the effect of a 10-wk treadmill training program on glucose transport and net uptake in rat skeletal muscles. Glycolytic and oxidative marker enzyme activities were determined. The rats were allowed to rest for 2 days before the experiments were carried out, since long-term adaptive changes were to be studied. The endurance training program caused a 30% increase in the 3-hydroxyacyl-CoA dehydrogenase and citrate synthase activities, but no changes in glycolytic enzymes, confirming that endurance training provokes an increase in the oxidative capacity of the muscle. No significant differences were found in glucose transport rate or net glucose uptake between trained and sedentary rats, which indicates that no long-term adaptive changes in glucose utilization occur in response to endurance training.
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PMID:Influence of endurance training on glucose transport and uptake in rat skeletal muscle. 377 98

Inter- and subscapular brown adipose tissue depots were removed from nine female Osborne-Mendel rats. These lipectomized animals and nine sham-operated controls recovered from surgery for 7 days at 25 degrees C and were then placed on a highly palatable liquid diet. All animals were maintained for a 2nd wk at 25 degrees C before being switched to 8 degrees C. After 9 wk in the cold, animals were killed, and the brown adipose tissue was dissected from scapular, cervical, thoracic, perirenal, and axillary regions. Total brown fat pad mass, protein content, brown adipocyte number, citrate synthase activity, and beta-hydroxyacyl CoA dehydrogenase activity in each of the dissected brown fat depots were significantly less than those of the sham-operated controls. Thus there was incomplete metabolic compensation in the remaining brown fat depots after the removal of the scapular brown fat in the lipectomized rats. The mass and lipid content of the retroperitoneal white adipose depot were significantly increased in the lipectomized rats as was their carcass fat content (up 14%). Food intake of the lipectomized rats was slightly but significantly decreased. These data indicate that a reduction in the amount of functional brown fat is accompanied by increased body fat accretion and are thus consistent with the hypothesis that decreased brown adipose thermogenesis can lead to altered energy balance and increased white fat deposition.
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PMID:Brown adipose tissue lipectomy leads to increased fat deposition in Osborne-Mendel rats. 397 Feb 38

The effects of training on skeletal muscle composition were studied in four Standardbred geldings given a seven week submaximal treadmill training programme. Before the start of training, muscle biopsies were collected from the left middle gluteal muscle for the determination of muscle fibre types, oxidative capacity and capillary numbers using histochemical techniques. The concentrations of citrate synthase, 3-hydroxyacyl-CoA dehydrogenase (HAD), lactate dehydrogenase and total muscle glycogen were measured using fluorometric methods. Muscle biopsy samples were repeated after one, three, five and seven weeks of training and the same measurements performed. No significant changes were found in muscle fibre types or capillary numbers as a result of training, although there was an increase in the oxidative capacity of the Type IIB fibres after seven weeks training. After seven weeks of training there were also increases in the concentrations of citrate synthase and HAD and a decrease in lactate dehydrogenase. Before commencement of training the horses underwent a standardised submaximal exercise test and muscle glycogen concentrations were measured before and immediately after the exercise. This procedure was repeated after one, three, five and seven weeks of training. A progressive decrease in the rate of glycogen utilisation occurred throughout the period of training, which by seven weeks was 36 per cent lower than that before training.
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PMID:Effects of a submaximal treadmill training programme on histochemical properties, enzyme activities and glycogen utilisation of skeletal muscle in the horse. 407 45

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


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