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)

Experiments were performed on eight subjects affected by peripheral arterial occlusive disease (PAOD) of the lower limbs. Each patient was submitted to Ecodoppler, angiography and the "Treadmill test". Two bioptic muscle of these patients. A sample was used for the spectrophotometric and spectrophotofluorimetric determinations of: glycogen, pyruvate, lactate, citrate, alpha-ketoglutarate, malate, aspartate, glutamate, AMP, ADP, ATP and creatine phosphate (CP). The other bioptic sample was used to determine the following enzyme activities: hexokinase, phosphofructokinase, pyruvate kinase, lactate dehydrogenase, citrate synthase, succinate dehydrogenase, malate dehydrogenase, total NADH cytochrome c reductase, cytochrome oxidase, aspartate aminotransferase and alanine aminotransferase. Patients showed an increase in lactate dehydrogenase, total NADH cytochrome c reductase and succinate dehydrogenase activities, a decrease in glycogen, ATP and CP concentrations. Telethermographic data showed patient muscle thermic emission quantitatively different from control group. The telethermographic test can be used as an additional diagnostic tool to determine and monitor the efficiency of a muscle undergoing metabolic failure.
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PMID:Instrumental and metabolic evaluation of patients affected by peripheral arterial occlusive disease (PAOD) following surgical revascularization surgery. 928 78

The activity of glycolytic and oxidative enzymes was monitored in the white muscle of Atlantic cod Gadus morhua experiencing different growth rates. A strong positive relationship between the activity of two glycolytic enzymes and individual growth rate was observed regardless of whether the enzyme activity was expressed as units per gram wet mass, units per gram dry mass or with respect to muscle protein and DNA content. The most sensitive response to growth rate was observed when pyruvate kinase and lactate dehydrogenase activities were expressed as units per microgram DNA, and this may be useful as an indicator of growth rate in wild fish. In contrast, no relationship between the activities of oxidative enzymes and growth rate was observed when cytochrome c oxidase and citrate synthase activities were expressed as units per gram protein. Apparently, the aerobic capacity of white muscle in cod is not specifically increased to match growth rate.
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PMID:How should enzyme activities be used in fish growth studies? 931 92

Glucose, the most potent insulin secretagogue, stimulates insulin secretion by aerobic glycolysis, but other secretagogues stimulate insulin release exclusively by mitochondrial metabolism. It is well known that in the intact pancreatic beta-cell, either kind of secretagogue can induce oscillations in metabolism (e.g., glycolysis, ATP/ADP, NAD(P)/NAD(P)H ratios) that occur with a periodicity similar to oscillations in membrane electrical potential and insulin secretion. In this study, pancreatic islet cytosol or mitochondrial fractions were incubated in the presence of physiological concentrations of substrates. Repeated additions of physiological effectors caused oscillations in the activities of the three enzymes studied. Succinate dehydrogenase activity in islet mitochondrial extracts was made to oscillate by adding oxaloacetate (5 micromol/l) to inhibit the enzyme. The enzyme was reactivated by adding acetyl-CoA (3 micromol/l), which combines with oxaloacetate in the citrate synthase reaction and lowers the concentration of oxaloacetate, thus beginning another oscillation. Pyruvate kinase activity was made to oscillate by adding fructose bisphosphate (10 micromol/l). Fructose bisphosphate was degraded to triose phosphates fairly rapidly, and, as it was degraded, there was a parallel decrease in pyruvate kinase activity. The enzyme was reactivated and made to oscillate with subsequent additions of fructose bisphosphate. The mitochondrial glycerol phosphate dehydrogenase was made to oscillate by adding EGTA to chelate calcium, which activates the enzyme. When the concentration of free calcium was raised to >0.1 micromol/l by adding more calcium, the activity of the enzyme increased. Repeated additions of chelator and calcium caused the enzyme activity to oscillate. The results with these three enzymes and physiological concentrations of naturally occurring effectors raise the possibility that the activities of not only these enzymes but of numerous enzymes oscillate in vivo in response to levels of allosteric effectors and substrates. If this is the case, pacemaker activity may result from complex effects distributed across multiple regulatory sites in both the cytosol and mitochondria, rather than from a single enzyme acting as a primary pacemaker.
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PMID:Oscillations in activities of enzymes in pancreatic islet subcellular fractions induced by physiological concentrations of effectors. 939 86

Mammalian hibernation requires specific regulatory controls on metabolism to coordinate entry, maintenance, and arousal stages, as well as adjustments to many metabolic functions to support long-term dormancy. Several mechanisms of metabolic regulation are involved in potentiating survival. One of these is the reversible phosphorylation of regulatory enzymes, including glycogen phosphorylase, phosphofructokinase, pyruvate kinase, and pyruvate dehydrogenase. In particular, the sharp suppression of pyruvate dehydrogenase during hibernation shows the importance of control over mitochondrial oxidative metabolism for reducing metabolic rate. Fine control over specific enzymes also occurs via differential temperature effects on kinetic and allosteric properties. Analysis of temperature effects on the properties of pyruvate kinase, fructose-1,6-bisphosphatase, creatine kinase, and citrate synthase from ground squirrel or bat tissues shows a range of responses, some that would reduce enzyme activity in the hibernating state and some that would promote temperature-insensitive enzyme function. Reduced tissue phosphagen and adenylate levels, but not energy charge, may also contribute to overall metabolic suppression. New research is exploring the role of transcriptional and translational controls in hibernation via several approaches. For example, immunoblotting with antibodies to heat shock proteins (hsp 70 family) revealed the presence of constitutive hsc 70 in bat tissues but levels of the protein did not change between euthermic and hibernating states and neither the inducible hsp 70 nor the glucose-responsive protein grp 78 appeared during hibernation.
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PMID:Metabolic regulation in mammalian hibernation: enzyme and protein adaptations. 950 21

We examined the morphometric and biochemical effects of ventricular hypertrophy in male rainbow trout (Oncorhynchus mykiss) during sexual maturation. Our investigation focused on characterizing the growth of ventricular layers, on cardiomyocyte dimensions (length, cross-sectional area and cell volume) and on the activities of enzymes involved in intermediary metabolism. Relative ventricle mass (100 x ventricle mass/body mass) increased by as much as 2.4-fold during sexual maturation [as defined by an increasing gonadosomatic index (100 x gonad mass/body mass)], and this resulted in an increased proportion of epicardium relative to endocardium. Ventricular enlargement was associated with increased length (+31 %) and transverse cross-sectional area (+83 %) of cardiomyocytes, which resulted in an expansion of up to 2.2-fold in mean myocyte volume (from 1233 to 2751 micron3). These results indicate that sexual maturation induces ventricular enlargement through myocyte hypertrophy. Cell length and cross-sectional area were similar in both myocardial layers, and myocytes were elliptical rather than circular in transverse cross section. Ventricular hypertrophy did not alter transverse cell shape, perhaps reflecting the maintenance of short diffusion distances for small molecules as cells hypertrophy. Myocyte hypertrophy could not account entirely for the sevenfold range of ventricle masses from different-sized fish, indicating that myocyte hyperplasia contributes substantially to ventricular growth as trout grow. Measurements of the maximal activities of metabolic enzymes demonstrated that ventricular hypertrophy was associated with (1) higher epicardial but not endocardial activities of citrate synthase (by 23 %) and beta-hydroxyacyl-CoA dehydrogenase (by 20 %); (2) lower activities of hexokinase (by 50 %) in both layers, and (3) no change in lactate dehydrogenase or pyruvate kinase activities, which were also similar between layers. These results suggest that the energetic needs of the hypertrophied trout ventricle may be met through increased reliance on fatty acid oxidation, particularly by the endocardium, but decreased reliance on glucose as a metabolic fuel in both layers.
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PMID:Morphometric and biochemical characteristics of ventricular hypertrophy in male rainbow trout (Oncorhynchus mykiss). 955 37

Muscle deconditioning is a common observation in patients with congestive heart failure (CHF), chronic obstructive pulmonary disease, neuromuscular diseases or prolonged bed rest. To gain further insight into metabolic and mechanical properties of deconditioned slow-twitch (soleus) or fast-twitch (EDL) skeletal muscles, we induced experimental muscle deconditioning by hindlimb suspension (HS) in rats for 3 weeks. Cardiac muscle was also studied. Besides profound muscle atrophy, increased proportion of fast type II fibers as well as fast myosin isoenzymes, we found decreased calcium sensitivity of Triton X-100 skinned fiber bundles of soleus muscle directed towards the fast muscle phenotype. Glycolytic enzymes such as hexokinase and pyruvate kinase were increased, and the LDH isoenzyme pattern was clearly shifted from an oxidative to an anaerobic profile. Creatine kinase (CK) and myokinase activities were increased in HS soleus towards EDL values. Moreover, the M-CK mRNA level was greatly increased in soleus, with no change in EDL. However, oxygen consumption rate assessed in situ in saponin skinned fibers (12.5 +/- 0.8 in C and 15.1 +/- 0.9 micromol O2/min/g dw in HS soleus compared to 7.3 +/- 1.3 micromol O2/min/g dw in control EDL), as well as mitochondrial CK (mi-CK) and citrate synthase activities, were preserved in HS soleus. Following deconditioning no change in Km for ADP of mitochondrial respiration, either in the absence (511 +/- 92 in C and 511 +/- 111 microM in HS soleus compared to 9 +/- 4 microM in control EDL) or presence of creatine (88 +/- 10 in C and 95 +/- 16 microM in HS soleus compared to 32 +/- 9 microM in control EDL), was found. The results show that muscle deconditioning induces a biochemical and functional slow to fast phenotype transition in myofibrillar and cytosolic compartments of postural muscle, but not in the mitochondrial compartment, suggesting that these compartments are differently regulated under conditions of decreased activity.
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PMID:Muscle unloading induces slow to fast transitions in myofibrillar but not mitochondrial properties. Relevance to skeletal muscle abnormalities in heart failure. 992 74

The activities of pyruvate kinase (PK), pyruvate: formate-lyase (PFL), pyruvate dehydrogenase (PDH), and citrate synthase (CS) involved in the anaerobic glycerol conversion by Klebsiella pneumoniae were studied in continuous culture under conditions of steady states and sustained oscillations. Both the in vitro and in vivo activities of PK, PFL, and PDH are strongly affected by the substrate concentration and its uptake rate, as is the in vitro activity of CS. The flux from phosphoenolpyruvate to pyruvate is found to be mainly regulated on a genetic level by the synthesis rate of PK, particularly at low substrate concentration and low growth rate. In contrast, the conversion of pyruvate to acetyl-CoA is mainly regulated on a metabolic level by the in vivo activities of PFL and PDH. The ratio of in vitro to in vivo activities is in the range of 1 to 1.5 for PK, 5 to 17 for PFL and 5 to 80 for PDH under the experimental conditions. The regulation of in vivo activity and synthesis of these enzymes is sensitive to fluctuations of culture conditions, leading to oscillations of both the in vitro and in vivo activities. In particular, PFL is strongly affected during oscillations; its average in vitro activity is only about half of its corresponding steady-state value under similar environmental conditions. The average in vitro activities of PDH and PK under oscillations are close to their corresponding steady-state values. In contrast to all other enzymes measured for the glycerol metabolism by K. pneumoniae PFL and PDH are more effectively in vivo utilized under oscillations than under steady state, underlining the peculiar role of pyruvate metabolism in the dynamic responses of the culture.
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PMID:Kinetic, dynamic, and pathway studies of glycerol metabolism by Klebsiella pneumoniae in anaerobic continuous culture: IV. Enzymes and fluxes of pyruvate metabolism. 1009 70

The activities of oxidative and glycolytic enzymes show body size-dependent relationships across a wide variety of taxa; however, the mechanistic basis remains unknown. We sampled white epaxial muscle from rainbow trout (Oncorhynchus mykiss) spanning a 100-fold range in body mass. We measured activities of enzymes from aerobic and anaerobic metabolic pathways, RNA [total RNA and mRNA, pyruvate kinase (PK), citrate synthase (CS), and MyoD mRNA], and total DNA. Total RNA and DNA showed a biphasic relationship with body size, with a break point occurring after fish reached 1 yr of age. In contrast, total RNA/total DNA was constant across the entire size range. Neither CS activity nor CS mRNA levels scaled with body mass. PK activity and PK mRNA levels increased in parallel in yearling fish only (r(2) = 0.91, P < 0.01). This suggests that although PK expression is transcriptionally regulated in yearlings, the molecular mechanisms regulating expression change with growth and age. This was supported by a positive correlation between MyoD and PK mRNA levels (r(2) = 0.17, P < 0.05).
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PMID:Allometric scaling of RNA, DNA, and enzyme levels: an intraspecific study. 1051 58

The effects of cell age on metabolism in the nucleated red blood cells of rainbow trout (Oncorhynchus mykiss) were examined. Red blood cells were separated according to age using fixed-angle centrifugation. The mean erythrocyte haemoglobin concentration in old red blood cells was found to be 120 % of that in young red blood cells. In young red blood cells, the activities of the mitochondrial enzymes citrate synthase and cytochrome oxidase were 135-200 %, respectively, of those measured in old red blood cells. The activity of the glycolytic enzyme lactate dehydrogenase in young red blood cells was 170 % of that in old red blood cells, whereas the activity of the glycolytic enzyme pyruvate kinase was not significantly affected by cell age. In addition, young red blood cells consumed over twice as much O(2) and devoted 50 % more O(2) to protein synthesis and the activity of Na(+)/K(+)-ATPase than old red blood cells. Red blood cell age did not significantly affect the rate of lactate production. This study shows that ageing in rainbow trout nucleated red blood cells is accompanied by a significant decline in aerobic energy production and the processes it supports, as well as a corresponding increase in the glycolytic contribution to metabolism.
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PMID:The effects of cell ageing on metabolism in rainbow trout (Oncorhynchus mykiss) red blood cells. 1068 63

Aging affects the metabolic capacity of skeletal muscle, in particular the glycolytic and respiratory capacities. The purpose of this study was to quantify biochemical alterations due to aging in muscular metabolic capacity in human skeletal muscles in sedentary subjects. The activities of various marker enzymes and metabolites related to glycolysis, Krebs' cycle and the electron transfer chain and high energy phosphate compounds were measured in muscle biopsies from the rectus abdominis, vastus lateralis, and gluteus maximus muscles of 76 sedentary subjects (32 males and 44 females) between 15 and 91 yr. No significant differences between males and females were found, but changes related to age were: a decrease in hexokinase and lactate dehydrogenase activities in the rectus abdominis; a decrease in citrate synthase activity and citrate in the vastus lateralis; an increase in pyruvate kinase activity and a decrease in ATP and creatine phosphate concentrations in the gluteus maximus. These data suggest that distinct muscles may respond differently to aging regardless of sex in sedentary subjects.
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PMID:The effects of aging on enzyme activities and metabolite concentrations in skeletal muscle from sedentary male and female subjects. 1070 43


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