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)

In the rat kidney, NaK-ATPase activity increased between days 19 and 20 of gestation (+50%) and between 1 and 24 h after birth (+20%), requiring an increased energy supply. In order to determine whether mitochondrial changes were involved, renal mitochondrial development was investigated from day 19 of gestation to 1 day after birth. Slot-blot analyses of mitochondrial-DNA/nuclear-DNA ratio and determination of citrate synthase activity showed a doubling in the mitochondrial pool between days 19 and 20 of gestation. In isolated mitochondria, oxygen consumption remained unchanged between days 19 and 20 of gestation, and then it was enhanced between days 20 and 21 of gestation (+70%) and between 1 and 24 h after birth (+50%). We also focused on one of the respiratory-chain complexes, ATP synthase, and measured its activity and content during the perinatal period. We demonstrated increases in both activity and content of ATP synthase between days 20 and 21 of gestation and between 1 and 24 h after birth, thus suggesting that changes in ATP synthase activity are ascribed to an increase in the mitochondrial density of ATP synthase complexes. Moreover, the mitochondrial ATP/ADP ratio only increased between 1 and 24 h (+90%), indicating a critical step in the renal respiratory-chain maturation at that time. We therefore conclude that the postnatal enhancement of renal mitochondrial oxidative capacity might depend on protein synthesis de novo and on changes in the adenine nucleotide concentrations.
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PMID:Perinatal maturation of rat kidney mitochondria. 783 86

Erectile function (erection and detumescence) involves the complex interaction of direct neuronal stimulation of corporal smooth muscle, neurohumoral release of specific endothelial contractile and relaxant factors, and secondary modulation by a variety of putative neuropeptides and vasoactive modulators. The net result is a rapid and sustained relaxation of the smooth muscle elements during erection and contraction of the smooth muscle during detumescence. Proper function of the corporal tissue is dependent upon cellular metabolism of glucose and the generation of cellular energy in the form of high energy phosphates. The current study characterizes the following metabolic parameters of the rabbit corpus cavernosum: Tissue concentrations of creatine phosphate (CP), ATP, ADP, and AMP; maximal rate of glucose metabolism to lactic acid and CO2; and activities of the enzymes creatine kinase (CK), citrate synthase, and malate dehydrogenase. For comparative purposes only, bladder smooth muscle preparations were analyzed simultaneously with and under the same conditions as the corpus cavernosum. The results are as follows: The concentrations of ATP and CP in the corpora were significantly lower than the concentrations in bladder. In the corpora, the tissue concentration of CP was lower than the tissue concentration of ATP, whereas the concentration of CP in the bladder was higher than the concentration of ATP. The rate of glucose metabolism to lactic acid and to carbon dioxide was similar for both bladder smooth muscle and corpus cavernosum. The maximal enzymatic activity of the mitochondrial enzyme citrate synthase was similar for both tissues; similarly, there was no significant difference in the activity of malate dehydrogenase between the two tissues.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolic studies on the rabbit corpus cavernosum. 828 87

The conditions of treatment of human skeletal muscle fibers from M. vastus lateralis with saponin were optimized to achieve complete permeabilization of cell membrane at intact mitochondrial oxidative phosphorylation. After 30 min of incubation with saponin all lactate dehydrogenase, 50% of creatine kinase, 30% of adenylate kinase and less than 20% of citrate synthase was released into the permeabilization medium. These skinned fibers behave similar to isolated mitochondria from human skeletal muscle: (i) the respiration with mitochondrial substrates can be stimulated by ADP, (ii) inhibited by carboxyatractyloside and (iii) it is possible to detect fluorescence changes of mitochondrial NAD(P)H on additions of substrates, uncoupler and cyanide. From a comparison of rates of respiration per cytochrome aa3 content of isolated human skeletal muscle mitochondria and saponin-skinned muscle fibers it was possible to calculate that almost 85% of mitochondria in those fibers are accessible for the investigation of oxidative phosphorylation. As shown by the investigation of biopsy samples of two patients with undefined myopathies these fibers are a suitable object for the replacement of isolated mitochondria in the diagnosis of mitochondrial myopathies and encephalomyopathies.
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PMID:Functional characterization of mitochondrial oxidative phosphorylation in saponin-skinned human muscle fibers. 834 61

1. Subsarcolemmal and interfibrillar mitochondria were prepared with complete recovery from rabbit and porcine heart muscle by upward-flotation during 60 sec of Percoll density gradient centrifugation. 2. Mitochondrial subpopulations were identified and characterized according to buoyant density, electron-microscopy, marker enzyme activities and respiratory performance. 3. ADP-induced state 3-respiration related to latent citrate synthase activity as a marker for structurally intact mitochondria was not significantly different in both mitochondrial subtypes.
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PMID:Rapid preparation of subsarcolemmal and interfibrillar mitochondrial subpopulations from cardiac muscle. 838 38

In vitro specific transcription by the Rickettsia prowazekii RNA polymerase was investigated. The purified rickettsial RNA polymerase, in striking contrast to that of Escherichia coli, could specifically transcribe two R. prowazekii genes (ATP/ADP translocase and citrate synthase genes) and one E. coli gene (RNA-I) on negative supercoiled plasmids but not the same genes on linear plasmids. Following the specific binding of the rickettsial RNA polymerase to the translocase gene promoter on a linear plasmid, there was no detectable open complex formation. Both the E. coli and the R. prowazekii RNA polymerases worked well when poly(dA-dT).poly(dA-dT) or poly(dI-dC).poly-(dI-dC) was used as template for generalized transcription. However, the rickettsial RNA polymerase, in contrast to the E. coli enzyme, had little activity on poly(dG-dC).poly(dG-dC), a template with a larger number of hydrogen bonds. These data indicate that the rickettsial RNA polymerase is weak, at least relative to E. coli, in the function required for the opening of DNA duplex. It appears that this operation in R. prowazekii is aided by the negative supercoiling and the high 72% AT composition of the rickettsial genome.
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PMID:Characterization of the DNA-melting function of the Rickettsia prowazekii RNA polymerase. 844 Jun 83

To investigate the effect of in vivo heart irradiation on myocardial energy metabolism, we measured myocardial adenosine nucleotide concentrations and mitochondrial oxygen consumption in left ventricular tissue of rats 0-16 months after local heart irradiation (20 Gy). At 24 h and 2 months no difference in myocardial adenosine nucleotide concentration was apparent between irradiated and control hearts. The total myocardial adenosine nucleotide concentrations in irradiated hearts compared to those of nonirradiated controls tended to be lower from 4 months onward. The rate of oxidative energy production (state 3 respiration) in irradiated hearts was significantly reduced compared with that of age-matched controls from 2 months onward. Moreover, as a result of aging, a time-dependent decrease in the rate of oxidative energy production was observed in both irradiated and control hearts (P < 0.001). The respiratory control index (RCI = oxygen consumption in state 3/oxygen consumption in state 4) in irradiated hearts was not different from the RCI measured in age-matched control animals. During the period of study the RCI diminished significantly with age in both groups (P < 0.005). The number of oxygen atoms used per molecule of ADP phosphorylated (P/O ratio) was not influenced by the irradiation. The P/O ratio for the NAD(+)-linked substrates remained unchanged at a value of about 3 during the period studied. At 6 months after irradiation activities of myocardial enzymes such as lactate dehydrogenase, creatine kinase, citrate synthase, and cytochrome c oxidase were reduced. The reduction in myocardial energy production and the changes in energy supplies provide a mechanism to explain impaired contractility after local heart irradiation.
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PMID:Effects of in vivo heart irradiation on myocardial energy metabolism in rats. 847 57

Anaerobic ATP production in skeletal muscle and the accumulated oxygen deficit (O2D) incurred during an exhaustive cycle bout (duration = 173 +/- 24 s; intensity = 112 +/- 3% VO2peak), were determined in 10 male cyclists (mean +/- SD: VO2peak = 69.8 +/- 4.2 ml.kg-1.min-1). Anaerobic ATP production (mmol.kg-1 d.w.) was determined from changes in lactate, phosphocreatine, ATP, and ADP in vastus lateralis. Muscle buffer value and the activities of glycogen phosphorylase (PHOS), phosphofructokinase and citrate synthase (CS) were also determined. The anaerobic ATP production determined from measured muscle metabolites was 202.7 +/- 46.9 mmol.kg-1 d.w. and was correlated (P < or = 0.05) with muscle buffer value (r = 0.81), PHOS (r = 0.69) and the ratio of PHOS to CS activity (r = 0.77). The O2D was 55.2 +/- 10.3 ml O2 Eq.kg-1, but was not correlated (P > 0.05) with anaerobic ATP production (r = -0.38), buffer value (r = -0.50) or PHOS (r = -0.39). These latter findings could be explained by error in measuring the O2D and/or muscle anaerobic ATP production in well-trained cyclists.
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PMID:Anaerobic ATP production and accumulated O2 deficit in cyclists. 877 20

Transcriptional regulation was demonstrated in Rickettsia prowazekii, an obligate intracytoplasmic bacterium. The level of citrate synthase (gltA) mRNA II, from promoter P2, was greater in the total RNA isolated from heavily infected L929 cells than in moderately infected L929 cells; conversely, the level of ATP/ADP translocase (tlc) mRNA was greater in moderately infected cells. The level of gltA mRNA I, from promoter P1, did not change under these conditions. The chemical half-lives of gltA mRNA II and tlc mRNA under these conditions were very similar.
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PMID:Transcriptional regulation in the obligate intracytoplasmic bacterium Rickettsia prowazekii. 880 50

The objective of this study was to investigate the effects of single and repeated administration of CP-55,940 [(-)-cis-3-[2-hydroxy-4-(1, 1-dimethylheptyl)-phenyl]-trans-4-(3-hydroxypropyl)cyclohexanol)] on behaviour, energy metabolism and biotransformation. Single intraperitoneal administration to male Sprague-Dawley rats of CP-55,940 (0.4 mg/kg), induced a behavioural response characterized by 'splayed hind limbs', antinociception, hypothermia and a decrease in locomotor activity. Brain and liver mitochondria of the CP-55,940-treated rats exhibited an increase in respiration and no changes in ADP/O and citrate synthase specific activity. Repeated intraperitoneal administration of CP-55,940 (0.4 mg/kg, 11 days) induced behavioural tolerance, disappearance of the increase in the mitochondrial oxygen consumption as well as an increase in the monooxygenase activities and the content of liver microsomal cytochrome P450. Some hepatic metabolizing enzymes of the cytosolic glutathione-centre system were also affected. Previous studies had indicated that the tolerance after chronic administration of CP-55,940 could be due to down-regulation of brain cannabinoid receptors. The present findings demonstrate that the behavioural tolerance occurs together with modified biotransformation activities.
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PMID:Chronic cannabinoid, CP-55,940, administration alters biotransformation in the rat. 890 24

1. To examine metabolic correlates of insulin resistance in skeletal muscle, we used 31P magnetic resonance spectroscopy to study glycogenolytic and oxidative ATP synthesis in leg muscle of lean and obese Zucker rats in vivo during 6 min sciatic nerve stimulation at 2 Hz. 2. The water content of resting muscle was reduced by 21 +/- 7% in obese (insulin-resistant) animals compared with lean animals, whereas the lipid content was increased by 140 +/- 70%. These results suggest that intracellular water content was reduced by 17% in obese animals. 3. During exercise, although twitch tensions were not significantly different in the two groups, rates of total ATP synthesis (expressed per litre of intracellular water) were 48 +/- 20% higher in obese animals, suggesting a 50 +/- 8% reduction in intrinsic "metabolic efficiency'. Changes in phosphocreatine and ADP concentration were significantly greater in obese animals than in lean animals, whereas changes in intracellular pH did not differ. 4. These results imply that oxidative ATP synthesis during exercise is activated earlier in obese animals than in lean animals. This difference was not fully accounted for by the greater increase in the concentration of the mitochondrial activating signal ADP. Neither the post-exercise recovery kinetics of phosphocreatine nor the muscle content of the mitochondrial marker enzyme citrate synthase was significantly different in the two groups. The increased oxidative ATP synthesis in exercise must therefore be due to altered kinetics of mitochondrial activation by signals other than ADP. 5. Thus, the insulin-resistant muscle of obese animals may compensate for its decreased efficiency (and consequent increased need for ATP) by increased reliance on oxidative ATP synthesis.
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PMID:Increased oxidative and delayed glycogenolytic ATP synthesis in exercising skeletal muscle of obese (insulin-resistant) Zucker rats. 897 4


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