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)

To evaluate the participation of proteins derived from mitochondrial genes in the adaptive response of skeletal muscle to increased contractile activity, we administered chloramphenicol (CAP; 200-1,000 mg.kg-1.day-1), an inhibitor of translation from mitochondrial ribosomes, to adult rabbits undergoing electrical stimulation of the tibialis anterior muscle of one hind limb. In unmedicated animals, 10 days of electrical stimulation increased maximum velocity (Vmax) of cytochrome oxidase and citrate synthase by 214 +/- 17 and 201 +/- 16% (P less than 0.01). In a dose-dependent manner, CAP abolished activity-induced increases in cytochrome oxidase Vmax, suggesting that augmented mitochondrial protein synthesis is necessary for the adaptive response of enzymes that require protein subunits encoded by mitochondrial genes. However, CAP failed to inhibit activity-induced changes in Vmax of enzymes derived exclusively from nuclear genes (citrate synthase and aldolase). CAP also failed to inhibit activity-induced increases in mRNA transcribed from the nuclear genes encoding beta-F1 ATPase or myoglobin, or from the mitochondrial genes encoding 12S rRNA, 16S rRNA, or cytochrome b. These latter findings suggest that mitochondrial translation products do not participate in pretranslational regulation of these nuclear or mitochondrial genes in response to changes in contractile activity of skeletal muscle.
Am J Physiol 1987 Dec
PMID:Effects of inhibition of mitochondrial protein synthesis in skeletal muscle. 289 13

The effects of silicon deficiency on the activities of several enzymes involved in lipid and storage carbohydrate synthesis in the diatom Cyclotella cryptica were determined. The activity of UDPglucose pyrophosphorylase was not affected after 4 h of silicon-deficient growth, but the activity of UDPglucose: beta-(1----3)-glucan-beta-3-glucosyltransferase (chrysolaminarin synthase) was reduced by 31% during this period. Acetyl-CoA synthetase, acetyl-CoA hydrolase, and citrate synthase activities were present in cell-free extracts of C. cryptica, but did not change in response to 4 h of silicon deficiency. However, the activity of acetyl-CoA carboxylase increased approximately two- and fourfold after 4 and 15 h of silicon-deficient growth, respectively. This induction could be blocked by cycloheximide (20 micrograms/ml) and actinomycin D (10 micrograms/ml), suggesting that silicon deficiency may induce an increase in the rate of acetyl-CoA carboxylase synthesis. These changes in enzymatic activity may be partially responsible for the accumulation of lipids that has been observed in C. cryptica and other diatoms in response to silicon deficiency.
Arch Biochem Biophys 1988 Dec
PMID:Changes in the activities of various lipid and carbohydrate biosynthetic enzymes in the diatom Cyclotella cryptica in response to silicon deficiency. 290 94

The structural gene for citrate synthase of Acinetobacter anitratum has been cloned in Escherichia coli in a form which expresses the enzyme. A library of EcoRI fragments of Acinetobacter genomic DNA was prepared in the vector lambda gt10, and clones were screened by hybridization with an E. coli citrate synthase clone under conditions of reduced stringency. A 6.5 kbp clone was obtained which was subcloned into pBR322, and shown to direct the formation of Acinetobacter citrate synthase in E. coli hosts. The promoter was located within a BglII fragment, and from this information the orientation of the gene was deduced.
Biochem Biophys Res Commun 1986 Dec 15
PMID:Molecular cloning of the structural gene for Acinetobacter citrate synthase. 302 91

A cDNA that encodes pig citrate synthase (PCS) was inserted into a plasmid T7 vector and was expressed in an E. coli gltA mutant. Up to 10 mg of purified PCS was obtained from 2 liters of E. coli. The mammalian protein produced in E. coli comigrated with the enzyme purified from pig heart on a SDS-polyacrylamide gel (SDS-PAGE) with an Mr of 50,000, and reacted with a polyclonal antibody directed against pig heart citrate synthase. The Vmax and Km of the expressed PCS were indistinguishable from those of the pig heart enzyme. The PCS produced in E. coli did not contain the trimethylation modification of Lys 368, characteristic of the pig heart enzyme. These data suggest that the PCS protein produced in E. coli is catalytically similar to the enzyme purified from pig heart and methylation of Lys 368 is not essential for catalysis.
Biochem Biophys Res Commun 1988 Dec 30
PMID:Characterization of mutant TMK368K pig citrate synthase expressed in and isolated from Escherichia coli. 314 69

The activity of branched-chain aminotransferase in mitochondria isolated from rat tissues was examined, and the mitochondrial contribution to total tissue branched-chain aminotransferase activity was calculated using the mitochondrial marker enzyme citrate synthase. Mitochondrial aminotransferase activity was highest in heart followed by skeletal muscle, kidney and brain. In heart muscle all of the aminotransferase activity was accounted for by the mitochondrial fraction. Activity was found to be mitochondrial in skeletal muscle with high red fiber content and also in kidney cortex. Activity was predominantly cytosolic in brain and muscles with high white fiber composition. Thus, the distribution of branched-chain aminotransferase activity in skeletal muscle was dependent on fiber type. No branched-chain aminotransferase activity was detected in liver mitochondria, and in liver tissue activity was too low to be relevant at physiological concentrations of branched-chain amino acids. Within a tissue, regardless of the subcellular distribution of aminotransferase activity, the relative rates of transamination with subsaturating or "saturating" concentrations of KIV or isoleucine were similar. Finally, amino acid preference was also similar within a tissue, but not necessarily between or among different tissues.
J Nutr 1988 Dec
PMID:Subcellular distribution of branched-chain aminotransferase activity in rat tissues. 321 76

A transcript analysis of the citrate synthase and succinate dehydrogenase genes (gltA-sdhCDAB) of Escherichia coli was done by nuclease S1 mapping. Evidence was obtained for two monocistronic gltA transcripts extending anti-clockwise, to a common terminus, from independent promoters with start points 196 bp (major) and 299 bp (minor) upstream of the gltA coding region. Evidence was also obtained for two polycistronic sdh transcripts, sdhCDAB (minor) and sdhDAB (major), extending clockwise, from sites 219 bp upstream of sdhC and 1455 bp upstream of sdhD (i.e. within sdhC), to a common terminus. The synthesis of all of the transcripts was repressed by growth in the presence of glucose, and this is consistent with the well-established fact that both enzymes are subject to catabolite repression. Sequences resembling known binding sites for the cAMP-CRP (cyclic AMP-cyclicAMP receptor protein) complex occur in the vicinity of each promoter suggesting that they are activated by the cAMP-CRP complex.
J Gen Microbiol 1986 Dec
PMID:Transcript analysis of the citrate synthase and succinate dehydrogenase genes of Escherichia coli K12. 330 32

Mechanical responses of isolated atria to (-)-isoproterenol and activities of myocardial pyruvate kinase and citrate synthase, enzymes involved in energy metabolism, were assessed in rats 7 days after 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment. Basal tension development by electrically paced left atria was significantly elevated by all doses of TCDD (6.25, 25, or 100 micrograms/kg) when compared to that of vehicle-treated rats with unlimited access to feed. The basal rate of spontaneously beating right atria was significantly depressed in rats receiving 100 micrograms/kg TCDD. In left atria from rats treated with 100 micrograms/kg TCDD, maximal inotropic responses to (-)-isoproterenol and 1-methyl-3-isobutylxanthine were enhanced to the same degree. Right and left atria from rats receiving 100 micrograms/kg TCDD had an increased sensitivity to the chronotropic and inotropic effects of (-)-isoproterenol, respectively. The augmented atrial effects caused by TCDD were not secondary to loss of body weight because pair-fed animals that lost the same amount of weight did not display the responses. The ratio of heart ventricular mass to body weight and the activities of pyruvate kinase and citrate synthase in homogenates of heart ventricular muscle were not affected by TCDD treatment. Thus, overtly toxic doses of TCDD in the rat did not depress mechanical function of the heart.
Toxicol Appl Pharmacol 1987 Dec
PMID:Effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment on mechanical function of the rat heart. 342 79

An isolated single rat hindlimb muscle preparation was used to examine the influence of exercise training on leucine metabolism during steady-state conditions at rest and during isometric contractions. Treadmill training increased the activity of citrate synthase in the hindlimb muscle by 40-45%. Leucine oxidation, measured as the rate of alpha-decarboxylation, was not different between trained (2.28 +/- 0.15 nmol.min-1.g-1, n = 9) and control (2.57 +/- 0.20, n = 9) muscle at rest. In addition, successive 40-min contraction periods at 15 and 45 tetani/min induced similar increases (50 and 100%, respectively) in leucine oxidation in both groups. However, trained muscle maintained a greater tension output (P less than 0.05) during contractions and exhibited a greater oxygen consumption (VO2) (P less than 0.05) during 45 tetani/min. Thus the rate of leucine oxidation, relative to VO2, was less (P less than 0.05) in the trained group. This response was probably related to differences in intracellular factors modulating branched-chain alpha-keto acid dehydrogenase, the rate-limiting step in leucine oxidation. Although our observed rates of muscle leucine alpha-decarboxylation can reasonably account for the rates of whole-body leucine alpha-decarboxylation of nontrained individuals found during steady-state tracer studies in vivo, this is less reasonably the case for the trained group. This suggests that a greater rate of leucine oxidation by nonmuscle tissues (e.g., liver) may occur in trained compared with nontrained individuals.
Am J Physiol 1987 Dec
PMID:Effect of endurance training on leucine metabolism in perfused rat skeletal muscle. 342 11

In an effort to describe the skeletal muscle characteristics of trained triathletes, biopsies were obtained from the gastrocnemius, vastus lateralis, and posterior deltoid muscles of 11 triathletes and 4 normally active controls. Each specimen was analyzed for muscle fiber composition, respiratory capacity (QO2), and citrate synthase activity. The mean (+/- SE) percentage of type I fibers for the triathletes was 59 (4.0), 63 (3.3), and 60 (2.8) in the gastrocnemius, vastus lateralis, and deltoid, respectively (P greater than 0.05). The mean (+/- SE) QO2 values in the gastrocnemius (4.4 +/- 0.3 ml O2.min-1.g-1) and the vastus lateralis (4.1 +/- 0.2) were not significantly different while the QO2 values of the deltoid (3.6 +/- 0.2) were significantly lower than the gastrocnemius (P less than 0.05). The mean citrate synthase activity of the deltoid (27.7 +/- 1.7 mumol.min-1.g-1) was significantly lower than both the vastus lateralis (36.0 +/- 3.2) and the gastrocnemius (45.8 +/- 2.1) (P less than 0.05). There was a high correlation between the percentage of type I fibers and the citrate synthase activity within the vastus lateralis (r = .760) and deltoid (r = .610) (P less than 0.05) but not the gastrocnemius (r = .200). No significant relationships were observed between skeletal muscle characteristics and VO2 max nor between skeletal muscle characteristics and performance. The results of this study demonstrate that: (1) these triathletes have a high percentage of type I fibers in all three muscle groups; (2) skeletal muscle characteristics were not highly related to laboratory or competitive performance;(ABSTRACT TRUNCATED AT 250 WORDS)
Int J Sports Med 1987 Dec
PMID:Muscle fiber composition and respiratory capacity in triathletes. 342 82

Thirty-six biopsy specimens of human biceps and vastus lateralis muscles were examined by histometric analysis and determination of enzyme activities (phosphorylase, triosephosphate dehydrogenase, 3-hydroxacyl-CoA-dehydrogenase, lactate dehydrogenase, hexose isomerase, citrate synthetase, 6-phosphogluconate dehydrogenase). The series included 13 specimens from patients suffering from a benign form of muscular dystrophy (limb girdle and Becker type of muscular dystrophy) and 12 specimens from patients with an acute (n = 5) or chronic (n = 7) form of myositis. Muscle fibres were atrophic in myositis and hypertrophic (with an increased variation of fibre diameters) in muscular dystrophies, as has been shown previously. When myositis samples were compared with either normal or dystrophic muscles, a highly significant lowering of glycolytic enzyme activity was found in chronic myositis, while the activity of 6-phosphogluconate dehydrogenase was elevated to highly significant levels. Measurements of the latter enzyme's activity might be of additional value in differentiating chronic forms of myositis from benign muscular dystrophies.
J Neurol 1987 Dec
PMID:Additional biochemical criteria in the differential diagnosis of myositis. 343 Jan 87


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