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)

Thermogenic capabilities of red-winged blackbirds improve markedly during their 10-12-day nestling period, especially between day 5 and day 8. The time course of improvements may be determined by the maturation of skeletal muscles involved in shivering thermogenesis, particularly the pectoralis muscles. To test this hypothesis, morphological and biochemical changes in pectoral and leg muscles were measured in young and adult blackbirds. Both muscles grew disproportionately relative to body mass. The pectoralis consisted entirely of fast-twitch fibers, predominantly fast oxidative glycolytic. In contrast, the gastrocnemius muscle consisted of a mixture of slow and fast fibers (predominantly fast glycolytic). Although fiber composition was constant, both cross-sectional area and density of fibers increased with age in both muscles. Catabolic capacities of the pectoralis increased significantly (approximately 7-8-fold) throughout the nestling period, most abruptly after day 3 (citrate synthase, CS) or day 4 (3-hydroxacyl-CoA-dehydrogenase, HOAD). Myofibrillar ATPase activities in the pectoralis were initially low, but increased after day 5. Further increases in CS and myofibrillar ATPase activities occurred in the pectoralis after fledging. CS and HOAD activities in the leg were much lower, but myofibrillar ATPase activities were remarkably similar in the two muscles, differing only in adults. These results are consistent with the hypothesis that the development of endothermy is dependent on the morphological and biochemical maturation of skeletal muscles important in thermogenesis.
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PMID:Ontogeny of catabolic and morphological properties of skeletal muscle of the red-winged blackbird (Agelaius phoeniceus). 1168 11

As in many other fleshy fruits, the predominant organic acids in ripe peach (Prunus persica (L.) Batsch) fruit are malic and citric acids. The accumulation of these metabolites in fruit flesh is regulated during fruit development. Six peach fruit-related genes implicated in organic acid metabolism (mitochondrial citrate synthase; cytosolic NAD-dependent malate dehydrogenase, and cytosolic NADP-dependent isocitrate dehydrogenase) and storage (vacuolar proton translocating pumps: one vacuolar H+-ATPase, and two vacuolar H+-pyrophosphatases) were cloned. Five of these peach genes were homologous to genes isolated from fruit in other fleshy fruit species. Phylogenetic and expression analyses suggested the existence of a particular vacuolar pyrophosphatase highly expressed in fruit. The sixth gene was the first cytosolic NAD-dependent malate dehydrogenase gene isolated from fruit. Gene expression was studied during the fruit development of two peach cultivars, a normal-acid (Fantasia) and a low-acid (Jalousia) cultivar. The overall expression patterns of the organic acid-related genes appeared strikingly similar for the two cultivars. The genes involved in organic acid metabolism showed a stronger expression in ripening fruit than during the earlier phases of development, but their expression patterns were not necessarily correlated with the changes in organic acid contents. The tonoplast proton pumps showed a biphasic expression pattern more consistent with the patterns of organic acid accumulation, and the tonoplast pyrophosphatases were more highly expressed in the fruit of the low-acid cultivar during the second rapid growth phase of the fruit.
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PMID:Isolation and characterization of six peach cDNAs encoding key proteins in organic acid metabolism and solute accumulation: involvement in regulating peach fruit acidity. 1190 73

A mechanism decreasing oxidative metabolism during normal cell division and growth is expected to direct substrates toward biosyntheses rather than toward complete oxidation to CO(2). Hence, any event decreasing oxidative phosphorylations (OXPHOS) could provide a proliferating advantage to a transformed or tumor cell in an oxidative tissue. To test this hypothesis, we studied mitochondrial enzymes, DNA and OXPHOS protein content in three types of renal tumors from 25 patients. Renal cell carcinomas (RCCs) of clear cell type (CCRCCs) originate from the proximal tubule and are most aggressive. Chromophilic RCCs, from similar proximal origin, are less aggressive. The benign renal oncocytomas originate from collecting duct cells. Mitochondrial enzyme and DNA contents in all tumor types or grades differed significantly from normal tissue. Mitochondrial impairment increased from the less aggressive to the most aggressive RCCs, and correlated with a considerably decreased content of OXPHOS complexes (complexes II, III, and IV of the respiratory chain, and ATPase/ATP synthase) rather than to the mitochondrial content (citrate synthase and mitochondrial (mt)DNA). In benign oncocytoma, some mitochondrial parameters (mtDNA, citrate synthase, and complex IV) were increased 4- to 7-fold, and some were slightly increased by a factor of 2 (complex V) or close to normal (complexes II and III). A low content of complex V protein was found in all CCRCC and chromophilic tumors studied. However F(1)-ATPase activity was not consistently decreased and its impairment was associated with increased aggressiveness in CCRCCs. Immunodetection of free F(1)-sector of complex V demonstrated a disturbed assembly/stability of complex V in several CCRCC and chromophilic tumors. All results are in agreement with the hypothesis that a decreased OXPHOS capacity favors faster growth or increased invasiveness.
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PMID:Low mitochondrial respiratory chain content correlates with tumor aggressiveness in renal cell carcinoma. 1201 48

The use of tamoxifen (TAM) has been questioned on the chemotherapy and chemoprevention of breast cancer due to several estrogen receptor-independent cytotoxic effects. As an alternative, its more active metabolite 4-hydroxytamoxifen (OHTAM) has been proposed with presumed lower side effects. In this work, the potential OHTAM toxicity on rat liver mitochondrial bioenergetics in relation to the multiple deleterious effects of TAM was evaluated. OHTAM, at concentrations lower than those putatively reached in tissues following the administration of TAM, does not induce significant perturbations on the respiratory control ratio (RCR), ADP/O, transmembrane potential (DeltaPsi), phosphorylative capacity and membrane integrity of mitochondria. However, at high concentrations, OHTAM depresses the DeltaPsi, RCR and ADP/O, affecting the phosphorylation efficiency, as also inferred from the DeltaPsi fluctuations and pH changes associated with ADP phosphorylation. Moreover, OHTAM, at concentrations that stimulate the rate of state 4 respiration in parallel to the decrease in the DeltaPsi and phosphorylation rate, causes mitochondrial swelling and stimulates both ATPase and citrate synthase activities. However, the OHTAM-observed effects, at high concentrations, are not significant relatively to the damaging effects promoted by TAM and suggest alterations to mitochondrial functions due to proton leak across the mitochondrial inner membrane.
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PMID:4-Hydroxytamoxifen induces slight uncoupling of mitochondrial oxidative phosphorylation system in relation to the deleterious effects of tamoxifen. 1227 May 94

We have cloned, purified to homogeneity, and characterized as a molecular chaperone the Escherichia coli YedU protein. The purified protein shows a single band at 31 kDa on SDS-polyacrylamide gels and forms dimers in solution. Like other chaperones, YedU interacts with unfolded and denatured proteins. It promotes the functional folding of citrate synthase and alpha-glucosidase after urea denaturation and prevents the aggregation of citrate synthase under heat shock conditions. YedU forms complexes with the permanently unfolded protein, reduced carboxymethyl alpha-lactalbumin. In contrast to DnaK/Hsp70, ATP does not stimulate YedU-dependent citrate synthase renaturation and does not affect the interaction between YedU and unfolded proteins, and YedU does not display any peptide-stimulated ATPase activity. We conclude that YedU is a novel chaperone which functions independently of an ATP/ADP cycle.
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PMID:Characterization of the Escherichia coli YedU protein as a molecular chaperone. 1256 79

We report the characterization of the first chaperonin (Mm-cpn) from a mesophilic archaeon, Methanococcus maripaludis. The single gene was cloned from genomic DNA and expressed in Escherichia coli to produce a recombinant protein of 543 amino acids. In contrast with other known archaeal chaperonins, Mm-cpn is fully functional in all respects under physiological conditions of 37 degrees C. The complex has Mg(2+)-dependent ATPase activity and can prevent the aggregation of citrate synthase. It promotes a high-yield refolding of guanidinium-chloride-denatured rhodanese in a nucleotide-dependent manner. ATP binding is sufficient to effect folding, but ATP hydrolysis is not essential.
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PMID:Nucleotide-dependent protein folding in the type II chaperonin from the mesophilic archaeon Methanococcus maripaludis. 1262

The present study was conducted to investigate the effects of long-term exercise training on the main components involved in excitation-contraction coupling and relaxation in rat myocardium. Twenty male Wistar rats were divided into sedentary (S) and treadmill-trained (T) groups. Group T was trained for 24 weeks, 5 days/week (25 m/min, 45-60 min, 0% slope). 48 h after the last exercise session, animals were killed and ventricular and soleus muscle homogenates were obtained. The citrate synthase activity in soleus muscle was significantly increased (163%) in T compared with S rats ( P<0.01), confirming the exercise training efficacy. Although heart weight and cardiac oxidative capacity were not modified by exercise training, the binding of [(3)H] ryanodine and the dihydropyridine [(3)H]PN200-110 to cardiac homogenates, and sarcoplasmic reticulum Ca(2+)-ATPase activity were increased significantly in the ventricular homogenates from T compared with S animals ( P<0.01). Western blot analysis of ventricular homogenates failed to show significant alterations in dihydropyridine receptor and Ca(2+)-ATPase levels in T animals, but revealed an increase of ryanodine receptor density in this group ( P<0.01). The activity of the ectoenzymes 5'-nucleotidase and Mg(2+)-ATPase was not affected by training ( P>0.05). In conclusion, long-term treadmill training induces adaptive changes in some of the components of myocardial rat excitation-contraction coupling and relaxation systems that could contribute to the improvement of cardiac function.
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PMID:Ca2+ regulatory systems in rat myocardium are altered by 24 weeks treadmill training. 1273 53

We examined the mechanistic basis for two whole-animal performance traits, aerobic capacity and burst speed, in six laboratory-reared Trinidadian guppy populations from different native drainages with contrasting levels of predation. Using within- and between-population variation, we tested whether variation in organs and organ systems (heart, gill and swimming motor mass) and the activities of several enzymes that support locomotion (citrate synthetase, lactate dehydrogenase and myofibrillar ATPase) are correlated with aerobic performance (maximum rates of oxygen consumption, (O(2)max)) or burst performance (maximum swim speed during escape responses). We also tested for associations between physiological traits and habitat type (different drainages and predation levels). Organ size and enzyme activities showed substantial size-independent variation, and both performance measures were strongly correlated to body size. After accounting for size effects, neither burst nor aerobic performance was strongly correlated to any organ size or enzymatic variable, or to each other. Two principal components (PCI, PC2) in both males and females accounted for most of the variance in the organ size and enzymatic variables. In both sexes, heart and gill mass tended to covary and were negatively associated with citrate synthetase and lactate dehydrogenase activity. In males (but not females), variation in aerobic performance was weakly but significantly correlated to variation in PC1, suggesting that heart and gill mass scale positively with (O(2)max). Neither of the component variables and no single morphological or enzymatic trait was correlated to burst speed in either sex. Evolutionary changes in important life history traits occur rapidly in guppy populations subjected to different predation intensities (high mortality in downstream sites inhabited by large predatory fish; low mortality in upstream sites lacking large predators). We found significant differences between stream drainages in all morphological variables and most enzymatic variables, but only the mass of the swimming motor and LDH activity were significantly affected by predation regime. Overall, our data show that microevolution has occurred in the physiological foundations of locomotor performance in guppies, but evolutionary changes in physiology do not closely correspond to the predation-induced changes in life history parameters.
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PMID:Morphological and enzymatic correlates of aerobic and burst performance in different populations of Trinidadian guppies Poecilia reticulata. 1296 62

The yjoB gene of Bacillus subtilis encodes a 48.8-kDa protein belonging to the AAA family. Members of this family contain a 200-250-amino acid residues AAA domain carrying a Walker A and B ATP-binding site assumed to be part of a molecular chaperone. The yjoB gene belongs to the sigmaW regulon, and members of this regulon have been reported to be transiently induced when cells enter the stationary growth phase. This assumption was confirmed here for yjoB by Western blot experiments and by analysis of a transcriptional fusion. Purified YjoB protein exhibited ATPase activity but was unable to prevent aggregation of denatured citrate synthase. An alignment of YjoB with a subgroup of AAA proteins present in Archaea suggests that YjoB might be involved in the modulation of the activity of one or more proteases.
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PMID:The yjoB gene of Bacillus subtilis encodes a protein that is a novel member of the AAA family. 1475 46

To evaluate the hypothesis that increasing the potential for glycolytic metabolism would benefit the functioning of infarcted myocardium, we investigated whether mild exercise training would increase the activities of oxidative enzymes, expression of carbohydrate-related transport proteins (monocarboxylate transporter MCT1 and glucose transporter GLUT4), and myosin heavy chain (MHC) isoforms. Myocardial infarction (MI) was produced by occluding the proximal left coronary artery in rat hearts for 30 min. After the rats performed 6 wk of run training on a treadmill, the wall of the left ventricle was dissected and divided into the anterior wall (AW; infarcted region) and posterior wall (PW; noninfarcted region). MI impaired citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities in the AW (P < 0.01) but not in the noninfarcted PW. No differences in the expression of MCT1 were found in either tissues of AW and PW after MI, whereas exercise training significantly increased the MCT1 expression in all conditions, except AW in the MI rats. Exercise training resulted in an increased expression of GLUT4 protein in the AW in the sham rats and in the PW in the MI rats. The relative amount of MHC-beta was significantly increased in the AW and PW in MI rats compared with sham rats. However, exercise training resulted in a significant increase of MHC-alpha expression in both AW and PW in both sham and MI rats (P < 0.01). These findings suggest that mild exercise training enhanced the potential for glycolytic metabolism and ATPase activity of the myocardium, even in the MI rats, ensuring a beneficial role in the remodeling of the heart.
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PMID:Expression of MHC-beta and MCT1 in cardiac muscle after exercise training in myocardial-infarcted rats. 1513 8


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