Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.4.1.1 (pyruvate carboxylase)
 1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of "satellite" enzymes related to gluconeogenesis has been measured in the oocytes and embryos at the early stages of loach (Misgurnus fossilis L.) embryogenesis. The activity of pyruvate dehydrogenase increase during oocyte maturation by 30%, remains constant at the cleavage and blastula stages and decreased on the onset of gastrulation. In the both oocytes and embryos pyruvate dehydrogenase has been found only in the active form. The activity of citrate synthase, malate dehydrogenase and pyruvate carboxylase remained constant during oocyte maturation and et all early stage of embrional development. Citrate lyase and "malic"-enzyme were not found, Oocyte maturation is followed by a considerable increase in the malate and oxalacetate content, the level of pyruvate and acetyl-CoA being found invariable.
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PMID:[Characteristics of the activity of "satellite" enzymes of gluconeogenesis in the oocytes and embryos of loach]. 103 Jun 40

Rat lung mitochondrial preparations were incubated in the preasence of pyruvate and malate. The principal metabolic products measured were citrate and CO2. Citrate formation from pyruvate was found to be dependent on the presence of malate. Significant citrate was formed in the presence of isocitrate and the rate of citrate formation was increased by the addition of pyruvate. Small amounts of citrate were formed by lung mitochondrial preparations in the presence of 2-oxoglutarate and succinate only after the addition of pyruvate. The level of acetyl-CoA was significantly greater in the presence of pyruvate than in the presence of pyruvate plus malate. The addition of malate to lung mitoochondrial preparations increased 14CO2 production from [2-14C] pyruvate into malate and citrate. A low level of pyruvate-dependent H14CO3-incorporation into acid-stable products was observed, principally citrate and malate, but this rate did not exceed 5% of the rate of net citrate formation in the presence of malate and pyruvate. The capacity of rate lung mitochondria to form oxaloacetate from pyruvate alone in vitro is very limited, and would appear to cast doubt on a major role of pyruvate carboxylase in citrate formation. It is concluded that the rate of citrate formation from pyruvate is limited by the availability of intramitochondrial oxaloacetate and the rate of citrate efflux across the mitochondrial membrane.
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PMID:Citrate formation by rat lung mitochondrial preparations. 111 91

1. The activities of gluconeogenic and glycolytic enzymes and the concentrations of citrate, ammonia, amino acids, glycogen, glucose 6-phosphate, acetyl-CoA, lactate and pyruvate were measured in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats. 2. In kidney cortex of diabetic, cortisone-treated and growth hormone-treated rats the activities of glucose 6-phosphatase (EC 3.1.3.9), fructose 1,6-diphosphatase (EC 3.1.3.11) and phosphopyruvate carboxylase (EC 4.1.1.32) were increased. 3. The activities of glutamate dehydrogenase (EC 1.4.1.3), alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.10) and pyruvate carboxylase (EC 6.4.1.1) were increased in diabetic and cortisone-treated rats. In growth hormone-treated rats the activity of aspartate aminotransferase was depressed but those of the other three enzymes were unchanged. 4. The activity of hexokinase (EC 2.7.1.1) was not altered in any of these conditions. Phosphofructokinase (EC 2.7.1.11) activity was depressed only in growth hormone-treated rats. Pyruvate kinase (EC 2.7.1.40) activity was depressed in cortisone-treated and growth hormone-treated rats but unchanged in diabetic rats. 5. Amino acids, acetyl-CoA and glucose 6-phosphate contents were increased in rat kidneys in all these three conditions. Ammonia content was increased in diabetic and cortisone-treated rats but was markedly diminished in growth hormone-treated rats. 6. The [lactate]/[pyruvate] ratio was elevated in diabetic and cortisone-treated rats but unchanged in growth hormone-treated rats. Citrate content was increased in the kidney cortex of diabetic and growth hormone-treated rats but was unchanged in cortisone-treated rats. The activity of ATP citrate lyase (EC 4.1.3.8) was depressed in diabetic and growth hormone-treated rats but was increased in cortisone-treated rats. 7. Glycogen content was moderately elevated in growth hormone-treated rats and markedly elevated in diabetic rats, whereas no change in glycogen content was observed in cortisone-treated rats. Glycogen synthetase (EC 2.4.1.11) activity was unchanged in all these three conditions. Phosphorylase (EC 2.4.1.1) activity was not affected in cortisone-treated rats but was depressed in diabetic and growth hormone-treated rats.
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PMID:Evaluation of the rate-limiting steps in the pathway of glucose metabolism in kidney cortex of normal, diabetic, cortisone-treated and growth hormone-treated rats. 434 56

1. The fixation of CO(2) by pyruvate carboxylase in isolated rat brain mitochondria was investigated. 2. In the presence of pyruvate, ATP, inorganic phosphate and magnesium, rat brain mitochondria fixed H(14)CO(3) (-) into tricarboxylic acid-cycle intermediates at a rate of about 250nmol/30min per mg of protein. 3. Citrate and malate were the main radioactive products with citrate containing most of the radioactivity fixed. The observed rates of H(14)CO(3) (-) fixation and citrate formation correlated with the measured activities of pyruvate carboxylase and citrate synthase in the mitochondria. 4. The carboxylation of pyruvate by the mitochondria had an apparent K(m) for pyruvate of about 0.5mm. 5. Pyruvate carboxylation was inhibited by ADP and dinitrophenol. 6. Malate, succinate, fumarate and oxaloacetate inhibited the carboxylation of pyruvate whereas glutamate stimulated it. 7. The results suggest that the metabolism of pyruvate via pyruvate carboxylase in brain mitochondria is regulated, in part, by the intramitochondrial concentrations of pyruvate, oxaloacetate and the ATP:ADP ratio.
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PMID:Regulation of pyruvate metabolism via pyruvate carboxylase in rat brain mitochondria. 472 35

1. The effect of oleate on the subcellular distribution of ATP, 2-oxoglutarate, glutamate, citrate, malate and phosphoenolpyruvate was studied in hepatocytes from rats starved for 48 h by applying a modified digitonin method. The results markedly differ from those observed after glucagon [Siess, E. A., Brocks, D. G., Lattke, H. K., and Wieland, O. H. (1977) Biochem J. 166, 225-235]. Total cellular amounts and the distribution of ATP and 2-oxoglutarate remained unchanged. In the mitochondrial matrix glutamate was increased, while mitochondrial phospho-enolpyruvate was decreased. Citrate and malate were increased both in the mitochondrial and cytosolic space. 2. In contrast to the effect of glucagon, gluconeogenesis from dihydroxyacetone, fructose or glutamine was not stimulated by oleate. Gluconeogenesis from propionate was even inhibited by the fatty acid. 3. The stimulation by glucagon of glucose production from dihydroxyacetone or fructose was undiminished in biotin-deficient hepatocytes. Glucose formation from lactate, however, was stimulated only in biotin-substituted hepatocytes. 4. The results indicate that oleate stimulates gluconeogenesis by increasing pyruvate carboxylase activity (EC 6.4.1.1), whereas glucagon displays a more complex mode of action.
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PMID:Distinctive roles of oleate and glucagen in gluconeogenesis. 746 Sep 51

Enterocytes from fasted rabbits make glucose from exogenous fructose and dihydroxyacetone at rates of 180 and 91 nmol/min/10(8) cells but do not make glucose from glycerol, aspartate, malate, lactate, alpha-ketoglutarate, glutamate or glutamine. Total activities of phosphoenolpyruvate carboxykinase, fructose 1,6-bisphosphatase and glucose 6-phosphatase in isolated enterocytes are 0.44, 0.60 and 1.90 mumol/min/10(8) cells, and > or = 95% of carboxykinase activity is intramitochondrial. Enterocytes contain marginal glycerol kinase (0.05 mumol/ min/10(8) cells) and essentially no pyruvate carboxylase activities. Enterocyte mitochondria synthesize citrate from exogenous phosphoenolpyruvate and acetylcarnitine at a rate of 2.40 nmol/min/mg protein. Citrate formation is highly dependent on exogenous HCO3 and inhibited strongly by 3-mercaptopicolinate and 1,2,3-benzenetricarboxylate. Citrate synthesis is stimulated consistently by GDP and significantly so by GTP. Citrate production is unaffected by ADP or ATP. Enterocytes from fasted-refed rabbits contain activities of 0.05, 0.12, 0.39 and 0.56 mumol/min/mg cytosolic protein of ATP:citrate lyase, NADP:malate dehydrogenase, glucose 6-phosphate dehydrogenase and NADP:isocitrate dehydrogenase. Activities of NADP:malate dehydrogenase, glucose 6-phosphate dehydrogenase and NADP:isocitrate dehydrogenase are significantly higher in enterocytes from fasted-refed rabbits than those from fasted rabbits. Mitochondrial phosphoenolpyruvate carboxykinase in enterocytes in vivo could convert glycolysis-derived phosphoenolpyruvate to oxaloacetate that, with acetyl CoA, could form citrate for export to support cytosolic lipogenesis as an activator of acetyl CoA carboxylase, a source of carbon via ATP:citrate lyase and of NADPH via NADP:malate dehydrogenase or NADP:isocitrate dehydrogenase.
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PMID:Synthesis of citrate from phosphoenolpyruvate and acetylcarnitine by mitochondria from rabbit enterocytes: implications for lipogenesis. 946 72

Citric acid secretion by fluorescent pseudomonads has a distinct significance in microbial phosphate solubilization. The role of citrate synthase in citric acid biosynthesis and glucose catabolism in pseudomonads was investigated by overexpressing the Escherichia coli citrate synthase (gltA) gene in Pseudomonas fluorescens ATCC 13525. The resultant approximately 2-fold increase in citrate synthase activity in the gltA-overexpressing strain Pf(pAB7) enhanced the intracellular and extracellular citric acid yields during the stationary phase, by about 2- and 26-fold, respectively, as compared to the control, without affecting the growth rate, glucose depletion rate or biomass yield. Decreased glucose consumption was paralleled by increased gluconic acid production due to an increase in glucose dehydrogenase activity. While the extracellular acetic acid yield increased in Pf(pAB7), pyruvic acid secretion decreased, correlating with an increase in pyruvate carboxylase activity and suggesting an increased demand for the anabolic precursor oxaloacetate. Activities of two other key enzymes, glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase, remained unaltered, and the contribution of phosphoenolpyruvate carboxylase and isocitrate lyase to glucose catabolism was negligible. Strain Pf(pAB7) demonstrated an enhanced phosphate-solubilizing ability compared to the control. Co-expression of the Synechococcus elongatus PCC 6301 phosphoenolpyruvate carboxylase and E. coli gltA genes in P. fluorescens ATCC 13525, so as to supplement oxaloacetate for citrate biosynthesis, neither significantly affected citrate biosynthesis nor caused any change in the other physiological and biochemical parameters measured, despite approximately 1.3- and 5-fold increases in citrate synthase and phosphoenolpyruvate carboxylase activities, respectively. Thus, our results demonstrate that citrate synthase is rate-limiting in enhancing citrate biosynthesis in P. fluorescens ATCC 13525. Significantly low extracellular citrate levels as compared to the intracellular levels in Pf(pAB7) suggested a probable limitation of efficient citrate transport.
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PMID:Enhanced citric acid biosynthesis in Pseudomonas fluorescens ATCC 13525 by overexpression of the Escherichia coli citrate synthase gene. 1944 43

Carbon dioxide has been known for some time to be one of the products of carbohydrate metabolism. More recently it has been demonstrated that CO2 is utilized in pathways of carbohydrate synthesis. Five reactions have been described by which CO2 is incorporated into citric acid intermediates. Two important functions of CO2 fixation reactions have been suggested. Citric acid cycle intermediates can be generated by the fixation reactions and schemes utilizing two of the reaction will reverse the pyruvic kinase reaction. The latter is a step essential to glucogenesis. This paper shows that carbon dioxide fixation occurs in rat skin. The labeling pattern of oxaloacetate after fixation is consistent with patterns predicted by either the malic enzyme or propionyl carboxylase fixation reactions. The presence of the phosphopyruvic carboxykinase and pyruvic carboxylase reactions cannot be definitely ruled out by the experimental data. More work on the enzymatic level should show the significance of these various fixaon reactions in skin. Further experiments may also elucidate a relationship between factors known to affect the fixation reactions which also produce gross and microscopic changes in skin.
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PMID:Carbon dioxide fixation in skin. 2562 43