Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.1.1.32 (phosphoenolpyruvate carboxykinase)
 4,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Utilization of propionate by sheep liver mitochondria was stimulated equally by pyruvate or alpha-oxoglutarate, with formation predominantly of malate. Pyruvate increased conversion of propionate carbon into citrate, whereas alpha-oxoglutarate increased formation of phosphoenolpyruvate. The fraction of metabolized propionate converted into phosphoenolpyruvate was about 17% in the presence or absence of alpha-oxoglutarate and about 7% in the presence of pyruvate. Pyruvate consumption was inhibited by 80% by 5mm-propionate. 2. Compared with rat liver, sheep liver was characterized by very high activities of phosphoenolpyruvate carboxykinase and moderately high activities of aconitase in the mitochondria and by low activities of ;malic' enzyme, pyruvate kinase and lactate dehydrogenase in the cytosol. Activities of phosphoenolpyruvate carboxy-kinase were similar in liver cytosol from rats and sheep. Activities of malate dehydrogenase and NADP-linked isocitrate dehydrogenase in sheep liver were about half those in rat liver. 3. The phosphate-dicarboxylate antiport was active in sheep liver mitochondria, but compared with rat liver mitochondria the citrate-malate antiport showed only low activity and mitochondrial aconitase was relatively inaccessible to external citrate. The rate of swelling of mitochondria induced by phosphate in solutions of ammonium malate was inversely related to the concentration of malate. 4. The results are discussed in relation to gluconeogenesis from propionate in sheep liver. It is proposed that propionate is converted into malate by the mitochondria and the malate is converted into phosphoenolpyruvate by enzymes in the cytosol. In this way sufficient NADH would be generated in the cytosol to convert the phosphoenolpyruvate into glucose.
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PMID:Synthesis of phosphoenolpyruvate from propionate in sheep liver. 433 60

Changes in mitochondrial and sarcoplasmic proteins using proteinomics and Western blotting in hearts from copper-deficient rats were explored in this study. Also, key enzymes that are involved in cardiac energy metabolism via glycolysis and fatty acid oxidation and related transcription factors were determined. Rats were fed one of two diets: a copper-adequate diet containing 6 mg Cu/kg diet or a diet with less than 1 mg Cu/kg diet for 5 weeks. Copper deficiency was confirmed by low liver copper levels, decreased hematocrit levels and cardiac hypertrophy. Proteinomic data revealed that of the more than 50 proteins identified from the mitochondrial fraction of heart tissue, six were significantly down-regulated and nine were up-regulated. The proteins that were decreased were beta enolase 3, carbonic anhydrase 2, aldose reductase 1, glutathione peroxidase, muscle creatine kinase and mitochondrial aconitase 2. The proteins that were up-regulated were isocitrate dehydrogenase, dihydrolipoamide dehydrogenase, transferrin, subunit d of ATP synthase, transthyretin, preproapolipoprotein A-1, GRP 75, alpha-B crystalline and heat shock protein alpha. Follow-up Western blots on rate-limiting enzymes in glycolysis (phosphofructose kinase), fatty acid oxidation (medium chain acyl dehydrogenase, peroxisome proliferator-actvator receptor-alpha or PPARalpha) and gluconeogenesis (phosphoenolpyruvate carboxykinase) did not reveal changes in metabolic enzymes. However, a significant increase in peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1alpha protein, as well as the transcript, which increased 2.5-fold, was observed. It would appear that increased mitochondrial biogenesis known to occur in copper deficiency hearts is caused by an increased expression in the master regulator of mitochondrial biogenesis, PGC-1alpha.
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PMID:Mitochondrial and sarcoplasmic protein changes in hearts from copper-deficient rats: up-regulation of PGC-1alpha transcript and protein as a cause for mitochondrial biogenesis in copper deficiency. 1899 53

Leishmania parasites proliferate within nutritionally complex niches in their sandfly vector and mammalian hosts. However, the extent to which these parasites utilize different carbon sources remains poorly defined. In this study, we have followed the incorporation of various (13)C-labeled carbon sources into the intracellular and secreted metabolites of Leishmania mexicana promastigotes using gas chromatography-mass spectrometry and (13)C NMR. [U-(13)C]Glucose was rapidly incorporated into intermediates in glycolysis, the pentose phosphate pathway, and the cytoplasmic carbohydrate reserve material, mannogen. Enzymes involved in the upper glycolytic pathway are sequestered within glycosomes, and the ATP and NAD(+) consumed by these reactions were primarily regenerated by the fermentation of phosphoenolpyruvate to succinate (glycosomal succinate fermentation). The initiating enzyme in this pathway, phosphoenolpyruvate carboxykinase, was exclusively localized to the glycosome. Although some of the glycosomal succinate was secreted, most of the C4 dicarboxylic acids generated during succinate fermentation were further catabolized in the TCA cycle. A high rate of TCA cycle anaplerosis was further suggested by measurement of [U-(13)C]aspartate and [U-(13)C]alanine uptake and catabolism. TCA cycle anaplerosis is apparently needed to sustain glutamate production under standard culture conditions. Specifically, inhibition of mitochondrial aconitase with sodium fluoroacetate resulted in the rapid depletion of intracellular glutamate pools and growth arrest. Addition of high concentrations of exogenous glutamate alleviated this growth arrest. These findings suggest that glycosomal and mitochondrial metabolism in Leishmania promastigotes is tightly coupled and that, in contrast to the situation in some other trypanosomatid parasites, the TCA cycle has crucial anabolic functions.
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PMID:Isotopomer profiling of Leishmania mexicana promastigotes reveals important roles for succinate fermentation and aspartate uptake in tricarboxylic acid cycle (TCA) anaplerosis, glutamate synthesis, and growth. 2163 75