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)

Kinetoplastid organisms possess a unique organelle, the glycosome, which compartmentalizes the Embden-Meyerhof segment of glycolysis and several other metabolic pathways. In Trypanosoma brucei many of the enzyme activities localized to the glycosome are stage regulated. Two-dimensional gel analysis was used to examine the characteristics, expression, and biosynthesis of the major glycosomal proteins. Two-dimensional gel maps of glycosomes from slender bloodforms and late intermediate-stumpy bloodforms (the precursors of procyclic forms) were indistinguishable, while those of procyclic form glycosomes showed extensive differences. Glycosomal phosphoenolpyruvate carboxykinase and malate dehydrogenase were identified to have subunit molecular weights of 60 and 34 kDa, respectively. We detected two hitherto undescribed glycosomal proteins, one of which is found only in bloodforms. All of the major proteins, except glucose phosphate isomerase, were highly basic. Stage regulation of glycosomal enzyme activities correlated with stage regulation of specific protein biosynthesis.
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PMID:Trypanosoma brucei: two-dimensional gel analysis of the major glycosomal proteins during the life cycle. 231 10

Glycosomes and mitochondrial vesicles from cultured promastigotes of Leishmania mexicana mexicana have been separated using isopycnic centrifugation on linear sucrose gradients. Hexokinase (EC 2.7.1.2), glucose phosphate isomerase (EC 5.3.1.9), phosphofructokinase (EC 2.7.1.11), glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12), and phosphoenolpyruvate carboxykinase (EC 4.1.1.49) were recovered largely in association with glycosomes (density; 1.215 g/ml). Phosphoglycerate kinase (EC 2.7.2.3) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) had some small glycosomal activity, but were mostly recovered in the soluble fractions. Malate dehydrogenase (EC 1.1.1.37) showed a broad peak corresponding to that of the mitochondrial marker oligomycin-sensitive ATPase (EC 3.6.1.4) (density; 1.190 g/ml). Glutamate dehydrogenase (EC 1.4.1.3) and alanine aminotransferase (EC 2.6.1.2) both showed small mitochondrial peaks, but most of the activities were recovered elsewhere on the gradient and in the soluble fractions. The subcellular location of enzymes in L.m. mexicana amastigotes was investigated by following the release of soluble enzymes from digitonin-treated amastigotes. This revealed distinct cytosolic, mitochondrial, and glycosomal compartments. The findings give an insight into the organization and control of L.m. mexicana promastigote and amastigote energy metabolism.
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PMID:Leishmania mexicana: subcellular distribution of enzymes in amastigotes and promastigotes. 315 38

Crude extracts of both vegetative cells and glycerol-induced microcysts of Myxococcus xanthus contained the following enzyme activities: phosphofructokinase, phosphoglucoisomerase, fructose-1,6-diphosphatase, fructosediphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphopyruvate carboxylase, citrate synthase, isocitrate dehydrogenase, alpha-ketoglutarate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucomutase, and uridine diphosphate glucose pyrophosphorylase. With the exception of isocitrate dehydrogenase, which was present at a fivefold higher concentration in microcysts, all activities in extracts from both types of cells were essentially equal. Hexokinase and pyruvate kinase could not be detected in extracts from either type of cell. Microcysts metabolized acetate at a lower rate than did vegetative cells. Most of this decrease was reflected in a substantial decrease in ability of microcysts to oxidize acetate to CO(2). In addition, microcysts and vegetative cells showed a different distribution of (14)C-label from incorporated acetate.
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PMID:Comparative intermediary metabolism of vegetative cells and microcysts of Myxococcus xanthus. 430 96

Evidence is presented for the occurrence of glycosomes (organelles resembling peroxisomes) in four major species of Leishmania (viz. L. major, L.m. mexicana, L. b. braziliensis and L. donovani), based on latency as well as differential and isopycnic centrifugation studies. The enzymes involved in glycolysis; (hexokinase, phosphoglucose isomerase, phosphofructokinase, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase, glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase); glycerol metabolism (sn-glycerol-3-phosphate dehydrogenase and glycerol kinase); carbon dioxide fixation (phosphoenolpyruvate carboxykinase and possibly malate dehydrogenase); together with an enzyme involved in the beta-oxidation of fatty acids (3-beta-hydroxybutyryl coenzyme A dehydrogenase); a key enzyme in the synthesis of ether lipids (dihydroxyacetone phosphate acyltransferase) as well as the ADP utilising enzyme adenylate kinase, were all found associated, at least in part, with a subcellular organelle which had a buoyant density in sucrose gradients of 1.21 to 1.24 g cm-3. Little variance in enzyme composition was found between the different species of Leishmania or in comparison with other members of the Trypanosomatidae, supporting the unifying principle that glycosomes are a unique characteristic of this family. The occurrence of important catabolic, anabolic and anaplerotic pathways in the glycosomes of Leishmania renders them prime targets for chemotherapy.
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PMID:The occurrence of glycosomes (microbodies) in the promastigote stage of four major Leishmania species. 644 18

Highly purified glycosomes were isolated from Trypanosoma brucei bloodstream forms and cultured procyclic trypomastigotes. A comparison of the specific activities of glycosomal enzymes revealed that glycosomes from insect stages had decreased levels of hexokinase, phosphoglucose isomerase, phospho-fructokinase, fructose-bisphosphate aldolase, glyceraldehyde-phosphate dehydrogenase and phosphoglycerate kinase, but contained increased levels of adenylate kinase, malate dehydrogenase and phosphoenolpyruvate carboxykinase. Glycosomes from bloodstream forms were almost totally devoid of the latter two activities. Comparison of the two types of glycosomes by sodium dodecylsulphate-polyacrylamide gel electrophoresis revealed that bloodstream form glycosomes contained 3 prominent polypeptides (64, 46 and 40 kDa) which were hardly detectable in insect stage glycosomes, whereas the latter contained 3 insect stage specific bands with molecular weight of 34 000, 61 000 and 77 000 and 4 additional bands with molecular weights between 94 000 and 110 000. Both types of glycosome contained the phospholipids phosphatidylcholine and phosphatidylethanolamine. Insect stage glycosomes contained in addition also phosphatidylinositol and some phosphatidylserine.
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PMID:A comparison of the glycosomes (microbodies) isolated from Trypanosoma brucei bloodstream form and cultured procyclic trypomastigotes. 674 87

Recently, it has been reported that paromomycin sulfate has marked anthelmintic efficacy against tapeworm infections in man. In the present study this drug was used in the treatment of 14 cases of diphyllobothriasis latum and 1 case of taeniasis saginata. Also, the actions of paromomycin sulfate on Diphyllobothrium ditremum and D. erinacei were examined pharmacologically using Magnus apparatus and biochemical methods. The results obtained were as follows. For the treatment, a total of 50 mg/kg of paromomycin sulfate divided into 2 doses was given orally at intervals of 30 minutes. Two hours after medication, 20 g of magnesium sulfate dissolved in 200--300 ml of water was given as purgative. One or 2 worms were found in the stools of 11 cases with D. latum and 1 case with T. saginata within 24 hours after medication, but scolex was found in only 2 of them. All cases were negative for the eggs or segments in stool examinations at 1 and 3 months after treatment. Except 1 case complained mild and transient vomiting no side effects were noticed. All cases showed no abnormality in blood examination, liver function test and urinalysis. Both of the proglottids of D. ditremum and D. erinacei showed muscle relaxation in Tyrode solution containing 10(-4) g/ml of paromomycin sulfate. In D. ditremum the recovery of muscle tonus was observed within 10--15 minutes after affection of this drug, while the persistence of muscle relaxation was seen in D. erinacei. The activity of phosphoglucose isomerase was slightly inhibited by 10(-3) M paromomycin sulfate while those of hexokinase, phosphofructokinase and glucose-6-phosphate dehydrogenase were not inhibited. In phosphoenolpyruvate-succinate pathway, the activity of fumarate reductase was slightly inhibited 10(-3) M paromomycin sulfate while those of phosphoenolpyruvate carboxykinase and malate dehydrogenase were not inhibited.
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PMID:[Efficacy of paromomycin sulfate against human cestodiasis and its pharmacological action on tapeworm in vitro]. 687 66

The in vitro differentiation of Trypanosoma brucei from bloodstream to procyclic (insect) forms is accompanied by diminishing variant surface glycoprotein (VSG) and increasing levels of procyclin and phosphoenolpyruvate carboxykinase (PEPCK). In this study, we examined the fate of several glycolytic enzymes of T. brucei during differentiation. We observed a down-regulation of glycosomal phosphoglycerate kinase (gPGK) during differentiation. In contrast, intracellular levels of glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH), aldolase (ALD), and phosphoglucoisomerase (PGI) remained unchanged during differentiation and apparently continued to be synthesized in the procyclic form. To determine the potential role of proteasomes and other proteases during the differentiation process, we tested the effect of lactacystin, a specific inhibitor of proteasome activity, and morpholinourea-Phe-homoPhe-benz-alpha-pyrone (P27), a selective inhibitor of cysteine proteases, on the in vitro differentiation of T. brucei. Cells differentiated normally in the presence of 1 microM lactacystin, which confirmed our previous observation that this differentiation does not require crossing any phase boundaries in the cell cycle (Mutomba and Wang, Mol Biochem Parasitol 1996;80:89-102). But the cells thus differentiated did not increase in number and retained gPGK. Cells differentiated under 2 microM P27 also proceeded at a normal rate but failed to multiply and retained gPGK. However, most of the differentiated cells under 2 microM P27 also retained VSG on the cell membrane surface and expressed higher levels of procyclin suggesting that a cysteine protease(s) may be involved in releasing VSG and partially reducing procyclin during differentiation. This cysteine protease(s) has been tentatively identified in the procyclic cells as a 48 kDa protein through labeling of cysteine protease(s) with a biotinylated P27 homolog K02 (morpholinourea-Phe-homoPhe-vinylsulfone).
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PMID:The role of proteolysis during differentiation of Trypanosoma brucei from the bloodstream to the procyclic form. 966 24

The physiological and metabolic responses to gnd knockout in Escherichia coli K-12 was quantitatively investigated by using the (13)C tracer experiment (GC-MS/NMR) together with the enzyme activity analysis. It was shown that the general response to the gene knockout was the local flux rerouting via Entner-Doudoroff pathway and the direction reversing via non-oxidative pentose phosphate pathway (PPP). The mutant was found to direct higher flux to phosphoglucose isomerase reaction as compared to the wild-type, but the respiratory metabolism was comparable in both strains. The anaplerotic pathway catalyzed by malic enzyme was identified in the mutant, which was accompanied with an up-regulation of phosphoenolpyruvate carboxylase and down-regulation of phosphoenolpyruvate carboxykinase. The presented results provide first evidence that compensatory mechanism existed in PPP and anaplerotic pathway in response to the gnd deletion.
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PMID:Analysis of metabolic and physiological responses to gnd knockout in Escherichia coli by using C-13 tracer experiment and enzyme activity measurement. 1267 Jun 95

An integrated study on cell growth, enzyme activities and carbon flux redistribution was made to investigate how the central metabolism of Escherichia coli changes with the knockout of genes in the oxidative pentose phosphate pathway (PPP). Mutants deficient in glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase were constructed by disrupting the zwf and gnd genes and were grown in minimal media with two different carbon sources, such as glucose or pyruvate. It was shown that the knockout of either gnd or zwf gene did not affect the cell growth rate significantly, but the cellular metabolism was changed. While the specific substrate uptake rate and the specific carbon dioxide evolution rate for either mutant grown on glucose were higher than those obtained for the parent strain, these two rates were markedly decreased in mutants grown on pyruvate. The measurement of enzyme activities implied a significant change in metabolism, when alternative pathways such as the Entner-Doudoroff pathway (EDP) and the malic enzyme pathway were activated in the gnd mutant grown on glucose. As compared with the parent strain, the activities of phosphoglucose isomerase were increased in mutants grown on glucose but decreased in mutants grown on pyruvate. The metabolic flux redistribution obtained based on 13C-labeling experiments further indicated that the direction of the flux through the non-oxidative PPP was reversed in response to the gene knockout. Moreover, the knockout of genes caused an increased flux through the tricarboxlic acid cycle in mutants grown on glucose but caused a decrease in the case of using pyruvate. There was also a negative correlation between the fluxes through malic enzyme and isocitrate dehydrogenase in the mutants; and a positive correlation was found between the fluxes through malic enzyme and phosphoenolpyruvate carboxylase.
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PMID:Global metabolic response of Escherichia coli to gnd or zwf gene-knockout, based on 13C-labeling experiments and the measurement of enzyme activities. 1466 Nov 15

Mesembryanthemum crystallinum, a halophilic, inducible Crassulacean acid metabolism (CAM) species, was grown at NaCl concentrations of 20 and 400 millimolar in the rooting medium. Plants from the low salinity treatment showed exclusively C(3)-photosynthetic net CO(2) fixation, whereas plants exposed to the high salinity level exhibited net CO(2) dark fixation involving CAM. Mesophyll protoplasts, isolated from both tissues, were gently ruptured, and the intracellular localization of enzymes was studied following differential centrifugation and Percoll density gradient centrifugation of protoplast extracts. Both centrifugation techniques resulted in the separation of intact chloroplasts, with up to 90% yield, from other organelles and the nonparticulate fraction of cells. Enzymes were identified by determination of activity and by sodium dodecyl sulfate gel electrophoresis of enzyme protein.Experiments established the extraorganellar (cytoplasmic) location of phosphoenolpyruvate carboxylase, enolase, phosphoglyceromutase, and NADP-malic enzyme; the mitochondrial location of NAD-malic enzyme; and the chloroplastic location of pyruvate, Pi dikinase. NAD-glyceraldehyde-3-phosphate dehydrogenase, phosphohexose isomerase, and phosphoglycerate kinase were associated with both cytoplasm and chloroplasts. NADP-dependent malate dehydrogenase activity was found in both the chloroplastic and extrachloroplastic fractions; the activity in the chloroplast showed an optimum at pH 8.0 and was dependent upon preincubation of enzyme with dithiothreitol. The extrachloroplastic activity showed an optimum at pH 6.5 and was independent of pretreatment with dithiothreitol. Protoplast extracts of M. crystallinum performing CAM exhibited higher activities (expressed per mg chlorophyll per min) of phosphoenolpyruvate carboxylase, pyruvate, Pi dikinase, NADP-malic enzyme, NAD-malic enzyme, NADP-malate dehydrogenase, enolase, phosphoglyceromutase, NAD-glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and phosphohexose isomerase than protoplast extracts from M. crystallinum not exhibiting CAM. The increase in total activity of the latter three enzymes following exposure of plants to 400 millimolar NaCl and the development of CAM was due to specific increases in the levels of activity in the cytoplasm.
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PMID:Intracellular Localization of Enzymes of Carbon Metabolism in Mesembryanthemum crystallinum Exhibiting C(3) Photosynthetic Characteristics or Performing Crassulacean Acid Metabolism. 1666 97


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