Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.1.1.49 (phosphoenolpyruvate carboxykinase)
4,654 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By means of the microdissection technique applied on kidney tissue, the following results were obtained: Hexokinase, an enzyme of glycolysis, revealed a low activity in the proximal and a high activity in the distal tubule. This distribution pattern is consistent with the finding that glucose is the main fuel for the distal tubule. Glucose-6-phosphatase, an enzyme of gluconeogenesis, demonstrates a significant activity in the distal tubule and in the glomerulus. Both structures are, however, no glucose producers. Phosphoenolpyruvate carboxykinase, the key enzyme of gluconeogenesis, is found only in the segments of the proximal tubule. The distal tubule lacks any activity. This is also the case during starvation and metabolic acidosis when gluconeogenesis is stimulated. Glutamic dehydrogenase, -an enzyme possibly connected with ammoniagenesis-, malate- and lactate dehydrogenase-, enzymes involved with hydrogen transfer through the mitochondrial membrane-, showed a close parallelism to phosphoenolpyruvate carboxykinase in their distribution along the proximal tubule. The bidirectional function of glyceraldehyde-P dehydrogenase is well documented by the close correlation to phosphoenolpyruvate carboxykinase (gluconeogenesis) in the proximal tubule and to pyruvic kinase (glycolysis) in the distal tubule.
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PMID:Metabolic patterns in various structures of the rat nephron. The distribution of enzymes of carbohydrate metabolism. 17 83

Optimal concentrations of the essential components for analyzing the activity of each enzyme associated with glycolysis and gluconeogenesis in rabbit periodontal ligament were examined, and enzyme assay systems for 15 enzymes including 22 reactions were established using triethanolamine buffer. Specific activities of all the enzymes, except for the gluconeogenic reaction of phosphoglycerate kinase, were systematically evaluated using the optimum buffer for each enzyme, since the activity of each enzyme varied depending on the buffer used. For glycolysis, the activity levels of hexokinase and 6-phosphofructokinase were very low, and consequently these enzyme reactions were inferred to be the rate-limiting steps. For gluconeogenesis, fructose 1,6-bisphosphatase and aldolase activities were extremely low, and the activities of glucose 6-phosphatase, phosphoenolpyruvate carboxykinase and pyruvate carboxylase were undetectable. These results suggest that the periodontal ligament may have no gluconeogenesis capability. With a rise in pH, the activities of the key enzymes of glycolysis gradually increased, and a specific "crossover" point was found between the activities of glyceraldehyde-phosphate dehydrogenase and phosphoglyceromutase. In addition, the activity of fructose 1,6-bisphosphatase, one of the key enzymes of gluconeogenesis, was markedly increased with a rise in pH, although pH changes had no effect on aldolase activity. Consequently, alkaline pH appeared to result in overall stimulation of glycolysis.
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PMID:Enzymatic regulation of glycolysis and gluconeogenesis in rabbit periodontal ligament under various physiological pH conditions. 165 53

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

The compartmentation of key processes in sugar, organic acid and amino acid metabolism was studied during the development of the flesh and seeds of grape (Vitis vinifera L.) berries. Antibodies specific for enzymes involved in sugar (cell wall and vacuolar invertases, pyrophosphate: fructose 6-phosphate phosphotransferase, aldolase, NADP-glyceraldehyde-P dehydrogenase, cytosolic fructose 1,6-bisphosphatase), photosynthesis (Rubisco, fructose 1,6-bisphosphatase, sedoheptulose 1,7-bisphosphatase), amino acid metabolism (cytosolic and mitochondrial aspartate aminotransferases, alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase), organic acid metabolism (phosphoenolpyruvate carboxylase, NAD- and NADP-dependent malic enzyme, ascorbate peroxidase), and lipid metabolism (acetyl CoA carboxylase, isocitrate lyase) were used to determine how their abundance changed during development. There were marked changes in the abundance of many of these enzymes in both the flesh and seeds. The intercellular location of some enzymes was investigated using immunohistochemistry. Several enzymes (e.g. phosphoenolpyruvate carboxylase and those involved in amino acid metabolism) were associated with tissues likely to function in the transport of imported assimilates, such as the vasculature. Although other enzymes (e.g. NADP-malic enzyme and soluble acid invertase, involved in the metabolism of sugars and organic acids) were largely present in the parenchyma cells of the flesh, their distribution was extremely heterogeneous. This study shows that when considering the metabolism of complex structures such as fruit, it is essential to consider how metabolism is compartmentalized between and within different tissues, even when they are apparently structurally homogeneous.
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PMID:An immunohistochemical study of the compartmentation of metabolism during the development of grape (Vitis vinifera L.) berries. 1093 59

Callus cultures of Arabidopsis thaliana (cv. Columbia) in Petri dishes were exposed to altered g-forces by centrifugation (1-10 g). Using semi-quantitative RT-PCR transcripts of genes coding for metabolic key enzymes (ADP-glucose pyrophosphorylase, ADPG-PP; beta-amylase, fructose-1,6-bisphosphatase, FBPase; glyceraldehyde-P dehydrogenase, GAPDH; hydroxymethylglutaryl-CoA reductase, HMG; phenylalanine-ammonium-lyase, PAL; PEP carboxylase, PEPC) were used to monitor threshold conditions for g-number (all) and time of exposure (beta-amylase) which led to altered amounts of the gene product. Exposure to approximately 5 g and higher for 1 h resulted in altered transcript levels: transcripts of beta-amylase, PAL, and PEPC were increased, those of ADPG-PP decreased, while those of FBPase, GAPDH, and HMG were not affected. This probably indicates a shift from starch synthesis to starch degradation and increased rates of anaplerosis (PEPC: supply of ketoacids for amino acid synthesis). In order to get more information about g-related effects on gene expression, we used a 1-h exposure to 7 g for a microarray analysis, using a commercial A. thaliana chip with 4105 unique annotated clusters/genes (IncyteGenomics). Transcripts of more than 200 genes were significantly increased in amount (ratio 7 g/1 g control; 2(1.6) and larger). They fall into several categories. Transcripts coding for enzymes of major pathways form the largest group (25%), followed by gene products involved in cellular organization and cell wall formation/rearrangement (17%), signalling, phosphorylation/dephosphorylation (12%), proteolysis and transport (10% each), hormone synthesis plus related events (8%), defense (4%), stress-response (2%), and gravi-sensing (2%). Many of the alterations are part of a general stress response, but some changes related to the synthesis/rearrangement of cell wall components could be more hyper-g-specific. We only found few gene products, which were decreased in relation to 1 g controls, and these were less significant (ratio < 2(1.6)). We thus assume that g-forces above a threshold of about 5 g for 1 h are sensed by plant cells in general, causing distinct metabolic responses, which obviously in part, are regulated by gene expression.
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PMID:Hyper-gravity effects on the Arabidopsis transcriptome. 1455 51

The activities of certain enzymes related to the carbon assimilation pathway in whole leaves, mesophyll cell extracts, and bundle sheath extracts of the C(4) plant Panicum miliaceum have been measured and compared on a chlorophyll basis. Enzymes of the C(4) dicarboxylic acid pathway-phosphoenolpyruvate carboxylase and NADP-malic dehydrogenase-were localized in mesophyll cells. Carbonic anhydrase was also localized in mesophyll cell extracts. Ribose 5-phosphate isomerase, ribulose 5-phosphate kinase, and ribulose diphosphate carboxylase-enzymes of the reductive pentose phosphate pathway-were predominantly localized in bundle sheath extracts. High activities of aspartate and alanine transaminases and glyceraldehyde-3-P dehydrogenase were found about equally distributed between the photosynthetic cell types. P. miliaceum had low malic enzyme activity in both mesophyll and bundle sheath extracts.Isolated bundle sheath cells were capable of converting aspartate to oxalacetate at rates approaching the aspartate transaminase activity of bundle sheath extracts. The bundle sheath cells had a light induced CO(2) fixation of 23 mumoles of CO(2)/mg chl.hr in the absence of exogenous substrates.The photorespiratory enzymes, hydroxypyruvate reductase and glycolic oxidase, were about 3 fold higher in bundle sheath extracts than in mesophyll extracts when compared on a chlorophyll basis.
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PMID:Metabolic Activities in Extracts of Mesophyll and Bundle Sheath Cells of Panicum miliaceum (L.) in Relation to the C(4) Dicarboxylic Acid Pathway of Photosynthesis. 1665 52

The mutation of a nuclear gene in peanut (Arachis hypogaea L.) plants results in a reduced light-dependent development of chloroplast fine structure, soluble protein, ribulose-1, 5-diP carboxylase, NADP-glyceraldehyde-3-P dehydrogenase, fructose-1, 6-diP aldolase, glycerate-3-P kinase, phosphoenolpyruvate carboxylase, malate dehydrogenase, and dark respiration during the 72-hour lag period of chlorophyll synthesis in dark-grown leaves exposed to continuous light. The mutation has pleiotropic affects. Kinetic analysis shows there is also a 72-hour lag period in the light-dependent development of NADP-glyceraldehyde-3-P dehydrogenase and fructose-1, 6-diP aldolase in the mutant leaves, whereas there is no lag in the development of NAD-malate dehydrogenase and dark respiration. There is minimal development of the chloroplast during the 72-hour mutationally induced lag period, but there is pronounced cytoplasmic and mitochondrial activity during this phase. There is a 24-hour lag period in the light-dependent enlargement of the mutant leaves. At the completion of leaf enlargement, chloroplast differentiation is initiated. The mutation does not result in any chloroplast deletions, it only affects the timing of the synthesis of these components.Elimination of the lag period in leaf enlargement and chloroplast development (potentiation) requires a preliminary 72- to 96-hour dark period before exposing the dark-grown leaves to continuous light. There is extensive development of the etioplasts during this dark period. These results establish that the nuclear gene mutation affects the early stages of plastid development and not the light-dependent synthesis of plastid components. The nuclear gene may code for the regulation of the synthesis of a component (nutrient) in the dark (or during the lag phase in the light) which is essential for the development of mesophyll cells and plastids. Although, the chloroplast is a semi-autonomous organelle, nuclear gene control of chloroplast differentiation may not be independent of cellular growth.
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PMID:Elimination of the lag period in chloroplast development in a chlorophyll mutant of peanuts. 1665 82

In the polyol producing plant, celery (Apium graveolens L.), mannitol is a major photosynthetic product and a form in which carbohydrate is translocated. Measurements of whole leaf extracts of celery indicated substantial activity of the following enzymes: mannose-6-P reductase, mannose-6-P isomerase, mannitol-1-P phosphatase, and nonreversible glyceraldehyde-3-P dehydrogenase. The activities of these enzymes were either undetectable or very low in the nonpolyol producing plants, Secale cereale L. (rye) and Vigna mungo (L.) Hepper (black gram).Mesophyll protoplasts were enzymically isolated from celery leaves, broken with a Yeda press and the intracellular localization of the above enzymes for mannitol synthesis studied following differential and/or sucrose density gradient centrifugation of the protoplast extract. These data suggested the enzymes involved in mannitol synthesis are exclusively localized in the cytoplasm. Ninety-five to 100% of the activity of these enzymes, along with the cytoplasmic marker enzyme phosphoenolpyruvate carboxylase, was found in the cytosolic fraction.We propose the pathway of photosynthetic carbon flow from triose-P to mannitol in celery occurs via fructose-6-P, mannose-6-P, and mannitol-1-P; these final reactions being catalyzed by the cytoplasmic enzymes, mannose-6-P isomerase, NADPH-dependent mannose-6-P reductase, and mannitol-1-P phosphatase, respectively. The requirement for NADPH may be met via the cytoplasmically located NADP-linked nonreversible glyceraldehyde-3-P dehydrogenase.
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PMID:A pathway for photosynthetic carbon flow to mannitol in celery leaves : activity and localization of key enzymes. 1666 32

The activities of NADP: glyceraldehyde-phosphate dehydrogenase (GAPDH), an enzyme complex comprising of phosphoglycerate kinase (EC 2.7.2.3) and glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.13), and phosphoenolpyruvate carboxylase (PEPK; EC 4.1.1.31) in seedlings and leaves of wheat (Triticum aestivum L.) plants of the cultivars Mironovskaya 808 and Lutescens 758 have been compared under conditions of normal water supply, water deficiency, and subsequent rehydration. GAPDH activity, which determines the carbohydrate route of photosynthetic metabolism at the initial stages, is decreased by water stress to a greater extent than that of PEPK, on the activity of which non-carbohydrate metabolic pathways depend. Pretreatment of seedlings and mature plants with natural (6-benzylaminopurine) and synthetic (tidiazuron, kartolin-2, and kartolin-4) cytokinins attenuates the loss of enzyme activities during drought and facilitates their recovery within the period of rehydration; both effects are underlain by augmentation of reparation processes. The relative intensification of non-carbohydrate pathways of photosynthetic metabolism, observed under conditions of water deficiency, is accompanied by an increase in the osmotic pressure of cell sap. Possible mechanisms of this protector effect of cytokinin preparations are discussed.
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PMID:[Activity of NADP-dependent glyceraldehyde-phosphate dehydrogenase and phosphoenolpyruvate carboxylase in wheat leaves under water stress]. 1687 54


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