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)

During the first 72 h after 67% partial hepatectomy of female Wistar rats (160 g) the specific activities [mumol X min-1 X (g liver)-1] of the glucogenic glucose-6-phosphatase and fructose-bisphosphatase and of the glycolytic hexokinase and 6-phosphofructokinase remained essentially constant. However, the activity of the glycolytic pyruvate kinase (L- plus M2-type) was decreased slightly and that of glucokinase was decreased markedly to below 30%, while the glucogenic phosphoenolpyruvate carboxykinase was increased to over 200%. Between 10 and 40 h after partial hepatectomy, when the proliferation started in the periportal area, a shift of the glucogenic glucose-6-phosphatase-rich zone from its normal periportal to an intermediate or even perivenous position was observed histochemically. After 48 h, when the proliferation was no longer restricted to the periportal zone, the normal glucose-6-phosphatase zonation (as before partial hepatectomy) was restored. Glycogen was degraded rapidly during the first 4 h after operation; it was later repeatedly resynthesized and degraded in correlation with the feeding rhythm of the animals. The zonation of glycogen metabolism was in accord with the observed zonation of glucose-6-phosphatase.
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PMID:Increase of the gluconeogenic and decrease of the glycolytic capacity of rat liver with a change of the metabolic zonation after partial hepatectomy. 21 1

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

This work was carried out to investigate the relative roles of phosphofructokinase and pyrophosphate-fructose-6-phosphate 1-phosphotransferase during the increased glycolysis at the climacteric in ripening bananas (Musa cavendishii Lamb ex Paxton). Fruit were ripened in the dark in a continuous stream of air in the absence of ethylene. CO2 production, the contents of glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-bisphosphate, phosphoenolpyruvate and PPi; and the maximum catalytic activities of pyrophosphate-fructose-6-phosphate 1-phosphotransferase, 6-phosphofructokinase, pyruvate kinase and phosphoenolpyruvate carboxylase were measured over a 12-day period that included the climacteric. Cytosolic fructose-1,6- bisphosphatase could not be detected in extracts of climacteric fruit. The peak of CO2 production was preceded by a threefold rise in phosphofructokinase, and accompanied by falls in fructose 6-phosphate and glucose 6-phosphate, and a rise in fructose 1,6-bisphosphate. No change in pyrophosphate-fructose-6-phosphate 1-phosphotransferase or pyrophosphate was found. It is argued that phosphofructokinase is primarily responsible for the increased entry of fructose 6-phosphate into glycolysis at the climacteric.
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PMID:Glycolysis at the climacteric of bananas. 184 21

Cell-free extracts of two strictly anaerobic mollicutes, Anaeroplasma intermedium 5LA and Asteroleplasma anaerobium 161T, were tested for enzymic activities of intracellular carbohydrate metabolism. Asteroleplasma anaerobium was also tested for enzymes of purine and pyrimidine metabolism. Both organisms had enzymic activities associated with the nonoxidative portion of the pentose phosphate pathway, and with the Embden-Meyerhoff-Parnas pathway. The 6-phosphofructokinase (PFK) of Asteroleplasma anaerobium was ATP-dependent, whereas the PFK of Anaeroplasma intermedium was PPi-dependent. The two anaerobic mollicutes also differed with respect to the enzymes that converted phosphoenolpyruvate (PEP) to pyruvate; Anaeroplasma intermedium had pyruvate kinase activity, but Asteroleplasma anaerobium had pyruvate, orthophosphate dikinase activity (PPi-dependent). Both organisms had lactate dehydrogenase activity which was activated by fructose 1,6-bisphosphate (Fru-1,6-P2). Anaeroplasma intermedium had activity for PEP carboxykinase (activated by Fru-1,6-P2), but Asteroleplasma anaerobium did not. PEP carboxytransphosphorylase activity was not detected in either organism. Anaeroplasma intermedium had malate dehydrogenase and isocitrate dehydrogenase activities, but it had no activities for the three other tricarboxylic acid cycle enzymes examined; Asteroleplasma anaerobium had malate dehydrogenase activity only. Asteroleplasma anaerobium had enzymic activities for the interconversion of purine nucleobases, (deoxy)ribonucleosides, and (deoxy)ribomononucleotides, including PPi-dependent nucleoside kinase, reported heretofore only in some other mollicutes. Asteroleplasma anaerobium could synthesize dTDP by the thymine salvage pathway if deoxyribose 1-phosphate was provided, and it had dUTPase, ATPase, and dCMP kinase activities. It lacked (deoxy)cytidine deaminase, dCMP deaminase, and deoxycytidine kinase activities.
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PMID:Enzymic activities of carbohydrate, purine, and pyrimidine metabolism in the Anaeroplasmataceae (class Mollicutes). 281 26

A mathematical model for circadian self-oscillation in the carbohydrate branch of energy metabolism (CEM) was analysed. The self-oscillations are due to the reciprocal regulation of the activities of 6-phosphofructokinase and fructose-1,6-bisphosphatase by fructose-1,6-bisphosphate. The circadian period was shown to be insensitive to metabolic disturbances because of the presence in CEM of negative feedback mechanisms regulating the activities of the key enzymes 6-phosphofructokinase, fructose-1,6-bisphosphatase, pyruvate kinase and phosphoenolpyruvate carboxykinase. It has been also shown that such mechanisms are largely synergistic in their action.
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PMID:[Mathematical model of stabilization of circadian rhythm in cell energy metabolism]. 358 Mar 95

Prolonged exercise increased the concentrations of the hexose phosphates and phosphoenolpyruvate and depressed those of fructose 1,6-bisphosphate, triose phosphates and pyruvate in the liver of the rat. Since exercise increases gluconeogenic flux, these changes in metabolite concentrations suggest that metabolic control is exerted, at least, at the fructose 6-phosphate/fructose 1,6-bisphosphate and phosphoenolpyruvate/pyruvate substrate cycles. Exercise increased the maximal activities of glucose 6-phosphatase, fructose 1,6-bisphosphatase, pyruvate kinase and pyruvate carboxylase in the liver, but there were no changes in those of glucokinase, 6-phosphofructokinase and phosphoenolpyruvate carboxykinase. Exercise changed the concentrations of several allosteric effectors of the glycolytic or gluconeogenic enzymes in liver; the concentrations of acetyl-CoA, ADP and AMP were increased, whereas those of ATP, fructose 1,6-bisphosphate and fructose 2,6-bisphosphate were decreased. The effect of exercise on the phosphorylation-dephosphorylation state of pyruvate kinase was investigated by measuring the activities under conditions of saturating and subsaturating concentrations of substrate. The submaximal activity of pyruvate kinase (0.5 mM-phosphoenolpyruvate), expressed as percentage of Vmax., decreased in the exercised animals to less than half that found in the controls. These changes suggest that hepatic pyruvate kinase is less active during exercise, possibly owing to phosphorylation of the enzyme, and this may play a role in increasing the rate of gluconeogenesis.
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PMID:Metabolic control of hepatic gluconeogenesis during exercise. 622 82

The metabolism of glutamine in resting and concanavalin-A-stimulated lymphocytes was investigated. In incubated lymphocytes isolated from rat mesenteric lymph nodes, the rates of oxygen and glutamine utilization and that of aspartate production were approximately linear with respect to time for 60 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 90 min. The major end products of glutamine metabolism were glutamate, aspartate and ammonia: the carbon from glutamine may contribute about 30% to respiration. When both glucose and glutamine were presented to the cells, the rates of utilization of both substances increased. Evidence was obtained that the stimulation of glycolysis by glutamine could be due, in part, to an activation of 6-phosphofructokinase. Starvation of the donor animal increased the rate of glutamine utilization. The phosphoenolpyruvate carboxykinase inhibitor mercaptopicolinate decreased the rate of glutamine utilization by 28%; the rates of accumulation of glutamate and ammonia were decreased, whereas those of lactate, aspartate and malate were increased. The mitogen concanavalin A increased the rate of glutamine utilization (by about 51%). The rate of [3H]thymidine incorporation into DNA caused by concanavalin A in cultured lymphocytes was very low in the absence of glutamine; it was increased about 4-fold at 1 microM-glutamine and was maximal at 0.3 mM-glutamine; neither other amino acids nor ammonia could replace glutamine.
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PMID:Glutamine metabolism in lymphocytes of the rat. 688 97

Histometric data obtained by the point counting method, and the enzyme patterns of glycolysis, gluconeogenesis, fatty degradation and energy transfer have been determined in the same muscle specimens of m. vastus lateralis from 12 untrained patients between the ages of 4 and 78 years who suffered no disturbance of the neuromuscular system. Activities of 18 enzymes have been related to pure muscle weight corrected for fatty and connective tissue content, as well as to single fibre weight. A comparable muscle enzyme pattern was found in persons of around 20 years old and around 70 years old when expressed per gram of single fibre weight. However, in terms of grams of pure muscle weight, a significant activity decrease with age was obtained for 6-phosphofructokinase, triosephosphate dehydrogenase and phosphoenolpyruvate carboxykinase, whereas activity of hexose diphosphatase increased with age as also did 3-hydroxyacyl-CoA dehydrogenase activity. Five other cytoplasmic enzyme activities involved in glycolysis and energy transfer did not change significantly with age, nor did lysosomal acid phosphatase. The mitochondrial enzyme activities of gluconeogenesis (for example, pyruvate carboxylase, malic enzyme) were diminished to a lesser extent as also the auxiliary enzymes glutamic-oxaloacetic transminase and glutamic-pyruvic transaminase; glutamate dehydrogenase activity remained unchanged. The findings indicate a distinct disorganization of cytoplasmic glycolysis and gluconeogenesis pathways in presenile human skeletal muscle, confirming the histometric data already described. They cannot be explained by changes with age in numerical or areal ratio of type I and type II fibres.
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PMID:Disorganization of glycolytic and gluconeogenic pathways in skeletal muscle of aged persons studied by histometric and enzymatic methods. 743 2

Campylobacter jejuni is unable to utilize glucose as a carbon source due to the absence of the key glycolytic enzyme 6-phosphofructokinase. The genome sequence of C. jejuni NCTC 11168 indicates that homologues of all the appropriate enzymes for gluconeogenesis from phosphoenolpyruvate (PEP) are present, in addition to the anaplerotic enzymes pyruvate carboxylase (PYC), phosphoenolpyruvate carboxykinase (PCK) and malic enzyme (MEZ). Surprisingly, a pyruvate kinase (PYK) homologue is also present. To ascertain the role of these enzymes, insertion mutants in pycA, pycB, pyk and mez were generated. However, this could not be achieved for pckA, indicating that PCK is an essential enzyme in C. jejuni. The lack of PEP synthase and pyruvate orthophosphate dikinase activities confirmed a unique role for PCK in PEP synthesis. The pycA mutant was unable to grow in defined medium with pyruvate or lactate as the major carbon source, thus indicating an important role for PYC in anaplerosis. Sequence and biochemical data indicate that the PYC of C. jejuni is a member of the alpha4beta4, acetyl-CoA-independent class of PYCs, with a 65.8 kDa subunit containing the biotin moiety. Whereas growth of the mez mutant was comparable to that of the wild-type, the pyk mutant displayed a decreased growth rate in complex medium. Nevertheless, the mez and pyk mutants were able to grow with pyruvate, lactate or malate as carbon sources in defined medium. PYK was present in cell extracts at a much higher specific activity [>800 nmol x min(-1) x (mg protein)(-1)] than PYC or PCK [<65 nmol x min(-1) x (mg protein)(-1)], was activated by fructose 1,6-bisphosphate and displayed other regulatory properties strongly indicative of a catabolic role. It is concluded that PYK may function in the catabolism of unidentified substrates which are metabolized through PEP. In view of the high K(m) of MEZ for malate (approximately 9 mM) and the lack of a growth phenotype of the mez mutant, MEZ seems to have only a minor anaplerotic role in C. jejuni.
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PMID:Analysis of gluconeogenic and anaplerotic enzymes in Campylobacter jejuni: an essential role for phosphoenolpyruvate carboxykinase. 1188 2

n-3 highly unsaturated fatty acids (n-3 HUFAs) have been shown to suppress lipid accumulation and improve protein utilization in grass carp; however, little is known about the underlying molecular mechanism. Hence, we analyzed the hepatopancreas transcriptome of grass carp (Ctenopharyngodon idellus) fed either lard oil (LO) or fish oil (FO) diets. RNA-seq data showed that 125 genes were significantly up-regulated and 107 were significantly down-regulated in the FO group. Among them, 17 lipid metabolism related genes, 12 carbohydrate metabolism related genes, and 34 protein metabolism related genes were selected. Lipid metabolism related genes, such as very long-chain acyl-CoA synthetase (ACSVL),carnitine O-palmitoyltransferase 1 (CPT1) and carnitine-acylcarnitine translocase (CACT), were up-regulated in the FO group. But the genes of diacylglycerol O-acyltransferase 2 (DGAT2) and stearoyl-CoA desaturase (SCD) were down-regulated. Down-regulation of glycolysis related genes, such as 6-phosphofructokinase (PFK), phosphoglycerate kinase (PGK) and pyruvate dehydrogenase kinase (PDK), added with up-regulation of gluconeogenesis related genes, such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), suggests lower utilization of carbohydrate of the FO group. Besides, dietary FO also influenced the protein metabolism related genes, such as up-regulation of genes involved in digestion of dietary protein, mRNA transcription, protein translation and amino acid utilization, down-regulation of genes involved in mRNA degradation and ubiquitination of protein. Interestingly, the up-regulation of mitochondrial uncoupling protein 2 (UCP2) and down-regulation of oxidative phosphorylation related genes (cytochrome c oxidase subunit 4 isoform 2 [COX4I2], HIG1 domain family member 1A [HIGD1A] and cytochrome-b5 reductase [CYB5R]) suggest that energy metabolism may be also influenced by dietary fatty acid composition. These findings presented here provide a comprehensive understanding of the molecular mechanisms governing the effects of fish oil in grass carp.
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PMID:Comparative analysis of the hepatopancreas transcriptome of grass carp (Ctenopharyngodon idellus) fed with lard oil and fish oil diets. 2586


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