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:4.1.1.32 (phosphoenolpyruvate carboxykinase)
4,204 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cell suspensions of Bacteroides fragilis were allowed to ferment glucose and lactate labeled with (14)C in different positions. The fermentation products, propionate and acetate, were isolated, and the distribution of radioactivity was determined. An analysis of key enzymes of possible pathways was also made. The results of the labeling experiments showed that: (i) B. fragilis ferments glucose via the Embden-Meyerhof pathway; and (ii) there was a randomization of carbons 1, 2, and 6 of glucose during conversion to propionate, which is in accordance with propionate formation via fumarate and succinate. The enzymes 6-phosphofrucktokinase (pyrophosphate-dependent), fructose-1,6-diphosphate aldolase, phosphoenolpyruvate carboxykinase, malate dehydrogenase, fumarate reductase, and methylmalonyl-coenzyme A mutase could be demonstrated in cell extracts. Their presence supported the labeling results and suggested that propionate is formed from succinate via succinyl-, methylmalonyl-, and propionyl-coenzyme A. From the results it also is clear that CO(2) is necessary for growth because it is needed for the formation of C4 acids. There was also a randomization of carbons 1, 2, and 6 of glucose during conversion to acetate, which indicated that pyruvate kinase played a minor role in pyruvate formation from phosphoenolpyruvate. Phosphoenolpyruvate carboxykinase, oxaloacetate decarboxylase, and malic enzyme (nicotinamide adenine dinucleotide phosphate-dependent) were present in cell extracts of B. fragilis, and the results of the labeling experiments agreed with pyruvate synthesis via oxaloacetate and malate if these acids are in equilibrium with fumarate. The conversion of [2-(14)C]- and [3-(14)C]lactate to acetate was not associated with a randomization of radioactivity.
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PMID:Pathway of succinate and propionate formation in Bacteroides fragilis. 14 60

Acetyl-coenzyme A carboxylase from Euglena gracilis strain Z was isolated as a component of a multienzyme complex which includes phosphoenolpyruvate carboxylase and malate dehydrogenase. The multienzyme complex was shown to exist in crude extracts and was purified to a homogeneous protein with a molecular weight of 360,000 by gel filtration. The ratio of the activities of the constituent enzymes was acetyl-CoA carboxylase:phosphoenolpyruvate carboxylase:malate dehydrogenase, 1:25:500. The complex is proposed to operate in conjunction with malic enzyme, which is present in Euglena, to facilitate the formation of substrates, malonyl-CoA, and NADPH, for fatty acid biosynthesis. The interaction of the enzymes may represent a means of control of acetyl-CoA carboxylase activity in organisms which do not possess an enzyme subject to allosteric regulation. The acetyl-CoA carboxylase activity from Euglena is unaffected by citrate and isocitrate.
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PMID:A multienzyme complex for CO2 fixation. 23 76

A multienzyme complex from Euglena, molecular weight about 360,000, containing phosphoenolpyruvate carboxylase, malate dehydrogenase, and acetyl-coenzyme A carboxylase has been dissociated into active constituent enzymes. The respective molecular weights are 183,000, 67,000, and 127,000. The malate dehydrogenase contained in the complex is electrophoretically distinct from other malate dehydrogenase isozymes found in Euglena. The K-m for HCO3minus of the free and complexed acetyl-CoA carboxylase is 4.2-5.4 mM, and the substrate dependency for acetyl-CoA describes a sigmoidal relationship. The HCO3minus K-m for the free phosphoenolpyruvate carboxylase is 7.3-5.4 mM while that for the same enzyme contained in the complex is 0.7-1.3 mM. Both the free and complexed forms ofphosphoenolpyruvate carboxylase have a K-m for phosphoenolpyruvate of 0.9-1.7 mM. The latter enzyme in both the complex and free forms is stimulated by NADH, acetyl-CoA, and ATP. In the free phosphoenolpyruvate carboxylase, the stimulation passes through a maximum depending on effector concentration. The effect of NADH is to increase V-max while K-m values remain unmodified.
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PMID:Dissociation and characterization of enzymes from a multienzyme complex involved in CO2 fixation. 23 77

1. Measurements are presented of the activity and intracellular distribution of phosphoenolypruvate carboxykinase, pyruvate carboxylase and NADP-malate dehydrogenase in rat, guinea-pig and rabbit liver and kidney cortex, together with previously obtained measurements of these enzymes in adipose tissue. 2. In all three tissues pyruvate carboxylase activity was greatest in the rat and lowest in the rabbit. 3. Guinea pig and rabbit were very similar to each other with respect to the extramitochondrial-mitochondrial distribution of phosphoenolpyruvate carboxykinase in all three tissues. 4. NADP-malate dehydrogenase was present in all three tissues in the rat, present in kidney cortex and adipose tissue in the guinea pig and absent from all tissues examines in the rabbit.
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PMID:The activities and intracellular distribution of nicotinamide-adenine dinucleotide phosphate-malate dehydrogenase, phosphoenolpyruvate carboxykinase and pyruvate carboxylase in rat, guinea-pig and rabbit tissues. 23 92

Yeast mutant lacking proteinase B activity have been isolated [Wolf, D. H. and Ehmann, C. (1978) FEBS Lett. 92, 121--124]. One of these mutants (HP232) is characterized in detail. Absence of the vacuolar localized enzyme is confirmed by checking for proteinase B activity in isolated mutant vacuoles. Defective proteinase B activity segregates 2:2 in meiotic tetrads. The mutation is shown to be recessive. Mutant proteinase B activity is not only absent against the synthetic substrate. Azocoll, but also against the physiological substrate pre-chitin synthetase, cytoplasmic malate dehydrogenase and fructose-1,6-bisphosphatase. The mutant shows normal vegetative growth, a phenomenon not consistent with the idea that proteinase B might be the activating principle of chitin synthetase zymogen in vivo. Fluorescence microscopy shows normal chitin insertion. Enzymes underlying carbon-catabolite inactivation in wild-type cells (a mechanism proposed to be possibly triggered by proteinase B) such as cytoplasmic malate dehydrogenase, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase and isocitrate lyase, are inactivated also in the mutant. NADP-dependent glutamate dehydrogenase, which is found to be inactivated in glucose-starved wild-type cells, proceeds normally in the mutant. Mutant cells show more than 40% reduced protein degradation under starvation conditions. Sporulating diploids, homozygous for proteinase B absence, also exhibit an approximately 40% reduced protein degradation as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene. The time of the appearance of the first ascospores of diploid cells, homozygous for proteinase B deficiency, is delayed about 50% and sporulation frequency is reduced to about the same extent as compared to homozygous wild-type diploids or diploids heterozygous for the mutant gene.
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PMID:Studies on a proteinase B mutant of yeast. 38 14

An investigation of the carbohydrate energy metabolism of Rhabdias bufonis, the lung-dwelling nematode parasite of the African toad, Bufo regularis, indicates that the nematode stores very little glycogen (0.137 +/- 0.003% on a fresh weight basis) but does utilize oxygen in vitro. The intracellular distribution and high levels of activity observed for the enzymes phosphoenolpyruvate carboxykinase, pyruvate kinase, lactate dehydrogenase, malate dehydrogenase, malic enzyme and fumarate reductase suggest two alternative pathways of carbohydrate energy metabolism.
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PMID:Respiration and carbohydrate energy metabolism of the lung-dwelling parasite Rhabdias bufonis (Nematoda: Rhabdiasoidea). 56 16

The dynamics of label distribution was studied in the products of 14CH3OH assimilation by the cells of Pseudomonas gazotropha Z-1156. Substances to be first detected were glycolate, glycine and those of the chromatogram "start" spot. Later, the radioactivity was detected in phosphorylated compounds and glycerate. Cell extracts of Ps. gazotropha Z-1156 contained ribosephosphate isomerase, phosphoribulokinase and glyceraldehyde dehydrogenase but not ribulosediphosphate carboxylase. Distribution of the label in the products of 14CH3OH assimilation and the presence of active hydroxypyruvate reductase in the extract suggest that the serine cycle is involved in methylotrophy of Ps. gazotropha Z-1156. This suggestion is confirmed by the presence of active formate dehydrogenase, phosphoenolpyruvate carboxylase, (NADP+, Mn2+)-specific isocitrate dehydrogenase, (NAD, Mg2+)-specific malate dehydrogenase, malate lyase, and isocitrate lyase. The citric acid cycle is open at the alpha-ketoglutarate dehydrogenase system. The dry biomass of Ps. gazotropha Z-1156 contains over 70% of protein.
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PMID:[Carbon assimilation pathways in the methylotrophy of Pseudomonas gazotropha]. 70 43

1. Measurements have been made of the activities of enzymes of the glycolytic route, the pentose phosphate pathway, the tricarboxylic acid cycle and lipogenesis in liver and adipose tissue from genetically obese (fa/fa) rats and their lean litter mates (fa/ --). The effect of food restriction for a period of three weeks on the enzyme profile of liver and adipose tissue of the obese rat was also studied. 2. The most striking increases in enzyme activity in livers from obese rats were: (a) among enzymes of lipogenesis; ATP-citrate lyase, acetyl-CoA carboxylase, fatty acid synthetase, malate dehydrogenase (decarboxylating) and cytoplasmic glycerolphosphate dehydrogenase; (b) within the pentose phosphate pathway; glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase; (c) within the glycolytic pathway; glucokinase, pyruvate kinase and lactate dehydrogenase. All of these enzymes showed a significant increase in activity on the basis of U/g liver and U/mg DNA. In adipose tissue all the enzymes of lipogenesis, of the glycolytic route, of the oxidative segment of the pentose phosphate pathway and of the tricarboxylic acid cycle were increased when expressed as U/2 fat pads or as U/mg DNA. 3. The restriction of the food intake of obese rats to that consumed by their lean litter mates for periods of three weeks did not produce the expected adaptive decrease in enzymes of lipogenesis; in adipose tissue, only ATP-citrate lyase and malate dehydrogenase (decarboxylating) showed a marked decrease; no significant change was found in adipose tissue or liver of the activities of acetyl-CoA carboxylase and fatty acid synthetase, when expressed on a cell basis (U/mg DNA). The non-oxidative enzymes of the pentose phosphate pathway and enzymes involved in glycerogenesis (pyruvate carboxylase, malate dehydrogenase and phosphoenolpyruvate carboxykinase) all increased in adipose tissue from limit-fed obese rats. 4. The rate of conversion of specifically labelled glucose to (14C)O2 and 14C-labelled lipid by pieces of adipose tissue and by liver slices was also measured. Insulin caused an increase in the conversion of (1-14C)glucose to (14C)O2 and 14C-labelled lipid in obese rats fed ad libitum, limit-fed rats and in their lean litter mates. 5. The results are discussed in relation to the raised insulin and hypothyroid state of the obese rat. The effect of this altered hormonal status on the activity of cyclic nucleotide phosphodiesterases and cellular levels of adenosine 3' :5'-monophosphate and guanosine 3' :5'-monophosphate and guanosine 3' :5'-monophosphate in relation to the obese syndrome is considered.
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PMID:Adaptive responses of enzymes of carbohydrate and lipid metabolism to dietary alteration in genetically obese Zucker rats (fa/fa). 71 Mar 95

In order to assess the extent to which metabolism within the sheep placenta may influence the transfer of metabolites between mother and foetus at different stages of gestation the activities of enzymes concerned with some aspects of carbohydrate, amino acid and keton body metabolism were determined in placental cotyledons resected from ewes during the last three months of pregnancy. The activities of pyruvate kinase (EC 2.7.1.40), lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37), ATP citrate (pro-3S)-lyase (EC 4.1.3.8), citrate (si)-synthase (EC 4.1.3.7), acetyl-CoA synthetase (EC 6.2.1.1), acetyl-CoA acetyltransferase (EC 2.3.1.9) and 3-keto acid CoA-transferase (EC 2.8.3.5) per gram wet weight cotyledon do not change during the period studied. The activities of alanine aminotransferase (EC 2.6.1.2), aspartate aminotransferase (EC 2.6.1.1), isocitrate dehydrogenase (NADP+) (EC 1.1.1.42), ornithine-oxoacid aminotransferase (EC 2.6.1.13) and 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) show an increase in activity between the third and fourth months of pregnancy whilst the activities of arginase (EC 3.5.3.1) and possibly pyruvate carboxylase (EC 6.4.1.1) show an increase in activity between the fourth and final months of pregnancy. Ornithine decarboxylase (EC 4.1.1.17) activity declines to one tenth of its activity during this later period. The absence of detectable activities of phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and ornithine carbamoyltransferase (EC 2.1.3.3) indicate that gluconeogenesis and urea synthesis from ammonia do not occur in the sheep placenta. It appears that the ability of the placenta to metabolise several substrates is achieved by the time the placenta reaches its maximum size at approximately 90 days.
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PMID:Enzyme activities in the sheep placenta during the last three months of pregnancy. 84 73

The effect of age and nutritional status on the synthesis of fatty acids from a variety of labeled substrates by human adipose tissue in vitro was investigated. The results of this study clearly demonstrate that, although human adipose tissue is able to oxidize glucose to CO2, its ability to incorporate glucose-carbon into long chain fatty acids is negligible. Although the utilization of acetate for the synthesis of fatty acids by adipose tissue is substantial in the presence of glucose and insulin, its physiologic significance in human under normal dietary conditions is questionable. That the capacity of human adipose tissue is limited is further supported by (1) a negligible incorporation of pyruvate-3-14C (up to 25 mM concentration in the incubation medium) into fatty acids, (2) a lack of stimulation in lipogenesis by human adipose tissue after refeeding a diet high in carbohydrate and very low in fat to a previously starved human, and (3) an extremely low activity of pyruvate carboxylase and ATP-citrate lyase in adipose tissues from humans of varying ages. The activities of other key lipogenic enzymes, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and NADP-malate dehydrogenase, are also low. These enzymes can be stimulated in human adipose tissue after a fasting-refeeding regimen. The activity of phosphoenolpyruvate carboxykinase is also very low in human adipose tissue,and it is suggested that a pathway of glyceroneogenesis may not play a significant role in human adipose tissue. In light of our results, together with previous reports, it is possible to conclude that the capacity of human adipose tissue to utilize a dietary carbohydrate for the synthesis of fatty acids is extremely low and that the liver plays a major role in the biosynthesis of endogenous fatty acids from dietary carbohydrate in the human.
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PMID:Fatty acid synthesis by human adipose tissue. 111 80


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