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)

1. The ratio of the combined activities of hexokinase (EC 2.7.1.1) and glucokinase (EC 2.7.1.2) to the activity of glucose-6-phosphatase (EC 3.1.3.9) changed in favour of the glycolytic enzymes during pregnancy and at peak lactation. 2. There were no important changes in the ratio of the activity of phosphofructokinase (EC 2.7.1.11) to that of fructose diphosphatase (EC 3.1.3.11). 3. The ratio of the activity of pyruvate kinase (EC 2.7.1.40) to the combined activities of phosphoenolpyruvate carboxylase (EE 4.1.1.32) and pyruvate carboxylase (EC 6.4.1.1) changed in favour of the glycolytic enzyme during pregnancy and at peak lactation, but changed in favour of the gluconeogenic enzymes immediately after parturition. 4. These changes are considered in relation to the changes in food intake and hormonal status that occur during pregnancy and lactation.
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PMID:The effects of pregnancy and lactation on the activities in rat liver of some enzymes associated with glucose metabolism. 17 Sep 98

Comparison of enzyme activities in crude extracts of methylamine-grown Pseudomonas MA (ATCC 23319) to those in succinate-grown cells indicates the involvement of an acetyl coenzyme A-independent phosphoenolpyruvate carboxylase in one-carbon metabolism. The purified phosphoenolpyruvate carboxylase is activated specifically by reduced nicotinamide adenine dinucleotide (KA = 0.2 mM). The regulatory properties of this enzyme suggests that phosphoenolpyruvate serves as a focal point for both carbon assimilation and energy metabolism.
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PMID:Reduced nicotinamide adenine dinucleotide-activated phosphoenolpyruvate carboxylase in Pseudomonas MA: potential regulation between carbon assimilation and energy production. 17 Dec 53

Administration of cadmium chloride (1.0 mg/kg s.c.) to rats, twice a day for 7 days, significantly stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose 1,6-diphosphatase and glucose 6-phosphatase, markedly increased the concentration of hepatic cyclic adenosine monophosphate and circulating blood glucose and significantly reduced serum insulin levels. Furthermore, subacute exposure to cadmium induced glucose intolerance that was associated with a decreased pancreatic secretory activity as evidenced by lowered insulinogenic indices and marked inhibition of phentolamine-stimulated insulin release. In contrast to cadmium, administration of selenium dioxide (2 X 1.0 mg/kg/day s.c., 7 days) failed to alter significantly the activities of gluconeogenic enzymes, hepatic cyclic adenosine monophosphate, blood glucose or serum insulin levels, glucose tolerance or the pancreatic secretory activity. However, administration of selenium concurrently with cadmium completely prevented the cadmium-induced increases of hepatic gluconeogenic enzymes. Treatment with selenium ameliorated the cadmium-induced hyperglycemia, hypoinsulinemia, glucose intolerance and the suppression of pancreatic secretory activity, whereas it failed to alter significantly the cadmium-induced elevation of hepatic cyclic AMP levels. Data provide evidence suggesting that subacute exposure to cadmium alters several parameters of carbohydrate metabolism and suppresses pancreatic secretory activity and that administration of selenium alone is without any appreciable effect on the above parameters. However, administration of selenium concurrently with cadmium prevents, to varying degrees, several of the cadmium-induced metabolic and functional changes.
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PMID:Protective effect of selenium on certain hepatotoxic and pancreotoxic manifestations of subacute cadmium administration. 17 75

Normal and alloxan-diabetic rats were fed ground Purina Laboratory Chow with or without 500 ppm of Aroclor 1254 (AR) ad lib for 2 weeks. In both normal and diabetic rats, AR administration decreased food consumption, weight gain and blood glucose concentration, and increased liver weight, liver:body weight ratio, total liver lipid, liver protein and malic enzyme (ME) activity. In the normal rat, AR increased the concentrations of acetoacetate and beta-hydroxybutyrate in blood, but in the diabetic rat the concentrations were markedly reduced. AR administration decreased the activity of phosphoenolpyruvate carboxykinase (PEPck) in normal liver and the activities of pyruvate carboxylase (PC), PEPck and glucose-6-phosphatase (G6Pase) in diabetic liver.
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PMID:The effects of a polychlorinated biphenyl mixture (Aroclor 1254) on liver gluconeogenic enzymes of normal and alloxan-diabetic rats. 17 2

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

This study attempted to determine whether the quantity and the quality of protein intake could influence the activity of some enzymes involved in carbohydrate metabolism. Thus, adult rats were fed for 23 days a diet containing different levels (10 to 70%) and qualities (casein, wheat gluten, and egg yolk) of protein. Variations in liver enzyme activities of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6PDH), malic enzyme (ME), glucose-6-phosphatase (G6Pase), and phosphoenolpyruvate carboxykinase (PEPCK) were studied. Also the changes in enzyme activities were compared with changes in food intake and body weight gain. Increasing the protein level produced a progressive fall in the activities of ME and PK. The decrease in PK activity was greater when the biological value of the dietary proteins was higher (P less than 0.05). On the other hand, the activities of G6PDH and PEPCK increased as the protein level increased. The activity of G6Pase was unchanged. The relationship between the two opposing enzyme activities PK and PEPCK, in relation to protein intake, shows that for each protein studied, the equilibrium between glycolysis and gluconeogenesis was obtained at different protein intakes (1.5, 1.9, and 2.2 g of protein/day/100 g of body weight, respectively, for egg yolk, casein, and wheat gluten) regardless of daily consumption of energy as carbohydrate, which are similar (8 to 9 kcal/day/100 g of body weight). This equilibrium also corresponded to the maximum weight gain (5 g) of the experimental animals. In conclusion, the experimental method used permits a simultaneous assessment of the protein and carbohydrate requirements ensuring the best weight gain in young adult rats.
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PMID:Effects of quantity and quality of dietary protein and variation in certain enzyme activities on glucose metabolism in the rat. 17 17

1. After nicotinic acid treatment, rat liver glycogen is depleted and phosphoenolpyruvate carboxykinase activity increased, to about twice the initial value. 2. The increase in phosphoenolpyruvate carboxykinase activity promoted by nicotinic acid is prevented by cycloheximide or actinomycin D, suggesting that this effect is produced by synthesis of the enzyme de novo. 3. Despite the enhancement of phosphoenolpyruvate carboxykinase activity and glycogen depletion, which occurs 5h after the injection of nicotinic acid, the gluconeogenic capacity of liver is low and considerably less than the values found in rats starved for 48h. 4. When the livers of well-fed rats are perfused in the presence of low concentrations of glucose, the activity of phosphoenolpyruvate carboxykinase significantly increases compared with the control. 5. This increase is not related to the glycogen content, but seems to be also the result of synthesis of the enzyme de novo, since this effect is counteracted by previous treatment with cycloheximide or actinomycin D. 6. Phosphoenolpyruvate carboxykinase activity is not increased in the presence of low concentrations of circulating glucose when 40 mM-imidazole (an activator of phosphodiesterase) is added to the perfusion medium. 7. Addition of dibutyryl cyclic AMP to the perfusion medium results in an increase in phosphoenolpyruvate carboxykinase activity, in spite of the presence of normal concentrations of circulating glucose. On the other hand, the concentration of cyclic AMP in the liver increases when that of glucose in the medium is low. 8. These results suggest that, in the absence of hormonal factors, the regulation of phosphoenolpyruvate carboxykinase can be accomplished by glucose itself, inadequate concentrations of it resulting in the induction of the enzyme. The mediator in this regulation, as in hormonal regulation, seems to be cyclic AMP.
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PMID:Stimulation of phosphoenolpyruvate carboxykinase (guanosine triphosphate) activity by low concentrations of circulating glucose in perfused rat liver. 17 1

Cadmium, in addition to producing a variety of toxic manifestations, is known to accumulate in certain "target" organs which include liver and kidney where histological and functional damage becomes apparent. The daily intraperitoneal injection of cadmium chloride for 21 or 45 days stimulated the activities of hepatic pyruvate carboxylase, phosphoenolpyruvate carboxykinase, fructose-1, 6-diphosphatase and glucose-6-phosphatase elevated blood glucose and urea, and lowered hepatic glycogen in rats. Whereas chronic Cd treatment failed to alter adenosine-3', 5'-monophosphate phosphodiesterase (PDE) activity, cyclic AMP (cAMY and the activity of basal and fluoride-stimulated forms of hepatic adenylate cyclase (AC) were markedly increased. However, the cAMP binding to hepatic protein kinase was decreased as was the kinase activity ration. An acute dose of Cd decreased hepatic glycogen content and increased blood glucose, serum urea, and hepatic cAMP. Chronic exposure to Cd induced adrenal hypertrophy and augmented adrenal norepinephrine and epinephrine as well as the activity of adrenal tyrosine hydroxylase. This treatment decreased prostatic and testicular weights of mature rats. Although cAMP as well as AC activity of the prostate gland were reduced, cAMP binding to the prostatic protein kinase was increased as was the activity of the cAMP-dependent form of the enzyme. Testicular AC and PDE activities, however, were stimulated, although cAMP remained unaffected. Whereas the activities of the cAMP-dependent and the independent forms of testicular protein kinase were significantly depressed, the binding of cAMP to protein kinase from testes of Cd-treated rats was not affected. In most cases, the observed metabolic alterations persisted up to 28 days on cessation of Cd administration. Subacute Cd treatment suppressed pancreatic function as evidenced by lowered serum immunoreactive insulin (IRI) in presence of hyperglycemia, as well as by partial inhibition of phentolamine-stimulated increases in serum IRI. Although chronic Cd treatment failed to alter the concentration of brain stem norepinephrine and cerebrocortical acetylcholine esterase activity, serotonin levels of brain stem were depressed and the concentration of striatal dopamine and cerebrocortical acetylcholine were significantly elevated when compared with the values seen in control nonexposed animals.
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PMID:Aspects of the biochemical toxicology of cadmium. 17 84

Since administration of mannoheptulose induces temporary hyperglycemia, the present study was conducted to elucidate this phenomenon. The results indicate that mannoheptulose stimulates the activity of hepatic fructose-1,6-diphosphatase and phosphoenolpyruvate carboxykinase, and enhances incorporation of alanine into blood glucose and hepatic glycogen. In addition, mannoheptulose increases plasma levels of glucagon and hepatic cyclic AMP concentration. Gluconeogenic effects of mannoheptulose appear to be mediated by glucagon.
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PMID:Gluconeogenic response to mannoheptulose in the rat. 17 18

The gluconeogenic capacity of mammary tissue of lactating cow was investigated by incubating mammary tissue slices with alanine, glutamate, lactate, pyruvate, or glycerol in conjunction with acetate and glucose (10mM or 1 mM). In no case was any substrate incorporated into glucose per se. In lactose synthesis, glucose was the major source of carbon although glycerol also was incorporated into lactose. Alanine, glutamate, lactate, or pyruvate were not incorporated into lactose at optimum (10 mM) or suboptimum (1 mM) concentrations of glucose. Activity of glucose-6-phosphatase was negligible in mammary tissue, less than 1% of the activity in liver or kidney tissue from the same cows. Pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and fructose-1,6-diphosphatase were in cow mammary tissue, but the activities were lower than in liver. Gluconeogenic substrates were not converted to glucose regardless of whether the incubation contained an optimum (10 mM) or a suboptimum (1 mM) glucose concentration. Consistent with the inability of cow mammary tissue to convert gluconeogenic metabolites to glucose is the virtual absence of glucose-6-phosphatase and the lack of excess gluconeogenic substrates available to the intact mammary gland of lactating cow.
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PMID:Cellular gluconeogenesis by lactating bovine mammary tissue. 17 3


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