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. 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

Catecholamines induced an increase in the activity of rat adipose tissue and liver phosphopyruvate carboxylases that was maintained for 48h. The response of adipose tissue phosphopyruvate carboxylase was blocked by actinomycin D, corticosteroids and propranolol, whereas corticosteroids and propranolol did not affect the liver enzyme. Cortisol phosphate, like actinomycin D, interfered only with the initiation of the increase in enzyme activity caused by noradrenaline, but not with the process of enzyme accumulation. In contrast, cycloheximide was effective in blocking enzyme induction throughout the course of the catecholamine effect. Adrenocorticotrophic hormone caused a short-term induction of adipose tissue phosphopyruvate carboxylase, which could be blocked by propranolol. Hepatic phosphopyruvate carboxylase, but not the adipose tissue enzyme, was induced by dibutyryladenosine 3':5'-cyclic monophosphate and by glucagon. Both nicotinic acid and nicotinamide decreased the normal induction of adipose tissue phosphopyruvate carboxylase caused by starvation, but only nicotinamide increased the activity of the liver enzyme.
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PMID:The interaction of catecholamines and adrenal corticosteroids in the induction of phosphopyruvate carboxylase in rat liver and adipose tissue. 434 97

Two auxotrophic mutants (SM16 and SM51) of Salmonella typhimurium, which for aerobic growth, with hexoses as carbon source, required lysine and methionine (SM51 required also nicotinic acid), were isolated and characterized. The requirement for the amino acids disappeared in anaerobiosis. Neither lipoate nor 4-hydroxybenzoate was effective in supporting aerobic growth of the mutants. The lysine and methionine requirement for aerobic growth was due to the absence in the mutants of the enzymatic activities of the alpha-ketoglutarate dehydrogenase complex. The mutants could not use succinate as carbon source even after enrichment of the growth medium with acid-hydrolyzed casein and yeast extract. No phosphoenolpyruvate carboxykinase activity was found in the mutants, a phenomenon which explained their inability to use succinate. By interrupted conjugation and by transduction experiments, the positions of the three affected loci, pck, suc, and Nic, were located at approximately 17 to 19 min of the S. typhimurium chromosome; they were found to be closely linked. From different criteria, it appears as if the genetic lesions present in both mutants are due to deletion of a small chromosome fragment.
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PMID:Mutants of Salmonella typhimurium lacking phosphoenolpyruvate carboxykinase and alpha-ketoglutarate dehydrogenase activities. 491 43

Male weanling rats were meal-fed (2 hours daily) on a vitamin B-6-deficient diet for 8 weeks; the controls were pair-fed. Vitamin B-6 deficiency led to the expected decreases in the activities of hepatic alanine and aspartate aminotransferases but did not influence those of glutamate dehydrogenase (EC 1.4.1.2), pyruvate carboxylase (EC 6.6.1.1), phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and pyruvate kinase (EC 2.7.1.40). The ability of the deficient rats to incorporate 14C from labeled alanine into blood glucose and expired CO2 was diminished, but pyruvate-U-14C was utilized normally. The deficiency did not influence gluconeogenesis from glutamate or 2-oxoglutarate. Furthermore, the gluconeogenic potential of renal cortex slices incubated with pyruvate or 2-oxoglutarate was unaltered by the deficiency. These data suggest that the impairment of gluconeogenesis from amino acids in vitamin B-6 deficiency may be the consequence of diminished transamination prior to oxidative deamination.
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PMID:Gluconeogenesis in meal-fed, vitamin B-6-deficient rats. 735 97

3-Mercaptopicolinae (3-MP) blocks gluconeogenesis from lactate, pyruvate, alanine, and other substrates through its inhibition of phosphoenolpyruvate carboxykinase. Nevertheless, we observed increased glycogenesis, net glucose uptake, and glucose-6-P levels in livers perfused with glucose in the presence of 3-MP. In perfusions with 20 mM dihydroxyacetone, increased glycogenesis and decreased glucose production were observed with 3-MP. These metabolic effects suggested additional site(s) of action of 3-MP. Further studies showed that 3-MP inhibits glucose-6-P phosphohydrolase activity of intact liver microsomes. Several compounds with structural similarities to 3-MP (2-mercaptonicotinic acid, picolinic acid, cysteine, reduced glutathione, nicotinic acid, quinolinic acid, tryptophan, and pyridine) were tested for their effect on glucose-6-P phosphohydrolase activity. Two of these compounds, 2-mercaptonicotinic acid and picolinic acid, were found to inhibit. In perfusions including 7.5 mM fructose, the addition of 3-MP, 2-mercaptonicotinic acid, or picolinic acid increased glycogenesis, decreased glucose production, and increased hepatic glucose-6-P concentrations. These observations indicate that the inhibition of glucose-6-P phosphohydrolase may play a role in enhanced glycogenesis from glucose, dihydroxyacetone, and fructose in isolated livers from 48-h fasted rats perfused with 3-MP or certain sulfhydryl-containing and sulfhydryl-devoid analogs.
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PMID:Inhibition of glucose-6-phosphate phosphohydrolase by 3-mercaptopicolinate and two analogs is metabolically directive. 839 68

Although it was proved that peroxovanadate-nicotinic acid (POV) can decrease hyperglycaemia and hyperlipaemia, its molecular biochemical mechanism of action is unclear. The present investigation aimed at studying the effect of POV on gene expression and enzymatic activity of hepatic phosphoenolpyruvate carboxykinase (PEPCK) and blood lipid metabolism in streptozotocin-diabetic rats in order to suggest the molecular biochemical mechanism of POV action in lowering hyperglycaemia and hyperlipaemia. The results showed that the gene expression and enzymatic activity of hepatic cytosolic PEPCK, which were increased in diabetic rats, were significantly reduced following POV treatment. Similarly, POV was shown to oppose significantly the hyperglycaemia and hyperlipaemia in these diabetic rats. These results suggested that a possible mechanism of POV action was to inhibit PEPCK gene expression as well as PEPCK activity which could explain the reduced gluconeogenesis and hyperglycaemia.
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PMID:Effect of peroxovanadate compound on phosphoenolpyruvate carboxykinase gene expression and lipid metabolism in diabetic rats. 940 71