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. Naturally-occurring and synthetic analogues of phenylalanine, tyrosine, histidine, arginine, proline, tryptophan and the sulphur amino acids have beeen tested in rat reticulocytes and in the Reuber H35 hepatoma for effects on protein synthesis and protein degradation and on the heat lability of phosphoenolpyruvate carboxykinase (EC 4.1.1.32) in the hepatoma cells. The experiments were designed to test whether the analogues could be incorporated into mammalian proteins and whether the resultant proteins would be degraded at an accelerated rate. 2. Several analogues, including thiazolylanine, triazolalanine and selenocystine both stimulated protein synthesis and produced labile protein in reticulocytes. Other analogues, such as dihydroxyphenylalanine, thioproline and pipecolic acid accelerated protein breakdown but probably indirectly via an inhibition of protein synthesis. Azetidine-2-carboxylic acid had the largest effect on protein breakdown in reticulocytes. 3. Labile protein was produced in hepatoma cells incubated in the presence of azetidine-2-carboxylic acid, canavanine, indospicine, triazolalanine, 2-, 3- and 4-fluorophenylalanine. These same analogues, together with 3,4-dehydroproline, beta-2-thienylalanine, dihydroxyphenylalanine, histidinol, 5- and 6-fluorotryptophan, selenocystine and selenomethionine produced heat-labile phosphoenolpyruvate carboxykinase. Enzyme induced in the presence of selenomethionine or indospicine showed the largest increases in heat lability, and for these analogues equimolar concentrations of methionine and arginine respectively were needed to nullify the enzyme abnormality. 4. The toxicity of the same naturally-occurring analogues has been discussed in terms of their ability to be incorporated into cell proteins.
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PMID:Effects of amino acid analogues on protein synthesis and degradation in isolated cells. 21 95

Phosphoenolpyruvate carboxykinase (GTP) [GTP;oxaloacetate carboxy-lyase(transphosphorylating); EC 4.1.1.32] is absent in rat liver cytosol during fetal life and is synthesized initially at birth. De novo synthesis of the enzyme can be induced prematurely by injection of dibutyryl cyclic AMP or glucagon into fetal animals in utero. In this study a wheat germ translation assay was used to quantitate the level of total functional mRNA for phosphoenolpyruvate carboxykinase in the liver of fetal rats at 21 days of pregnancy under different induction situations. The translatable mRNA for the enzyme was marginally detectable in fetal rat liver. Administration of either glucagon or dibutyryl cyclic AMP to fetal rats in utero caused a marked induction of functional mRNA for this enzyme. Three hours after administration of dibutyryl cyclic AMP, the level of translatable mRNA increased almost 23-fold, but by 6 hr the level dropped approximately 60%. Administration of actinomycin D prior to dibutyryl cyclic AMP in 21-day fetal rats prevented the appearance of newly synthesized poly(A)-containing RNA in the cytoplasm as well as the induction of translatable mRNA for phosphoenolpyruvate carboxykinase. In animals delivered prematurely and maintained for varying periods, the translatable mRNA for the enzyme accumulated in the liver at a rate comparable to that observed for enzyme synthesis.
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PMID:Changes in hepatic messenger RNA for phosphoenolpyruvate carboxykinase (GTP) during development. 21 40

The mRNA coding for the gluconeogenic enzyme phosphoenolpyruvate carboxykinase (GTP) (EC 4.1.1.32) was partially purified from the liver of cyclic-AMP-treated rats by a procedure involving multiple oligo(dT)-cellulose chromatographies and sucrose gradient fractionations. The purification was monitored by translational assay using a wheat germ extract. Relative to RNA bound once to oligo(dT)-cellulose, the final material was enriched 20-fold in template activity for phosphoenolpyruvate carboxykinase synthesis. With this RNA preparation, cell-free enzyme synthesis amounted to 5% of total mRNA-directed protein synthesis. The apparent sedimentation coefficient of phosphoenolpyruvate carboxykinase mRNA in sucrose gradients was between 20 and 22 S, corresponding to an average molecular weight of 0.93 X 10(6). By formamide/polyacrylamide gel electrophoresis the molecular weight of the enzyme mRNA was estimated at between 0.91 X 10(6) and 1.12 X 10(6). From these estimates, it was concluded that considerable non-coding sequence(s) are present in the mRNA. Approximately 20% of the enzyme mRNA in rat liver failed to bind to oligo(dT)-cellulose, presumably because of the absence of a poly(A) segment. The translation of phosphoenolpyruvate carboxykinase mRNA by the wheat germ extract was inhibited in the presence of 7-methylguanosine 5'-phosphate. The enzyme mRNA appears therefore to have a 'cap' at the 5' end.
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PMID:Partial purification and characterization of rat-liver messenger RNA coding for phosphoenolpyruvate carboxykinase (GTP). 21 68

1. Comparison of the maximum activities of pyruvate kinase with those of phosphofructokinase in a large number of muscles from invertebrates and vertebrates indicates that, in general, in any individual muscle, the activity of pyruvate kinase is only severalfold higher than that of phosphofructokinase. This is consistent with the suggestion, based on mass-action ratio data, that the pyruvate kinase reaction is non-equilibrium in muscle. However, the range of activities of pyruvate kinase in these muscles is considerably larger than that of phosphofructokinase. This difference almost disappears if the enzyme activities from muscles that are known to possess an anaerobic ;succinate pathway' are excluded. It is suggested that, in these muscles, phosphofructokinase provides glycolytic residues for both pyruvate kinase (i.e. glycolysis) and phosphoenolpyruvate carboxykinase (i.e. the succinate pathway). This is supported by a negative correlation between the activity ratio, pyruvate kinase/phosphofructokinase, and the activities of nucleoside diphosphokinase in these muscles, since high activities of nucleoside diphosphokinase are considered to indicate the presence of the succinate pathway. 2. The effect of fructose bisphosphate on the activities of pyruvate kinase from many different muscles was studied. The stimulatory effect of fructose bisphosphate appears to be lost whenever an efficient system for supply of oxygen to the muscles is developed (e.g. insects, squids, birds and mammals). This suggests that activation of pyruvate kinase is important in the co-ordinated regulation of glycolysis in anaerobic or hypoxic conditions, when the change in glycolytic flux during the transition from rest to activity needs to be large in order to provide sufficient energy for the contractile activity. However, lack of this effect in the anaerobic muscles of the birds and mammals suggests that another metabolic control may exist for avian and mammalian pyruvate kinase in these muscles.
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PMID:Maximum activities and effects of fructose bisphosphate on pyruvate kinase from muscles of vertebrates and invertebrates in relation to the control of glycolysis. 21 27

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

Mitochondria of cultured normal human fibroblast cells were found to contain the enzyme phosphoenolpyruvate carboxykinase. The activity of this enzyme in these cells is increased 2- to 3-fold by addition of 5 . 10(-4) M dibutyryl cyclic AMP, or 1.5- to 2-fold by the addition of dexamethasone (2 . 10(-7) M) or hydrocortisone (1.38 . 10(-6) M). These increases in enzyme activity were inhibited cycloheximide and actinomycin D, suggesting they are dependent upon de novo protein synthesis. Cultured human fibroblasts may thus provide a useful system for studying the regulation of mitochondrial phosphoenolpyruvate carboxykinase.
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PMID:Induction of mitochondrial phosphoenolpyruvate carboxykinase in cultured human fibroblasts. 21 92

Starvation or feeding rats on a high-protein diet, valine or isoleucine, but not leucine, increases the activity of muscle phosphoenolpyruvate carboxykinase, but has no effect on NADP+-linked malate dehydrogenase. This suggests that muscle phosphoenolpyruvate carboxykinase is involved in oxidation or conversion of some amino acids to alanine.
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PMID:The role of phosphoenolpyruvate carboxykinase in amino acid metabolism in muscle. 21 68

Xenopus laevis (Daudin) adult specimens were submitted to hypophysectomy. Although the operation resulted subtotal, it served the purpose of removing the prolactin-producing cells, whereby the involvement of endogenous prolactin in osmoregulation phenomena was excluded. In the operated animals treated with ovine prolactin the following metabolic parameters, which are closely dependent upon interrenal activity, were estimated: 1) intestine alkaline phosphomonoesterase activity (E.C. 3.1.3.1); 2) liver glycogen level; 3) glucose-6-phosphatase (E.C. 3.1.3.9.) and phosphoenolpyruvate carboxykinase (E.C. 4.1.1.32.) in the liver; 4) blood glucose level; 5) blood ammonia and urea levels; 6) carbamoylphosphate synthetase activity in the liver (E.C. 2.7.2.a); 7) muscle sodium and potassium levels. The above metabolic parameters were found to be pressed by subtotal hypophysectomy and after subsequent prolactin treatment showed the tendency to go back to values similar to those of control animals.
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PMID:Biochemical data on subtotally hypophysectomized Xenopus laevis (Daudin) adult specimens treated or not with prolactin. 21 25

The effects of triamcinolone on renal and hepatic phosphoenolpyruvate carboxykinase activity in the developing rat were investigated. The hormone induced increases in pre-existing enzyme activity of both tissues in fetal and neonatal rats, yet did not cause the primary appearance of phosphoenolpyruvate carboxykinase activity in utero. Neonatal hepatic phosphoenolpyruvate carboxykinase activity was increased 2--3 fold by triamcinolone form the 3rd to the 15th postnatal day. This was shown to be additive to the effect of Bt2cAMP on enzyme activity. The increases in phosphoenolpyruvate carboxykinase activity were demonstrated to be due to increased synthesis of the enzyme, which was accompanied by a proportionate increase in the amount of functional phosphoenolpyruvate carboxykinase mRNA, as measured by the polyribosomal and poly(A)-containing RNA directed cell-free synthesis of the enzyme. The demonstration of a triamcinolone effect on kidney and liver phosphoenolpyruvate carboxykinase activity in fetal and neonatal rats provides support for a possible role of glucocorticoids in the regulation of phosphoenolpyruvate carboxykinase activity during development.
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PMID:Effect of triamcinolone on renal and hepatic phosphoenolpyruvate carboxykinase in the newborn rat. Changes in the rate of synthesis of the enzyme and in the activity of its translatable messenger RNA. 21 21

A child with lactic acidosis, severe mental and developmental retardation, and proximal renal tubular acidosis is presented. Biopsy and autopsy studies show severe hepatic, renal cortical, and cerebral deficiencies in pyruvate carboxylase (EC 6.4.1.1) activity. The patient had 1.81 +/- 0.20 units/g fresh weight at biopsy and 0.75 +/- 0.07 units/g fresh weight hepatic pyruvate carboxylase activity at autopsy compared with 10.9, 11.3, and 9.5 units/g fresh weight in two autopsy and one biopsy controls, respectively. The patient's renal cortical pyruvate carboxylase activity at autopsy was 0.008 +/- 0.004 units/g fresh weight compared with 5.05 units/g in the autopsy control. The patient had no detectable (less than 0.018 units/g fresh weight) cerebral pyruvate carboxylase activity at autopsy compared with 0.44, 0.53, and 0.695 units/g in the autopsy cerebrum of one human and two rhesus monkeys, respectively. Pyruvate dehydrogenase complex, phosphoenolpyruvate carboxykinase (PEPCK, EC 4.1.1.32), and fructose-1,6-bisphosphatase (EC 3.1.3.11) activities were in the normal range. The patient's urine pH was above 7.9 when the total serum CO2 was greater than 7.8 mM. However, the patient was able to acidify the urine to pH 5.1 when the total serum CO2 was 1.6 mM. The neuropathologic examination of the brain at autopsy revealed no sign of Leigh's disease, although developmental and degenerative lesions were observed. This is the first reported patient with a primary deficiency in hepatic, renal, and cerebral pyruvate carboxylase deficiency in whom the neuropathologic lesions, distinct from those of Leigh's disease, and proximal renal tubular acidosis have both been documented.
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PMID:Pyruvate carboxylase deficiency and lactic acidosis in a retarded child without Leigh's disease. 21 11


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