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:6.4.1.1 (pyruvate carboxylase)
1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have synthesized S-acetonyl-CoA from CoASH and 1-bromoacetone. This thioether-containing structural analogue of acetyl-CoA is a potent competitive inhibitor, with respect to acetyl-CoA, of citrate synthase, phosphotransacetylase, and carnitine acetyltransferase. This analog will not activate Escherichia coli phosphoenolpyruvate carboxylase or rat liver pyruvate carboxylase, two enzymes which require acetyl-CoA as an obligate activator. Furthermore, acetonyl-CoA will not compete with acetyl-CoA for binding to these enzymes showing the apparent absolute requirement of these two enzymes for a thioester group on the activating ligand. S-Acetonyl-CoA should be a useful reagent in the investigation of acetyl-CoA-requiring processes.
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PMID:S-acetonyl-CoA. A nonreactive analog of acetyl-CoA. 699 55

The kinetics of nucleotide binding to pyruvate carboxylase have been studied by measuring the fluorescence changes that occur on the binding and release of FTP and FDP, which are fluorescent formycin analogues of ATP and ADP. The rate constants and equilibrium binding constants for both MgFTP and MgFDP binding to pyruvate carboxylase have been determined. From the kinetics of displacement of MgFTP by MgATP and binding of MgFTP in the presence of MgATP, the rate constants of MgATP binding were estimated. A slow component to the fluorescence changes was seen to occur after the initial rapid, bimolecular binding step, when formycin nucleotides were mixed with the enzyme. HCO3- and pyruvate were shown to quench the fluorescence of enzyme-bound MgFTP, but did not affect the affinity of the enzyme for the nucleotide. Acetyl CoA reduced the affinity of the enzyme for both MgFDP and MgFTP by about 3-fold by decreasing the association rate constants (by 25%) and increasing the dissociation rate constants (by 2-fold). In the absence of Mg2+ a very rapid component to FTP binding was observed that was complete within about 3 ms, but no fast component was observed comparable to that seen in the presence of 4.5 mM MgCl2. Increasing the [Mg2+] gradually abolished this very fast component of the binding, while the amplitude of the fast component increased, although the rate constant for this component did not appear to be strongly dependent on [Mg2+]. The rate constants of the slow component of Mg.formycin nucleotide binding did not appear to be dependent on nucleotide concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Kinetics of nucleotide binding to pyruvate carboxylase. 754 19

Setaria digitata, a cattle filarial parasite, similar to human filarial parasites, possesses significant activities of the 4 transhydrogenases namely NADH-NAD+, NADPH-NAD+, NADH-NADP+, and NADPH-NADP+ in the sonicated mitochondria like particles. The transhydrogenases appear to regulate the metabolic pathways of the parasite in response to the presence of adenyl nucleotides and are non-energy linked. Observations on the transhydrogenase and fumarate reductase activities show the existence of a protein bound NAD in the MLP and a linkage between the fumarate reductase system and malic enzyme through transhydrogenases. The malate dismutation reaction is the result of malic and fumarase enzyme activities. Fumarase and fumarate reductase activities result in succinate formation under anaerobic conditions showing major energy production at the fumarate reductase site. The existence of acetate kinase, phosphotransacetylase, pyruvate carboxylase, propionyl CoA carboxylase and CoA transferase enzymes in the mitochondrial system shows the presence of other energy producing sites in the parasite. The transhydrogenase system, NAD+/NADP+ malic enzyme, fumarase and fumarate reductase are the key enzymes of, production of reducing power for synthetic reactions and regulation of oxidative and reductive stages of the mitochondrial system. Hence, specific drugs targeted against this interconnected complex enzyme system, will be very effective in the control of filarial parasites.
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PMID:Transhydrogenase activities and malate dismutation linked to fumarate reductase system in the filarial parasite Setaria digitata. 755 63

Pyruvate carboxylase (PC) was purified to homogeneity from an overexpressing strain of the purple photosynthetic bacterium Rhodobacter capsulatus using a rapid dye-ligand affinity chromatography procedure, in which dye-bound enzyme was specifically eluted with a low concentration of acetyl-CoA, an allosteric activator of the enzyme. The enzyme purified by this method was obtained in 75% yield with a specific activity of 40 U (mg protein)-1. In contrast, affinity chromatography on a monomeric avidin column, commonly used in the purification of biotin-containing carboxylases, resulted in a yield of < 40%, with a specific activity of 10 U (mg protein)-1. The enzyme purified by the dye-linked procedure had a subunit molecular mass of 140,000 Da and was absolutely dependent on acetyl-CoA for activity. Acetyl-CoA was also effective in protecting the enzyme from thermal denaturation. The enzyme was inhibited by 2-oxoglutarate and, to a lesser extent, L-aspartate, with sigmoidal kinetics with respect to acetyl-CoA concentration. The amino acid composition, pH optimum and kinetic constants for pyruvate, ATP and bicarbonate were determined. An N-terminal sequence of 26 residues was obtained, which was homologous to the N-terminal regions of several eukaryotic PCs, propionyl-CoA carboxylases and acetyl-CoA carboxylase.
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PMID:Acetyl-CoA-dependent pyruvate carboxylase from the photosynthetic bacterium Rhodobacter capsulatus: rapid and efficient purification using dye-ligand affinity chromatography. 758 22

Pyruvate carboxylase plays an important role in intermediary metabolism, catalysing the formation of oxaloacetate from pyruvate and HCO3-, with concomitant ATP cleavage. It thus provides oxaloacetate for gluconeogenesis and replenishing tricarboxylic acid cycle intermediates for fatty acid, amino acid and neurotransmitter synthesis. The enzyme is highly conserved and is found in a great variety of organisms including fungi, bacteria and plants as well as higher organisms. It is a member of a group of biotin-dependent enzymes and the biotin prosthetic group is covalently bound to the polypeptide chain of the enzyme, there normally being four such chains in the native, tetrameric enzyme. The overall reaction catalysed by pyruvate carboxylase involves two partial reactions that occur at spatially separate subsites within the active site, with the covalently bound biotin acting as a mobile carboxyl group carrier. In the first partial reaction, biotin is carboxylated using ATP and HCO3- as substrates whilst in the second partial reaction, the carboxyl group from carboxybiotin is transferred to pyruvate. The chemical mechanisms of the partial reactions and some of the roles played by amino acid residues of the enzyme in catalysing the reaction have been elucidated. The domain structure of the yeast enzyme has been deduced by comparing its amino acid sequence with those of enzymes that have similar catalytic functions. The quaternary structures of the pyruvate carboxylases studied so far, all involve a tetrahedron-like arrangement of the subunits. The major regulator of enzyme activity, acetyl CoA, stimulates the cleavage of ATP in the first partial reaction and in addition it has been shown to induce a conformational change in the tetrameric structure of the enzyme. In the past, the lack of any detailed structural information on the enzyme has hampered efforts to fully understand how this and other biotin-dependent enzymes function and are regulated. With the recent cloning of the enzyme from a variety of sources and the performance of three-dimensional structural studies, the next few years should see much progress in our understanding the mechanism of action of this enzyme.
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PMID:The structure and the mechanism of action of pyruvate carboxylase. 778 Aug 27

We studied the effect of a supplement of biotin (10 mg/d) or a placebo under double-blind conditions on plasma biotin concentrations and lymphocyte propionyl CoA carboxylase (PCC) and pyruvate carboxylase (PC) in 22 children with severe protein-energy malnutrition (PEM) (5 with kwashiorkor, 10 with marasmus, and 7 "sugar babies"). There were significant differences between the malnourished and control subjects only for PCC, although not among the three PEM types. Six of the patients had both PC and PCC activities below the lowest of the normal control subjects; there was no correlation between biotin concentrations and carboxylase activities in individual patients. In response to biotin supplementation, the greatest change in lymphocyte carboxylase activities was detected in patients who had abnormally decreased initial carboxylase activities, but the response was not related to initial plasma biotin concentration. These results indicate that these enzyme deficiencies are the result of a nutritionally determined biotin deficiency, that carboxylases and especially PCC are better indicators of the biotin status in individual patients than is the plasma biotin concentration, and that in some malnourished patients biotin deficiency may be rate-limiting in their nutritional homeostasis.
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PMID:Biotin supplementation affects lymphocyte carboxylases and plasma biotin in severe protein-energy malnutrition. 784 79

The mitochondrial pyruvate carboxylase catalyses the ATP-dependent carboxylation of pyruvate to oxaloacetate. Since pyruvate carboxylase generates oxaloacetate for Krebs cycle function, it is proposed that the enzyme activity may be enhanced by exercise. To investigate this proposition, pyruvate carboxylase activity was determined in the heart, soleus and gastrocnemius (white portion) muscles of sedentary and swimming-trained adult rats (1 hour per day, 5 days a week, during 5 weeks) under the following conditions: rest, one hour of exercise and exhaustion. The results show that the pyruvate carboxylase activity is increased during exercise in both the sedentary and trained groups of rats. The stimulatory mechanism is unknown but it is possibly related to the generation of pyruvate from the breakdown of glycogen and acetyl CoA during fatty acid oxidation.
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PMID:Pyruvate carboxylase activity in the heart and skeletal muscles of the rat. Evidence for a stimulating effect of exercise. 803 15

The quantities of biotinyl proteins in liver of young rats were compared with age-matched controls at intervals during depletion and repletion of biotin. Growth rate and the concentrations of biotinyl proteins previously proposed as mitochondrial storage forms of acetyl CoA carboxylase rapidly decreased in response to biotin deprivation, whereas neither the concentration nor activity of cytosolic acetyl CoA carboxylase was affected. Concentrations of carboxylases active within mitochondria (pyruvate carboxylase, propionyl CoA carboxylase and 3-methyl crotonyl CoA carboxylase) decreased only after d 28. When biotin was injected into biotin-deficient rats, concentrations of the carboxylases active within mitochondria were restored to control levels within 3 h, whereas the concentrations of putative mitochondrial storage forms of acetyl CoA carboxylase reached normal levels only after 9 h, indicating that the injected biotin was preferentially used for the synthesis of the carboxylases active within mitochondria rather than acetyl CoA carboxylase. Mitochondrial acetyl CoA carboxylase may serve as a reservoir to maintain a normal concentration of cytosolic acetyl CoA carboxylase in liver of rats deprived of biotin and provide biotin, indirectly, to maintain essentially normal concentrations of the biotinyl enzymes active within mitochondria for several weeks after rats were fed a biotin-deficient diet.
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PMID:Depletion and repletion of biotinyl enzymes in liver of biotin-deficient rats: evidence of a biotin storage system. 809 68

The fate of [3-13C]alanine administered to last instar larvae of an insect Manduca sexta was investigated in vivo by 13C-NMR spectroscopy. Following injection of the isotopically substituted substrate and conversion to [3-13C]pyruvate 13C was principally incorporated into C2, C3 and C4 of glutamate and glutamine in unparasitized ad libitum-fed larvae, insects starved 48 hr prior to injection and larvae parasitized by the insect parasite Cotesia congregata. Selective labeling at C2 and C3 of glutamate/glutamine resulted from carboxylation of [3-13C]pyruvate to [2,3-13C]oxaloacetate catalyzed by pyruvate carboxylase, randomization of the label in fumarate, and synthesis of glutamate and glutamine after condensation with acetyl CoA to [2 proR,3-13C]citrate. In contrast, enrichment at C4 of glutamate and glutamine resulted from oxidation [3-13C]pyruvate to [2-13C]acetyl CoA catalyzed by pyruvate dehydrogenase followed by condensation with oxaloacetate. The ratio of enrichment (C2 + C3): C4 provided a measure of the relative contributions of the pyruvate dehydrogenase and pyruvate carboxylase catalyzed pathways of substrate utilization by the tricarboxylic acid cycle. The mean ratio was 0.6 and 0.7 in control and parasitized larvae, respectively, and 2.4 in starved insects. The latter result demonstrated that substrate utilization by the TCA cycle was markedly altered by starvation. In addition, the rate of labeled alanine metabolism was significantly reduced by starvation. The concentrations of glutamate and glutamine in the blood (hemolymph) were similar in all three groups of insects. No evidence for gluconeogenesis was observed in any group. Starved larvae incorporated label into C6 of glucose and trehalose but no complementary enrichment at C1 was observed. This result was consistent with the activity of the non-oxidative phase of the pentose phosphate pathway during which labeled glyceraldehyde-3-phosphate arising from [3-13C]alanine reacts with sedoheptulose-7-phosphate yielding erythrose-4-phosphate and [6-13C]fructose-6-phosphate catalyzed by transaldolase. Specifically labeled fructose-6-phosphate then gives rise to glucose and trehalose labeled at C6. Preliminary analysis of the hemolymph of starved insects indicated the presence of several hexose phosphates labeled at C6. The hemolymph level of trehalose was significantly reduced in both starved and parasitized insects. Lipogenesis from [3-13C]alanine was evident in unparasitized control larvae but was absent in parasitized and starved insects. The pattern of labeling in fatty acid was consistent with de novo pathway utilizing [2-13C]acetyl CoA derived by oxidation of [3-13C]alanine.
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PMID:Metabolic fate of alanine in an insect Manduca sexta: effects of starvation and parasitism. 810 Jul 13

We present a new case of holocarboxylase synthetase (HCS) deficiency, a rare autosomal recessive metabolic disorder, causing the "early-onset" form of multiple carboxylase deficiency. The patient was born at term of healthy consanguineous parents after an uncomplicated pregnancy. On the 2nd day of life she refused oral feeding, became tachydyspnoeic and showed excessive weight loss. Laboratory studies showed metabolic acidosis, marked lactic acidaemia, hyperammonaemia and increased urinary excretion of 3-hydroxyisovaleric acid, 3-methylcrotonylglycine, 3-hydroxpropionic acid and methylcitric acid. Peritoneal dialysis combined with oral supplementation of biotin (10 mg/day) started on the 3rd day of life resulted in rapid clinical recovery and normalisation of biochemical parameters. HCS deficiency was established in lymphocytes and skin fibroblasts. The activities of all biotin-dependent carboxylases were severely decreased in fibroblasts grown in medium with moderate biotin concentration (10(-8) mol/l) but normal in a high biotin medium (10(-5) mol/l). Mitochondrial carboxylase activities in lymphocytes were 23%-29% of mean normal during therapy with 20 mg of biotin/day, with the higher dose of 40 mg/day they were within (3-methylcrotoryl-CoA carboxylase, pyruvate carboxylase) or slightly below (propionyl-CoA carboxylase) the normal range. At the age of 3 years the patient's physical and psychomotor development are normal. Early biotin supplementation should be considered in newborns with lactic acidosis and organoaciduria until a final diagnosis has been established. Furthermore, the required individual dose of biotin has to be carefully evaluated biochemically for the individual patient.
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PMID:Holocarboxylase synthetase deficiency: early diagnosis and management of a new case. 831 16


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