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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)

1. Pyruvate carboxylase was purified to apparent homogeneity from pig liver mitochondria and shown to be free of all kinetically contaminating enzymes. 2. The enzyme has a mol. wt. of 520000 and is composed of four subunits, each with a mol. wt. of 130000. 3. The enzyme can exist as the active tetramer, dimer and monomer, although the tetramer appears to be the form in which the enzyme is normally assayed. 4. For every 520000g of the enzyme there are 4mol of biotin, 3mol of zinc and 1mol of magnesium. No significant concentrations of manganese were detected. 5. Analysis by sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicates three polypeptide chains per monomer unit, each with a mol. wt. of 47000. 6. The amino acid analysis, stoicheiometry of the reaction and the activity of the enzyme as a function of pH are also presented. 7. The enzyme is activated by a variety of univalent cations but not by Tris(+) or triethanolamine(+). 8. The activity of the enzyme is dependent on the presence of acetyl-CoA; the low rate in the absence of added acetyl-CoA is not due to an enzyme-bound acyl-CoA. The dissociation constant for enzyme-bound acetyl-CoA is a marked function of pH.
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PMID:Pig liver pyruvate carboxylase. Purification, properties and cation specificity. 444 11

The properties of pyruvate carboxylase in cultured human fibroblasts were investigated. A pH optimum around pH 7.6 was found in Tris buffer at 37 degrees C. The apparent Km for pyruvate and bicarbonate were 0.22 mmol/l and 2.1 mmol/l respectively. The activity of the crude homogenate was most stable at room temperature. The major end product was identified as citric acid during the assay conditions used. During growth the specific activity increased from 0.5 to 2 nmol/min per mg protein. The activity of pyruvate carboxylase in the crude homogenate from cultured human fibroblasts was 0.76 +/- 0.12 nmol/min per mg protein, while the activity in cultured amniotic fluid cells was 0.66 +/- 0.17 nmol/min per mg protein, suggesting the possibility of prenatal diagnosis of pyruvate carboxylase deficiency.
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PMID:Studies on pyruvate carboxylase from cultured human fibroblasts and amniotic fluid cells. 679 57

New cytochemical method, based on biochemical experiments, was elaborated for the ultrastructural localization of phospho(enol)pyruvate carboxylase (EC 4.1.1.31). The procedure was used to study the saprophytic submerged mycelium of the ascomycetous fungus Claviceps purpurea Tul. producing clavine alkaloids. The pelleted mycelium was fixed in ice cold 3% glutaraldehyde in 50 mM cacodylate buffer pH 7.2 and washed repeatedly in the same cold buffer The reaction mixture contained 100 mM Tris-HCl buffer pH 9.0, 10 mM phospho(enol)pyruvate, 30 mM sodium potassium tartrate, 3 mM Pb(NO3)2, 60 mM MgCl2 and 30 mM NaHCO3. Enzyme activity was localized in vacuoles, particularly inside lipid globules (spherosomes) and less frequently in membranous vesicles. Acetyl-CoA activated PEP-carboxylase both in cell free extracts and in the cytochemical staining. Aspartate inhibited the enzyme in the biochemical assay with coupled malate dehydrogenase system; the cytochemical reaction was not influenced, probably due to the interference of asparagine synthase (EC 6.3.1.1).
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PMID:Electron-cytochemical localization of phospho(enol)pyruvate carboxylase (EC 4.1.1.31) in fungal cells. 739 80