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)

The fixation of [14C]bicarbonate into aspartate by Streptococcus lactis C10 was achieved by the combined reactions of pyruvate carboxylase (E.C. 6.4.1.1) and glutamate-oxaloacetate transaminase (E.C. 2.6.1.1). The pyruvate carboxylase from Str. lactis C10, which was most active at pH 8.0, was activated by the divalent metal ions Mn2+, Mg2+ and Co2+, and inhibited by sulphydryl reagents. The enzyme was inhibited non-competitively by aspartic acid and competitively by oxaloacetate.
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PMID:The metabolism of [14C]bicarbonate by Streptococcus lactis: the fixation of [14C]bicarbonate by pyruvate carboxylase. 71 57

Phosphoenolpyruvate (P-pyruvate) carboxylase from ripened banana fruit was purified to near homogeneity and a final specific activity of 20-23 U/mg protein; P-pyruvate carboxylase-kinase copurified with P-pyruvate carboxylase throughout the purification. Gel filtration FPLC indicated that the two proteins form a tightly associated 425-kDa complex. Both the 103-kDa and 100-kDa subunits of the P-pyruvate carboxylase alpha2beta2 hetetrotetramer were phosphorylated and subsequently dephosphorylated in vitro in a time-dependent manner when the final preparation was incubated with 0.1 mM [gamma-32P]ATP followed by rabbit muscle protein phosphatase type 2A1. Phosphoamino acid and phosphopeptide map analyses indicated that in vitro phosphorylation of both subunits likely occurs at an identical Ser residue. Maximal stoichiometry of 32P incorporation was 0.2 and 0.4 mol/mol 103-kDa and 100-kDa subunit, respectively. The level of 32P incorporation was correlated with the enzyme's activation state when assayed under suboptimal assay conditions (pH 7.3, 75 microM P-pyruvate, 0.2 mM L-malate). The main kinetic effect of phosphorylation was to decrease the enzyme's Km(P-pyruvate), as well as its sensitivity to inhibition by L-malate and L-glutamate. Banana P-pyruvate carboxylase-kinase: (a) also phosphorylated maize leaf P-pyruvate carboxylase, histone III-S, and dephosphorylated casein; (b) demonstrated Mg2+ dependence and Ca2+ independence, (c) exhibited a broad pH activity optimum of pH 8.0-8.5, and (d) was inhibited by L-malate and activated by Ba2+ and Co2+. Time-course kinetic studies suggested that P-pyruvate carboxylase exists mainly in the dephosphorylated form in preclimacteric, climacteric and postclimacteric fruit, but that its kinase is expressed throughout ripening. In situ 32P-labeling indicated that, while both subunits of ripe banana P-pyruvate carboxylase are phosphorylated in vivo, it is primarily the 100-kDa subunit that is radiolabeled. The results suggest that similar to the enzyme from leaves, root nodules and seeds, a fruit P-pyruvate carboxylase may be subject to regulatory seryl phosphorylation by an endogenous P-pyruvate carboxylase-kinase.
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PMID:Regulatory phosphorylation of banana fruit phosphoenolpyruvate carboxylase by a copurifying phosphoenolpyruvate carboxylase-kinase. 926 8

We discovered that Methanobacterium thermoautotrophicum strain DeltaH possessed pyruvate carboxylase (PYC), and this biotin prototroph required exogenously supplied biotin to exhibit detectable amounts of PYC activity. The enzyme was highly labile and was stabilized by 10% inositol in buffers to an extent that allowed purification to homogeneity and characterization. The purified enzyme was absolutely dependent on ATP, Mg2+ (or Mn2+ or Co2+), pyruvate, and bicarbonate for activity; phosphoenolpyruvate could not replace pyruvate, and acetyl-CoA was not required. The enzyme was inhibited by ADP and alpha-ketoglutarate but not by aspartate or glutamate. ATP was inhibitory at high concentrations. The enzyme, unlike other PYCs, exhibited nonlinear kinetics with respect to bicarbonate and was inhibited by excess Mg2+, Mn2+, or Co2+. The 540-kDa enzyme of A4B4 composition contained a non-biotinylated 52-kDa subunit (PYCA) and a 75-kDa biotinylated subunit (PYCB). The pycB gene was probably monocistronic and followed by a putative gene of a DNA-binding protein on the opposite strand. The pycA was about 727 kilobase pairs away from pycB on the chromosome and was probably co-transcribed with the biotin ligase gene (birA). PYCA and PYCB showed substantial sequence identities (33-62%) to, respectively, the biotin carboxylase and biotin carboxyl carrier + carboxyltransferase domains or subunits of known biotin-dependent carboxylases/decarboxylases. We discovered that PYCB and probably the equivalent domains or subunits of all biotin-dependent carboxylases harbored the serine/threonine dehydratase types of pyridoxal-phosphate attachment site. Our results and the existence of an alternative oxaloacetate synthesizing enzyme phosphoenolpyruvate carboxylase in M. thermoautotrophicum strain DeltaH (Kenealy, W. R., and Zeikus, J. G. (1982) FEMS Microbiol. Lett. 14, 7-10) raise several questions for future investigations.
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PMID:Purification, regulation, and molecular and biochemical characterization of pyruvate carboxylase from Methanobacterium thermoautotrophicum strain deltaH. 947 69

Transcarboxylase is a 1.2 million Dalton (Da) multienzyme complex from Propionibacterium shermanii that couples two carboxylation reactions, transferring CO(2)(-) from methylmalonyl-CoA to pyruvate to yield propionyl-CoA and oxaloacetate. Crystal structures of the 5S metalloenzyme subunit, which catalyzes the second carboxylation reaction, have been solved in free form and bound to its substrate pyruvate, product oxaloacetate, or inhibitor 2-ketobutyrate. The structure reveals a dimer of beta(8)alpha(8) barrels with an active site cobalt ion coordinated by a carbamylated lysine, except in the oxaloacetate complex in which the product's carboxylate group serves as a ligand instead. 5S and human pyruvate carboxylase (PC), an enzyme crucial to gluconeogenesis, catalyze similar reactions. A 5S-based homology model of the PC carboxyltransferase domain indicates a conserved mechanism and explains the molecular basis of mutations in lactic acidemia. PC disease mutations reproduced in 5S result in a similar decrease in carboxyltransferase activity and crystal structures with altered active sites.
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PMID:Transcarboxylase 5S structures: assembly and catalytic mechanism of a multienzyme complex subunit. 1532 73