Publications

• Pyruvate kinase from Chlamydia trachomatis is activated by fructose-2,6-bisphosphate.

  Iliffe-Lee E.R., McClarty G.

  Pyruvate kinase is the final regulatory point in the catabolic Embden-Meyerhoff-Parnas pathway, which controls the carbon flux of glycolytic intermediates and regulates the level of ATP in the cell. In a previous study, we identified, cloned and sequenced pyruvate kinase from the obligate intracel ... >> More

  Pyruvate kinase is the final regulatory point in the catabolic Embden-Meyerhoff-Parnas pathway, which controls the carbon flux of glycolytic intermediates and regulates the level of ATP in the cell. In a previous study, we identified, cloned and sequenced pyruvate kinase from the obligate intracellular bacterium Chlamydia trachomatis and demonstrated that the enzyme was active in crude extract. Here, we report the kinetic properties of highly purified C. trachomatis pyruvate kinase. The results indicate that C. trachomatis pyruvate kinase is 53.5 kDa with a pH optima of 7.3. Kinetic studies show that C. trachomatis pyruvate kinase requires both K+ and Mg2+ ions for activity, exhibits sigmoidal kinetics with respect to phosphoenolpyruvate and Michaelis-Menten kinetics with respect to ADP. In addition, C. trachomatis pyruvate kinase is able to use alternative nucleoside diphosphates as phosphate acceptors, although it shows the greatest activity with ADP. In contrast to other bacterial pyruvate kinases that are activated by AMP, our data show that AMP, in addition to ATP and GTP, inhibits C. trachomatis pyruvate kinase. Surprisingly, unlike any other known bacterial pyruvate kinase, C. trachomatis pyruvate kinase was allosterically activated by fructose-2,6-bisphosphate, an important regulatory metabolite that has only been reported in eukaryotes. << Less

  Mol Microbiol 44:819-828(2002) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Purification and characterization of cytosolic pyruvate kinase from banana fruit.

  Turner W.L., Plaxton W.C.

  Cytosolic pyruvate kinase (PK(c)) from ripened banana (Musa cavendishii L.) fruits has been purified 543-fold to electrophoretic homogeneity and a final specific activity of 59.7 micromol of pyruvate produced/min per mg of protein. SDS/PAGE and gel-filtration FPLC of the final preparation indicate ... >> More

  Cytosolic pyruvate kinase (PK(c)) from ripened banana (Musa cavendishii L.) fruits has been purified 543-fold to electrophoretic homogeneity and a final specific activity of 59.7 micromol of pyruvate produced/min per mg of protein. SDS/PAGE and gel-filtration FPLC of the final preparation indicated that this enzyme exists as a 240 kDa homotetramer composed of subunits of 57 kDa. Although the enzyme displayed a pH optimum of 6.9, optimal efficiency in substrate utilization [in terms of V(max)/K(m) for phosphoenolpyruvate (PEP) or ADP] was equivalent at pH 6.9 and 7.5. PK(c) activity was absolutely dependent upon the presence of a bivalent and a univalent cation, with Mg(2+) and K(+) respectively fulfilling this requirement. Hyperbolic saturation kinetics were observed for the binding of PEP, ADP, Mg(2+) and K(+) (K(m) values of 0.098, 0.12, 0.27 and 0.91 mM respectively). Although the enzyme utilized UDP, IDP, GDP and CDP as alternative nucleotides, ADP was the preferred substrate. L-Glutamate and MgATP were the most effective inhibitors, whereas L-aspartate functioned as an activator by reversing the inhibition of PK(c) by L-glutamate. The allosteric features of banana PK(c) are compared with those of banana PEP carboxylase [Law and Plaxton (1995) Biochem. J. 307, 807-816]. A model is presented which highlights the roles of cytosolic pH, MgATP, L-glutamate and L-aspartate in the co-ordinate control of the PEP branchpoint in ripening bananas. << Less

  Biochem J 352:875-882(2000) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Enzymic synthesis of guanosine and cytidine triphosphates: a note on the nucleotide specificity of the pyruvate phosphokinase reaction.

  STROMINGER J.L.

  Biochim Biophys Acta 16:616-618(1955) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Fluorokinase and pyruvic kinase.

  TIETZ A., OCHOA S.

  Arch Biochem Biophys 78:477-493(1958) [PubMed] [EuropePMC]

  This publication is cited by 5 other entries.

• Enzymatic phosphorylation of adenosine and 2,6-diaminopurine riboside.

  KORNBERG A., PRICER W.E. Jr.

  J Biol Chem 193:481-495(1951) [PubMed] [EuropePMC]

  This publication is cited by 6 other entries.