title: Comparative kinetic effects of Mn (II), Mg (II) and the ATP/ADP ratio on phosphoenolpyruvate carboxykinases from Anaerobiospirillum succiniciproducens and Saccharomyces cerevisiae.
abstract: The kinetic affinity for CO(2) of phosphoenolpyruvate PEP(5) carboxykinase from Anaerobiospirillum succiniciproducens, an obligate anaerobe which PEP carboxykinase catalyzes the carboxylation of PEP in one of the final steps of succinate production from glucose, is compared with that of the PEP carboxykinase from Saccharomyces cerevisiae, which catalyzes the decarboxylation of oxaloacetate in one of the first steps in the biosynthesis of glucose. For the A. succiniciproducens enzyme, at physiological concentrations of Mn(2+) and Mg(2+), the affinity for CO(2) increases as the ATP/ADP ratio is increased in the assay medium, while the opposite effect is seen for the S. cerevisiae enzyme. The results show that a high ATP/ADP ratio favors CO(2) fixation by the PEP carboxykinase from A. succiniciproducens but not for the S. cerevisiae enzyme. These findings are in agreement with the proposed physiological roles of S. cerevisiae and A. succiniciproducens PEP carboxykinases, and expand recent observations performed with the enzyme isolated from Panicum maximum (Chen et al. (2002) Plant Physiology 128: 160-164).
authors.affiliation: Departamento de Química, Universidad Metropolitana de Ciencias de la Educación, Avda. J. P. Alessandri 774, Santiago, Chile. Sbazaes@hotmail.com
authors.forename: Sergio
authors.initials: S
authors.lastname: Bazaes
authors.forename: Mauricio
authors.initials: M
authors.lastname: Toncio
authors.forename: Maris
authors.initials: M
authors.lastname: Laivenieks
authors.forename: J Gregory
authors.initials: JG
authors.lastname: Zeikus
authors.forename: Emilio
authors.initials: E
authors.lastname: Cardemil
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry*; D000255:Adenosine Triphosphate / Q000737:chemistry*; D044064:Anaerobiospirillum / Q000378:metabolism*; D002245:Carbon Dioxide / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D007477:Ions; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry*; D008345:Manganese / Q000737:chemistry*; D008670:Metals / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D007477:Ions; D008670:Metals; D002245:Carbon Dioxide; D008345:Manganese; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D008274:Magnesium