Characterization of phosphoenolpyruvate carboxylase from mature maize seeds: Properties of phosphorylated and dephosphorylated forms

0350036 - ÚEB 2011 RIV FR eng J - Journal Article
Černý, M. - Doubnerová, V. - Müller, Karel - Ryšlavá, H.
Characterization of phosphoenolpyruvate carboxylase from mature maize seeds: Properties of phosphorylated and dephosphorylated forms.
Biochimie. Roč. 92, č. 10 (2010), s. 1362-1370. ISSN 0300-9084. E-ISSN 1638-6183
R&D Projects: GA MŠMT 1M0505
Institutional research plan: CEZ:AV0Z50380511
Keywords : Phosphoenolpyruvate carboxylase * Phosphorylation * Seed
Subject RIV: EI - Biotechnology ; Bionics
Impact factor: 3.787, year: 2010

Phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) from mature maize seeds (Zea mays L.) was purified to homogeneity and a final specific activity of 13.3 mmol min-1 mg-1. Purified PEPC was treated with phosphatase from bovine intestinal mucosa or protein kinase A to study its apparent phosphorylation level. Kinetic parameters of the enzyme reaction catalyzed by phosphorylated and dephosphorylated forms under different conditions were compared, as well as an effect of modulators. The enzyme dephosphorylation resulted in the change of hyperbolic kinetics to the sigmoidal one (with respect to PEP), following with the decrease of maximal reaction rate and the increase of sensitivity to L-malate inhibition. The hyperbolic kinetics of native PEPC present in dry maize seeds was not changed after the protein kinase A treatment, while it was converted to the sigmoidal one after dephosphorylation. Level of PEPC phosphorylation was not affected during seed imbibition.
Permanent Link: http://hdl.handle.net/11104/0190137