Some Properties of Pea Mitochondrial Phospho-Pyruvate Dehydrogenase-Phosphatase 1
AUTOR(ES)
Miernyk, Jan A.
RESUMO
Reactivation of the pea mitochondrial pyruvate dehydrogenase complex was the result of dephosphorylation catalyzed by phospho-pyruvate dehydrogenase-phosphatase, an intrinsic component of the complex. Phosphatase activity was dependent upon divalent metal ions, with Mg2+ more effective than Mn2+ or Co2+. The Michaelis constants for Mg2+, Mn2+, and Co2+ were 3.8, 1.7, and 1.4 millimolar, respectively. Neither the rate nor the extent of activation of the phosphatase by Mg2+ or Mn2+ was effected by up to 100 units per assay of megamodulin. Calcium ions did not activate pea mitochondrial phospho-pyruvate dehydrogenase-phosphatase, and low concentrations of Ca2+ antagonized activation by other divalent cations. Phosphatase activity was inhibited by fluoride and ortho-phosphate but not by molybdate or vanadate. Krebs cycle intermediates, adenylates, polyamines, amino acids, and phosphoamino acids were without effect upon pea mitochondrial phospho-pyruvate dehydrogenase-phosphatase activity in vitro.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1056354Documentos Relacionados
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