Purification and characterization of cytosol phosphoenolpyruvate carboxykinase from bullfrog (Rana catesbeiana) liver.
Cytosol PEP carboxykinase has been purified to electrophoretic homogeneity from bullfrog liver homogenate. The enzyme is a single polypeptide chain with a molecular weight of approximately 72,000-75,000. The purified enzyme catalyzed oxaloacetate decarboxylation (nucleoside triphosphate-supported), phosphoenolpyruvate carboxylation, and an exchange reaction between oxaloacetate and [14C]HCO3-in the presence of ITP or CTP. Manganese is absolutely required for the enzyme-catalyzed phosphoenolpyruvate carboxylation, whereas it can be replaced by Mg2+ for the oxaloacetate decarboxylation and the exchange reaction. The optimal pH of each reaction is dependent on the divalent metal ion used. The dependence of the enzyme activity on Mn2+ is markedly different in the phosphoenolpyuvate carboxylation and the oxaloacetate decarboxylation reactions.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001001:Anura; D003600:Cytosol / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D008970:Molecular Weight; D010729:Phosphoenolpyruvate Carboxykinase (GTP) / Q000302:isolation & purification / Q000378:metabolism*; D011892:Rana catesbeiana
D000596:Amino Acids; D008345:Manganese; D010729:Phosphoenolpyruvate Carboxykinase (GTP); D008274:Magnesium