Characterization of Phosphoenolpyruvate Carboxykinase from Panicum maximum

Abstract
Phosphoenolpyruvate carboxykinase, EC 4.1.1.32 (PEPCK), was purified 43-fold from the grass Panicum maximum. Michaelis constants (Km) were determined for the exchange reaction, the carboxylation reaction, and the decarboxylation reaction. The Km values for oxaloacetate and ATP in the decarboxylation reaction were found to be lower than the Km values for the substrates used in the exchange reaction and in the carboxylation reaction. Phosphoenolpyruvate carboxylase was not detectable in the purified PEPCK preparation.