title: Inactivation of maize phosphoenolpyruvate carboxylase by urea.
abstract: Phosphoenolpyruvate carboxylase purified from leaves of maize (Zea mays, L.) is sensitive to the presence of urea. Exposure to 2.5 m urea for 30 min completely inactivates the enzyme, whereas for a concentration of 1.5 m urea, about 1 h is required. Malate appears to have no effect on inactivation by urea of phosphoenolpyruvate carboxylase. However, the presence of 20 mm phosphoenolpyruvate or 20 mm glucose-6-phosphate prevents significant inactivation by 1.5 m urea for at least 1 h. The inactivation by urea is reversible by dilution. The inhibition by urea and the protective effects of phosphoenolpyruvate and glucose-6-phosphate are associated with changes in aggregation state.
authors.affiliation: Department of Biochemistry, University of California, Riverside, California 92521.
authors.forename: R T
authors.initials: RT
authors.lastname: Wedding
authors.forename: P
authors.initials: P
authors.lastname: Dole
authors.forename: T P
authors.initials: TP
authors.lastname: Chardot
authors.forename: M X
authors.initials: MX
authors.lastname: Wu