title: Regulation of phosphoenolpyruvate carboxylase from maize leaves by nitrate and alanine.
abstract: Nitrate and alanine were found to stimulate partially purified maize leaf phosphoenolpyruvate carboxylase under specific assay conditions. Both metabolites stimulated the enzyme at low pH (7.0-7.5) and low substrate levels (1mM phosphoenolpyruvate). Nitrate was found to have a biphasic effect on the enzyme, stimulating at low concentrations (1mM-3mM), with a decrease in stimulation at higher levels. Nitrate caused inhibition of activity at pH 8.0 and although alanine caused some stimulation in activity at pH 8.0 this was not as marked as at the lower pH levels.
authors.affiliation: Department of Botany, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: L
authors.initials: L
authors.lastname: Garson
authors.forename: V
authors.initials: V
authors.lastname: Gray
mesh_terms: D000409:Alanine / Q000494:pharmacology*; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009566:Nitrates / Q000494:pharmacology*; D010730:Phosphoenolpyruvate Carboxylase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D003313:Zea mays / Q000201:enzymology*
chemical_list: D009566:Nitrates; D010730:Phosphoenolpyruvate Carboxylase; D000409:Alanine