Inhibition of phosphoenolpyruvate carboxylase from maize by 2-phosphoglycollate.

The phosphoenolpyruvate carboxylase from maize leaf was strongly inhibited by 2-phosphoglycollate. The pH of the reaction did not influence the extent of inhibition by 2-phosphoglycollate. The kinetic analysis of the inhibition data by Lineweaver-Burk method showed that 2-phosphoglycollate inhibition was competitive with respect to phosphoenolpyruvate. The secondary plot of the data showed nonlinearity indicating that there may be two 2-phosphoglycollate binding sites with Ki values of 0.4 mM and 0.16 mM. The biphasic nature of the inhibition was also evident when the data were plotted using the method of Dixon. 2-phosphoglycollate inhibition was uncompetitive with respect to Mg(2+) suggestting that it binds only to enzyme-Mg(2+) complex.