Purification of Phosphoenolpyruvate Carboxylase and Characterization of Changes in Oligomerization Using HPLC

Abstract
Maize leaf phosphoenolpyruvate carboxylase and its subunits were chromatographed and extensively purified from crude preparations of the enzyme on a Bio-Sil TSK 400 column. The enzyme (tetramer) showed no adsorption to the column or loss of enzymatic activity. The tetramer complex was dissociated into its dimers and monomers when treated with the thiol oxidant diamide at pH 6.8 and 8.4. The effects of diamide were approximately twice as fast at pH 8.4 than at pH 6.8. Under either condition a certain amount of dimer still remained and could only be further dissociated by heating.