Carboxylation of phosphoenolpyruvate by extracts of Neisseria gonorrhoeae.

The enzymatic carboxylation of phosphoenolpyruvate by cell-free extracts of Neisseria gonorrhoeae was examined and determined to be similar to the reaction catalyzed by phosphoenolpyruvate carboxylase (PEPC). This was shown by the irreversibility of the reaction and nucleotide independency. The enzyme was found to have some characteristics different from the other bacterial PEPCs reported. The enzyme showed catalytic activity in the presence of cobalt ions as well as magnesium and manganese ions, was not inhibited by succinate in fresh extracts, and displayed a low Michaelis constant for bicarbonate (0.27 mM), as compared with other PEPCs. The significance of this low Michaelis constant is discussed with respect to the growth of the organism and the importance of this enzyme to protein and nucleic acid synthesis.