Some properties of the malic enzyme of pigeon liver. 2. Synthesis of malate from pyruvate

I9595. D-and L-Lactate, pyruvate and DL-Xh- hydroxybutyrate inhibited slightly at high con- centrations.Propionate and DL-B-hydroxybutyrate were not inhibitory at the same concentrations.6. Citrate and fluorocitrate also inhibited malate decarboxylation.For equal inhibition, the con- centration of citrate required was over ten times that of the fluorocitrate.7. The inhibition by di-and tri-carboxylic acids was partly reversed by addition of Mn2+ (or Mg2+) ions and partly by raising the substrate concentra- tion.The data are in accordance with the view that the inhibitions are due partly to chelation of the bivalent cations required as cofactors and partly to competition with the malate for the enzyme- binding site.