Differential response of mitochondrial and glyoxysomal citrate synthase to ATP

Abstract

Citrate synthase (EC 4.1.3.7) in glyoxysomes and mitochondria from endosperms of 4-day-old castor bean seedlings was examined for inhibition by ATP. The mitochondrial enzyme responded in the way reported previously for enzymes of animal, plant and yeast origin; that is, inhibition occurred and was competitive with respect to acetyl-CoA. On the other hand, the glyoxysomal enzyme was not inhibited. Since the function of mitochondria is to generate biochemical energy, as ATP, while that of the glyoxysome is to convert acetyl-CoA to succinate, the above results support the interpretation that inhibition of mitochondrial citrate synthase by ATP has regulatory significance. © 1972.