The effect of malate and other dicarboxylic acids on mitochondrial isocitrate metabolism.

The increased isocitrate consumption of isolated rat liver mitochondria brought about by the addition of L-malate is quantitatively accounted for by increases in the production of both a-ketoglutarate and citrate. The effect on citrate production is still observed under conditions such that the oxidation of isocitrate to a-ketoglutarate is completely inhibited. The specificity of the effect has been investigated, and it is shown that a number of dicarboxylic acids can stimulate isocitrate metabolism in a similar fashion. Marked stereospecificity is indicated by the fact that among the tartrate stereoisomers only the meso form is active.