The formation of propionate and acetate as terminal processes in the energy metabolism of the adult liver fluke Fasciola hepatica

Abstract

1. 1. The formation of propionate from succinate occurs in the mitochondria of the adult common liver fluke essentially by a reversal of the pathway operating in mammalian mitochondria in the conversion of propionate into succinate.

2. 2. The conversion of succinate into its CoA ester is linked by a CoA transferase to the splitting of propionyl-CoA.

3. 3. The total process of propionate synthesis from succinate neither produces nor requires nucleosidetriphosphate energy.

4. 4. The formation of acetate from pyruvate proceeds via acetyl-CoA from which the CoA group is enzymatically transferred to succinate. The succinyl-CoA produced in this way is converted into succinate coupled with the synthesis of ATP.

5. 5. The energy yield of the anaerobic mitochondrial conversion of malate into acetate and propionate is one ATP per malate consumed.