PROPIONATE PATHWAY METABOLITES AS REGULATORS OF FATTY AND DICARBOXYLIC-ACID OXIDATION IN LIVER-MITOCHONDRIA

The functioning of the propionate pathway of oxidation substrate metab olism was studied in the norm and under vitamin B-12 deficiency. The p athway was shown to play an important role in the proper oxidative pro cess since its inhibition in B-12-deficient animals results in a decre ase in respiration, palmitoylcarnitine and succinate oxidation rates, and coupling of oxidative phosphorylation. Succinate, the end product of the propionate pathway, normalizes respiration and restores the rat e of palmitoylcarnitine oxidation in B-12-deficient animals, showing i ts crucial role in the propionate pathway. In vivo propionate inhibits , whereas methyl malonate stimulates, palmitoylcarnitine respiration, but only in control animals. In B-12-deficient animals the sensitivity to these metabolites is decreased.