Medicine & USMLE

Propionic Acid Pathway

Biochemical Pathways
  1. Glycolysis
  2. Citric Acid Cycle (TCA Cycle)
  3. Electron Transport Chain (ETC)
  4. Cori Cycle
  5. De Novo Purine Synthesis
  6. De Novo Pyrimidine Synthesis
  7. Purine Salvage
  8. Purine Excretion
  9. Ethanol Metabolism
  10. Pyruvate Metabolism
  11. HMP Shunt (Pentose Phosphate Pathway)
  12. Galactose Metabolism
  13. Sorbitol (Polyol) Pathway
  14. Urea Cycle
  15. Alanine (Cahill) Cycle
  16. Catecholamine Synthesis & Breakdown
  17. Homocysteine Metabolism
  18. Fatty Acid Synthesis (Citrate Shuttle)
  19. Fatty Acid Breakdown (Carnitine Shuttle)
  20. Propionic Acid Pathway
  21. Fructose Metabolism
  22. Regulation by Fructose-2,6-Bisphosphate (F-2,6-BP)
  23. Glycogenesis
  24. Glycogenolysis


The propionic acid pathway is a biochemical pathway that breaks down fatty acids and certain amino acids into energy. This pathway starts with one of five options: odd-chain fatty acids, as well as the amino acids threonine, isoleucine, valine or methionine.

All of these starting molecules are metabolized into the same molecule, propionyl-CoA. Propionyl-CoA is then converted into methylmalonyl-CoA by propionyl-CoA carboxylase, using biotin or vitamin B7 as a cofactor.

Next, methylmalonyl-CoA is converted into Succinyl-CoA by methylmalonyl-CoA mutase, using cobalamin or vitamin B12 as a cofactor. The final product, Succinyl-CoA is a part of the Krebs cycle, which means that it can be used to produce ATP or glucose by way of gluconeogenesis.