USMLE

Propionic Acid Pathway

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

Summary

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.