text: There are several different pathways through which propionyl-CoA can be produced:
  * Propionyl-CoA, a three-carbon structure, is considered to be a minor species of propionic acid. Therefore, odd-number chains of fatty acids are oxidized to yield both propionyl-CoA as well as acetyl-CoA. Propionyl-CoA is later converted into succinyl-CoA through biotin-dependant propionyl-CoA carboxylase (PCC) and b12-dependant methylmalonyl-CoA mutase (MCM), sequentially.
  * Propionyl-CoA is not only produced from the oxidation of odd-chain fatty acids, but also by the oxidation of amino acids including methionine, valine, isoleucine, and threonine. Furthermore, catabolism of amino acids can also be a result of the conversion of propionyl-CoA to methylmalonyl-CoA by propionyl-CoA carboxylase.
  * Cholesterol oxidation, which forms bile acids, also forms propionyl-CoA as a side product. In an experiment performed by Suld et al., when combining liver mitochondria and propionic acid with the addition of coenzyme A, labeled isotopes of psionic acid were degraded. However, following 5β-cholestane-3α,7α,12α,26-tetrol-26,27-C14 incubation, propionyl CoA was able to be rescued along with the formation of bile.