Fatty Acid Metabolism - Overview

Overview

• Lipolysis is carried out by lipases.
• Once freed from glycerol, free fatty acids can enter blood and muscle fiber by diffusion.
• Beta oxidation splits long carbon chains of the fatty acid into acetyl CoA, which can eventually enter the TCA cycle.

Briefly, β-oxidation or lipolysis of free fatty acids is as follows:

1. Dehydrogenation by acyl-CoA dehydrogenase, yielding 1 FADH₂
2. Hydration by enoyl-CoA hydratase
3. Dehydrogenation by 3-hydroxyacyl-CoA dehydrogenase, yielding 1 NADH
4. Cleavage by thiolase, yielding 1 acetyl-CoA and a fatty acid that has now been shortened by 2 carbons (acyl-CoA)

This cycle repeats until the FFA has been completely reduced to acetyl-CoA or, in the case of fatty acids with odd numbers of carbon atoms, acetyl-CoA and 1 mol of propionyl-CoA per mol of fatty acid.