24 September 2014

Beta Oxidation of Fatty Acids (Short, Medium, and Long Chain)

Beta oxidation is the breakdown of FAs to Acetyl Coa
Learn the steps in Beta Oxidation and how fats are moved into the mitochondria.

Clinical Correlation: What does a high level of dicarboxylic acid found in urine indicate about beta oxidation?

Primary FA breakdown is beta-oxidation
Secondarily – Alpha oxidation or omega oxidation

Long-chain fatty acids are broken down in the peroxisome first (before undergoing beta oxidation)

Major similarity of FA synthesis and Oxidation is the use of Co-enzyme A

Moving Long Chain Fatty Acids into the Mitochondria:
Long chain fatty acid converted to acylCoA by Acyl CoA Synthetase (1st enzyme)
Then Acyl CoA is attached to Carnitine by Carnitine Palmitoyl Transferase 1 (2nd Enzyme)
The Acyl Carnitine is transported through a Translocase (3rd Enzyme)
Inside the matrix, Acyl Carnitine is converted back to Acyl CoA by CPTII (4th Enzyme)
- An error in any of these enzymes can present as a beta oxidation deficiency

Steps in Fatty acid oxidation:
1. Attach FA to CoA
2. Medium and short chain transported into mitochondria – Long chain attached to carnitine
3. Move long chain acylcarnitine into mitochondria
4. Reform Acyl CoA
5. Acyl CoA + FAD yields Trans-enoyl CoA
6. Trans-Enoyl Coa + H2O yields hydroxyacyl CoA
7. HydroxyAcyl CoA + NAD yields Ketoacyl CoA + NADH
8. 3 Ketoacyl CoA + CoA yields Acetyl CoA and Acyl CoA (Shortened by two carbons)


  1. this is very helpful!!! great information and step by step, concise explanation. Thank u!