Fatty acid beta-oxidation pathway enzyme

Fatty acid beta‐oxidation pathway enzymes are a group of mitochondrial and peroxisomal enzymes responsible for the stepwise breakdown of long‐chain fatty acids to generate acetyl‐CoA, NADH, and FADH₂. This process is essential for cellular energy production during periods when glucose is scarce—such as fasting or prolonged exercise. The canonical sequence involves four recurring steps catalyzed by distinct enzymes: 1. Acyl‐CoA dehydrogenases initiate β‐oxidation by introducing a double bond at the β position; multiple isoforms exist based on chain length specificity. 2. Enoyl‐CoA hydratase hydrates the double bond to form L-hydroxyacyl CoA. 3. Hydroxyacyl‐CoA dehydrogenase oxidizes this intermediate to a keto group while generating NADH. 4. Ketoacyl‐CoA thiolase cleaves off an acetyl Co-A unit from the shortened acyl chain. The process repeats until all carbons are converted into acetyl Co-A units that feed into the citric acid cycle for further ATP generation via oxidative phosphorylation. Deficiencies in individual enzymes can cause severe metabolic diseases such as medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD), which may present with hypoglycemia and sudden death if untreated. While not typically targeted directly by drugs, inhibitors like etomoxir can block upstream transport steps to modulate overall pathway activity for research purposes or experimental therapies.

Other names

Beta-oxidation enzymeFatty acid oxidation enzymeAcyl-CoA dehydrogenase (family)Enoyl-CoA hydrataseHydroxyacyl-CoA dehydrogenaseKetoacyl-CoA thiolase

Inhibition of fatty acid entry into mitochondria by blocking CPT1 reduces beta oxidation and shifts energy metabolism. Note: No approved drugs directly inhibit the main mitochondrial beta oxidation enzymes in clinical use.