Mitochondrial and peroxisomal fatty acid beta-oxidation enzymes (FAO enzymes)

Mitochondrial and peroxisomal fatty acid beta-oxidation enzymes are a group of catalytic proteins responsible for the breakdown of fatty acids into acetyl-CoA, a critical process for cellular energy production. In mitochondria, these enzymes process short-, medium-, and long-chain fatty acids through a repeating four-step cycle (oxidation, hydration, oxidation, and thiolysis) to generate NADH, FADH2, and acetyl-CoA for the citric acid cycle (StatPearls, 2023). Peroxisomal beta-oxidation enzymes perform a similar function but are specialized for the chain-shortening of very-long-chain fatty acids (VLCFAs) and branched-chain fatty acids, which are then transferred to mitochondria for complete oxidation (Wanders & Waterham, 2006). Genetic defects in these enzymes lead to serious metabolic disorders, such as Medium-Chain Acyl-CoA Dehydrogenase (MCAD) deficiency, which can cause life-threatening hypoglycemia and liver dysfunction (Houten & Wanders, 2010). In clinical practice, these enzymes are targeted to modulate metabolic flux; for example, partial fatty acid oxidation (pFOX) inhibitors like ranolazine are used to treat angina by reducing fatty acid oxidation in favor of more oxygen-efficient glucose oxidation (Kantor et al., 2000). Conversely, fibrates are used to induce the expression of these enzymes via PPAR-alpha activation to treat hypertriglyceridemia and improve lipid profiles (Lopaschuk et al., 2010).

Other names

Fatty acid beta-oxidation enzymesFAO enzymesMitochondrial beta-oxidation systemPeroxisomal beta-oxidation systempFOX enzymes

Inhibition of specific enzymes like 3-ketoacyl-CoA thiolase (pFOX inhibition) to shift cardiac metabolism toward glucose oxidation; transcriptional induction via PPAR-alpha activation to enhance lipid clearance.