When fatty acids are oxidized, they undergo a process called β-oxidation, primarily within the mitochondria. This metabolic pathway breaks down fatty acids into two-carbon acetyl-CoA molecules. These acetyl-CoA molecules then enter the citric acid cycle (Krebs cycle) and oxidative phosphorylation, ultimately producing large amounts of energy in the form of ATP (adenosine triphosphate), along with carbon dioxide and water.
The β-Oxidation Process: A Step-by-Step Overview
- Activation: Fatty acids are activated by combining with coenzyme A (CoA) to form fatty acyl-CoA. This requires energy in the form of ATP.
- Transport: Long-chain fatty acids require carnitine to be transported across the mitochondrial membrane for β-oxidation to occur.
- β-Oxidation Cycle: The fatty acyl-CoA undergoes a cyclical series of four reactions: oxidation, hydration, oxidation, and thiolysis. Each cycle shortens the fatty acid chain by two carbons, generating one molecule of acetyl-CoA, one NADH, and one FADH2.
- Energy Production: The NADH and FADH2 produced enter the electron transport chain, driving ATP synthesis. Acetyl-CoA enters the citric acid cycle, further contributing to ATP production.
Location and Significance of Fatty Acid Oxidation
- Mitochondria: The primary site for fatty acid oxidation is the mitochondria, often referred to as the "powerhouse" of the cell. The process generates a significant amount of ATP compared to carbohydrate oxidation. Mitochondrial β-oxidation is the pathway by which fatty acids are fully oxidized to carbon dioxide and water, ultimately yielding more energy per mole and per gram of fatty acid than is released from complete oxidation of carbohydrate.
- Peroxisomes: Fatty acid oxidation also occurs in peroxisomes, though primarily for very long-chain fatty acids. Fatty acid beta-oxidation occurs in both mitochondria and peroxisomes. Mitochondria catalyze the beta-oxidation of the bulk of short-, medium-, ...
- Energy Production: Fatty acid oxidation is crucial for providing energy, particularly during prolonged exercise or fasting, when glucose stores are depleted. Exercise intensity and duration are important determinants of fat oxidation. Fat oxidation rates increase from low to moderate intensities and then decrease...
Beyond Energy: Other Roles of Oxidized Fatty Acids
Oxidized fatty acids also play signaling roles in various cellular processes, including inflammation and immune responses. Oxidized fatty acids are important signalling molecules in inflammation and other immune pathways in that if they are present, cells will kick off potentially...
