Recording-2025-02-17T09:50:11.099Z

Beta Oxidation

  • Definition: Beta oxidation is the metabolic process through which fatty acids are broken down in the mitochondria to generate acetyl CoA, NADH, and FADH2.

Process Overview

  • Unlike fatty acid synthesis, which involves the building of fatty acids, beta oxidation focuses on the breakdown.

  • This cycle occurs in the mitochondria and is essential for energy production during fasting, prolonged exercise, or when carbohydrates are low.

Steps of Beta Oxidation

  1. Activation of Fatty Acids

    • Fatty acids are activated by the conversion to acyl-CoA in the cytoplasm before they enter the mitochondria.

    • Enzyme: Acyl-CoA synthetase.

  2. Transport into Mitochondria

    • Fatty acyl-CoA is transported into mitochondria via the carnitine shuttle.

    • Carnitine acyltransferase I facilitates the exchange of CoA for carnitine, allowing for mitochondrial entry.

  3. The Beta Oxidation Cycle

    • Each cycle removes two carbon atoms from the fatty acyl-CoA.

    • It consists of four enzymatic steps:

      1. Dehydrogenation: Introduces a double bond between the alpha and beta carbons; forms trans-Δ2-enoyl-CoA. Enzyme: acyl-CoA dehydrogenase.

      2. Hydration: Adds water across the double bond to form L-β-hydroxyacyl-CoA. Enzyme: enoyl-CoA hydratase.

      3. Another Dehydrogenation: Converts β-hydroxyacyl-CoA to β-ketoacyl-CoA; reduces NAD+ to NADH. Enzyme: β-hydroxyacyl-CoA dehydrogenase.

      4. Thiolysis: Cleaves β-ketoacyl-CoA with