fatty acid oxidation (cmd)

• Fatty Acids


  Carboxylic acids with hydrocarbon chains ranging from 4 to 36 carbons
• Saturated Fatty Acids


  • No double bonds between carbon atoms
  • Example: CH₃-(CH₂)₆-COOH
• Unsaturated Fatty Acids


  • Contain one or more double bonds, which affect the molecule's structure
  • Example: CH₃-CH₂-CH=CH-(CH₂)₄-COOH
• Roles of Fatty Acids

  • Fuel Molecules
  • Precursors for phospholipids and glycolipids
  • Protein Anchorage
  • Hormones and Messengers
• Lipolysis


  Breakdown of triacylglycerols to diacylglycerols, diacylglycerols to monoacylglycerols, and monoacylglycerols to free fatty acids and glycerol
• Enzymes involved in lipolysis

  • Adipose Triglyceride Lipase (ATGL)
  • Hormone-Sensitive Lipase (HSL)
  • Monoglyceride Lipase (MGL)
• Transport in Blood


  Free fatty acids are transported in the bloodstream bound to albumin
• Intracellular Transport


  Fatty Acid Binding Protein (FABP) helps in intracellular transport to target organelles
• Activation of Fatty Acids

  1. Fatty acids are activated by forming a thioester bond with Coenzyme A (CoA), resulting in fatty acyl-CoA

  2. Fatty acyl-CoA synthetase catalyzes this reaction
• Entry of Fatty Acids into Mitochondria

  1. Fatty acyl-CoA is converted to fatty acyl-carnitine by Carnitine Acyltransferase I (CPT I)

  2. Fatty acyl-carnitine is shuttled across the inner mitochondrial membrane by the carnitine/acyl-carnitine translocase

  3. Carnitine Acyltransferase II (CPT II) reconverts fatty acyl-carnitine back to fatty acyl-CoA in the mitochondrial matrix
• β-Oxidation of Fatty Acids


  1. Oxidation

  2. Hydration

  3. Oxidation

  4. Thiolysis
• Oxidation of Unsaturated Fatty Acids

  • Isomerase converts cis double bonds to trans double bonds
  • Reductase reduces certain double bonds that cannot be directly isomerized
• Oxidation of Odd-Chain Fatty Acids

  1. Propionyl-CoA is carboxylated to form D-methylmalonyl-CoA

  2. D-methylmalonyl-CoA is converted to L-methylmalonyl-CoA

  3. L-methylmalonyl-CoA is rearranged to succinyl-CoA

  4. Succinyl-CoA enters the citric acid cycle
• Summary of Fatty Acid Oxidation

  • Activation
  • Transport
  • β-Oxidation
  • Unsaturated and Odd-Chain Fatty Acids