Fatty Acid Oxidation: Mechanisms and Clinical Significance

Fatty Acid Oxidation

Metabolic pathway for fatty acid energy production.

Beta-Oxidation

Process of breaking down fatty acids in mitochondria.

Acetyl-CoA

Two-carbon molecule entering the citric acid cycle.

Carnitine Shuttle

Transport system for long-chain fatty acids into mitochondria.

Acyl-CoA Synthetase

Enzyme activating fatty acids to form fatty acyl-CoA.

CPT-I

Converts fatty acyl-CoA to fatty acylcarnitine.

Carnitine Acylcarnitine Translocase

Transports fatty acylcarnitine across mitochondrial membrane.

CPT-II

Converts fatty acylcarnitine back to fatty acyl-CoA.

β-Oxidation Enzymes

Catalyze removal of two-carbon units from fatty acyl-CoA.

FAD

Coenzyme accepting electrons during β-oxidation.

NAD+

Coenzyme accepting electrons in oxidation steps.

Oxidation Step

Formation of trans-Δ2-enoyl-CoA from acyl-CoA.

Hydration Step

Water addition forming L-β-hydroxyacyl-CoA.

Thiolysis Step

Cleavage releasing acetyl-CoA and shortened fatty acyl-CoA.

Stoichiometry of Oxidation

Quantifies products from saturated fatty acid oxidation.

Energy Yield

Total ATP produced from complete fatty acid oxidation.

Malonyl-CoA

Inhibits CPT-I, regulating fatty acid entry.

High ATP/ADP Ratio

Inhibits citric acid cycle and β-oxidation.

Unsaturated Fatty Acids

Require special enzymes for oxidation due to double bonds.

Enoyl-CoA Isomerase

Converts cis-Δ3-enoyl-CoA to trans-Δ2-enoyl-CoA.

Odd-Chain Fatty Acids

Yield propionyl-CoA, converted to succinyl-CoA.

Propionyl-CoA Carboxylase

Converts propionyl-CoA to methylmalonyl-CoA.

Peroxisomal β-Oxidation

Shortens very long-chain fatty acids for mitochondrial use.

Carnitine Deficiency

Impaired fatty acid transport causing energy production issues.

MCAD Deficiency

Inherited disorder affecting medium-chain fatty acid oxidation.

Zellweger Syndrome

Peroxisomal disorder affecting VLCFA oxidation.

Diabetic Ketoacidosis

Increased fatty acid oxidation leads to ketone overproduction.

ATP Yield from Acetyl-CoA

Each acetyl-CoA produces 10 ATP in the cycle.

Total ATP from Palmitoyl-CoA

Complete oxidation yields 106 ATP after activation.