Reactome: A Curated Pathway Database

Mitochondrial Fatty Acid Beta-Oxidation

Stable Identifier
R-HSA-77289
Type
Pathway
Species
Homo sapiens
Compartment
Locations in the PathwayBrowser
Summation

Beta-oxidation begins once fatty acids have been imported into the mitochondrial matrix by carnitine acyltransferases. The beta-oxidation spiral of fatty acids metabolism involves the repetitive removal of two carbon units from the fatty acyl chain. There are four steps to this process: oxidation, hydration, a second oxidation, and finally thiolysis. The last step releases the two-carbon acetyl-CoA and a ready primed acyl-CoA that takes another turn down the spiral. In total each turn of the beta-oxidation spiral produces one NADH, one FADH2, and one acetyl-CoA.

Further oxidation of acetyl-CoA via the tricarboxylic acid cycle generates additional FADH2 and NADH. All reduced cofactors are used by the mitochondrial electron transport chain to form ATP. The complete oxidation of a fatty acid molecule produces numerous ATP molecules. Palmitate, used as the model here, produces 129 ATPs.

Beta-oxidation pathways differ for saturated and unsaturated fatty acids. The beta-oxidation of saturated fatty acids requires four different enzymatic steps. Beta-oxidation produces and consumes intermediates with a trans configuration; unsaturated fatty acids that have bonds in the cis configuration require three separate enzymatic steps to prepare these molecules for the beta-oxidation pathway.

Literature References
PubMed ID Title Journal Year
11826276 Fatty acid oxidation disorders. Annu Rev Physiol 2002
7951672 Genetic disorders of mitochondrial fatty acid oxidation. Curr Opin Pediatr 1994
1431593 Molecular basis of mitochondrial fatty acid oxidation defects. J Lipid Res 1992
10527676 Recent developments in the investigation of inherited metabolic disorders using cultured human cells. Mol Genet Metab 2000
  The Metabolic and Molecular Bases of Inherited Disease, 8th ed   2001
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