Reactome | Mitochondrial Fatty Acid Beta-Oxidation

Mitochondrial Fatty Acid Beta-Oxidation

Stable Identifier

R-HSA-77289

DOI

10.3180/REACT_1473.1

Type

Pathway

Species

Homo sapiens

Compartment

mitochondrial matrix

ReviewStatus

5/5

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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
1431593	Molecular basis of mitochondrial fatty acid oxidation defects. Coates, PM, Tanaka, K	J Lipid Res	1992
11826276	Fatty acid oxidation disorders. Rinaldo, P, Bennett, MJ, Matern, D	Annu Rev Physiol	2002
	The Metabolic and Molecular Bases of Inherited Disease, 8th ed Beaudet, AL, Scriver, CR, Sly, WS, Valle, D		2001
10527676	Recent developments in the investigation of inherited metabolic disorders using cultured human cells. Roe, CR, Roe, DS	Mol Genet Metab	2000
7951672	Genetic disorders of mitochondrial fatty acid oxidation. Hale, DE, Stanley, CA	Curr Opin Pediatr	1994