PathwayStep1329 PathwayStep1336 PathwayStep1340 mitochondrial fatty acid beta-oxidation of unsaturated fatty acids Propionyl-CoA catabolism mitochondrial fatty acid beta-oxidation of saturated fatty acids Mitochondrial Fatty Acid Beta-Oxidation Authored: Gillespie, ME, 2003-09-19 00:00:00 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.<p>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.<p>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. Edited: Gillespie, ME, 0000-00-00 00:00:00 GENE ONTOLOGYGO:0006635 ISBN0079130356 Pubmed10527676 Pubmed11826276 Pubmed1431593 Pubmed7951672 Reactome Database ID Release 4377289 Reactome, http://www.reactome.org ReactomeREACT_1473