Figure 2.

Energy release from saturated fatty acids in mitochondrial β-oxidation. Fatty acids are released from triacylglycerol by lipolysis or lipophagy and translocated into the mitochondrion. Fatty acid is shortened by two carbons in one β-oxidation cycle; the β-oxidation steps are repeated until only two carbon units remain. The FADH₂ and NADH are utilized to generate ATP in the electron transport chain and acetyl-CoA enters the Krebs cycle. The β-oxidation steps are shown in red italics, numbered 1–4. The number of ATP molecules obtained from β-oxidation and Krebs cycle is shown in red. ATP, adenosine triphosphate; CoA, coenzyme A; FAD and FADH₂, flavin-adenine dinucleotide, oxidized and reduced forms, respectively; NAD⁺ and NADH, nicotinamide adenine dinucleotide, oxidized and reduced forms, respectively.