Fatty Acid Oxidation
Lipid Biosynthesis
What is the total energy yield (number of ATPs) from oxidizing one molecule of palmitic acid to CO2? Palmitic acid has 16 carbons, so you can break it down into eight acetyl-CoA molecules, with the formation of one FADH2 and one NADH at each of the seven β-oxidation steps. Electron transport starting with FADH2 yields two ATPs and with NADH yields three ATPs. Therefore, β-oxidation yields the equivalent of 35 ATPs per molecule of palmitic acid. Each acetyl-CoA goes into the TCA cycle, where its metabolism yields three NADHs, one FAD, and one GTP directly, for a total of 12 ATPs. Thus, the ATPs produced are:
7 × 5 + 8 × 12 = 35 + 96 = 131
Two ATP equivalents were used to activate the fatty acid, leading to a total energy yield of 129 ATPs, over three times the amount of energy obtained from metabolizing a single molecule of glucose.
