15.10.1: Fatty Acid Oxidation
- Page ID
- 337688
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The process of fatty acid oxidation, called beta oxidation, is fairly simple. The reactions all occur between carbons 2 and 3 (with #1 being the one linked to the CoA) and sequentially include the following:
- dehydrogenation to create \(\text{FADH}_2\) and a fatty acyl group with a double bond in the trans configuration;
- hydration across the double bond to put a hydroxyl group on carbon 3 in the L configuration;
- oxidation of the hydroxyl group to make a ketone; and
- thiolytic cleavage to release acetyl-CoA and a fatty acid two carbons shorter than the starting one.
Reactions two and three in beta oxidation are catalyzed by enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase, respectively. The latter reaction yields an NADH. The final enzyme of beta oxidation is thiolase and this enzyme is notable in not only catalyzing the formation of acetyl-CoAs in beta oxidation, but also catalyzing the joining of two acetyl-CoAs (essentially the reversal of the last step of beta oxidation) to form acetoacetyl-CoA– essential for the pathways of ketone body synthesis and cholesterol biosynthesis.