The four reactions of beta-oxidation

Fatty acid oxidation is dependent on entry of fatty acids into the mitochondria, which provides substrate for beta-oxidation in the mitochondrial matrix. The fatty acids are transported in as acylcarnitines.

Step 1 in beta-oxidation happens when a fatty acyl CoA that’s made at the inner surface of the inner mitochondrial membraine is oxidized by acyl-CoA dehydrogenase. The flavoprotein enzyme uses FAD to accept an electron to complete the reaction. The products end up being trans-enoyl CoA and FADH2, which transfers electrons into the oxidative phosphorylation pathway to recreate FAD.

Step 2 in beta-oxidation is hydration of trans-enoyl CoA producing 3-L-hydroxyacyl CoA.

Step 3 is when 3-L-hydroxyacyl CoA is oxidized to 3-ketoacyl-CoA intermediate and generates NADH.

Step 4 occurs when beta-ketoacyl-CoA thiolase cleaves the 3-ketoacyl-CoA to produce a 2-carbon atom short fatty acyl-CoA and acetylCoA.

Acetyl CoA is then ready to enter in the TCA cycle for ATP energy production, and FADH2 and NADH will also be reoxidzed in the ETS to produce ATP energy.



Published by David Despain, MS, CFS

David is a science and health writer living on Long Island, New York. He's written for a variety of publications including Scientific American, Outside Online, the American Society for Nutrition's (ASN) Nutrition Notes Daily, and Institute of Food Technologists' (IFT) Food Technology magazine and Live! blog. He's also covered new findings reported at scientific meetings including Experimental Biology, AAAS, AOCS, CASW, Sigma Xi, IFT, and others on his personal blog "Evolving Health." David is also an active member of organizations including the National Association of Science Writers (NASW), the American Association for the Advancement of Science (AAAS), the American Society for Nutrition, the Institute of Food Technologists, and the National Audubon Society. David has a master's degree in human nutrition from the University of Bridgeport, and a bachelor's degree in English from University of Illinois at Springfield. He also earned his Certified Food Scientist credential from the Institute of Food Technologists.

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