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While searching for literature on ketone bodies, I can only seem to find how they are synthesized, but not how they are broken down. I'm looking for the series of events with enzyme names and intermediates. Does anyone have this?

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First, there are three ketone bodies: Acetone (top), acetoacetic acid (middle), and beta-hydroxybutyric acid (bottom), see the illustration from the Wikipedia:

enter image description here

The second and the third are taken up by heart and brain cells and then converted into Acetyl-CoA which is fed into the citric acid cycle where it is further metabolized. Acetone is mostly excreted. See here for some more information.

Aceto acetic acid is either converted into acetone and removed from the body or enzymatically converted into beta-hydroxybutyric acid by the beta-hydroxybutyrate dehydrogenase. The third possibility is that it is converted into Acetyl-CoA. See the figure for the scheme:

enter image description here

For a more detailed explanation of this process (both, the generation and the metabolization of the ketone bodies) see here.

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  • $\begingroup$ You say the second and third are taken up by heart and brain cells. Aren't they also used by muscle cells during starvation? $\endgroup$ – Paze Apr 7 '15 at 17:11
  • $\begingroup$ During starvation/fasting* $\endgroup$ – Paze Apr 7 '15 at 17:19
  • $\begingroup$ @Paze - muscle cells predominately continue to oxidize fatty acids in the fasting/starvation state $\endgroup$ – Vance L Albaugh Nov 25 '15 at 3:52

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