Odd-chain fatty acids, oxidation

Propionyl-CoA is produced as an intermediate of odd chain fatty acid oxidation. Propionyl-CoA is produced by thiolytic cleavage of the five-carbon homolog of acetoacetyl-CoA (see here). 

F. 20.19. Major anaplerotic pathways of the TCA cycle. 1 and 3 (blue arrows) are the two major anabohc pathways. (1) Pyruvate carboxylase (2) Glutamate is reversibly converted to a-ketoglutarate by transaminases (TA) and glutamate dehydrogenase (GDH) in many tissues. (3) The carbon skeletons of valine and isoleucine, a 3-carbon unit from odd chain fatty acid oxidation, and a number of other comprounds enter the TCA cycle at the level of succinyl CoA. Other amino acids are also degraded to fumarate (4) and oxaloacetate (5), principally in the liver. 

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