Its conjugate base α-ketobutyrate is the predominant form found in nature (near neutral pH).

α-Ketobutyrate is transported into the mitochondrial matrix, where it is converted to propionyl-CoA by branched-chain alpha-keto acid dehydrogenase complex.

This is first through the enzyme mitochondria propionyl-CoA carboxylase with biotin as a cofactor to produce (S)-methylmalonyl-CoA.

Finally, mitochondrial methylmalonyl-CoA mutase with cofactor adenosylcobalamin produces succinyl-CoA which enters the citric acid cycle.

[1] Vin jaune is marked by the formation of sotolon from alpha-ketobutyric acid.