The degradation of isoleucine starts either in the mitochondria or the cytosol. L-isoleucine reacts with 2-oxoglutarate through a branch-chain amino acid aminotransferase resulting in the release of L-glutamate and 3-methyl-2-oxopentanoate. The latter compound reacts with 2-oxoisovalerate carboxy-lyase resulting in the release of carbon dioxide and methylbutanoyl. Methylbutanol reacts with oxidized flavoproteins resulting in the release of a reduced flavoprotein and tiglyl-CoA. The latter then reacts with water resulting in the release of 2-methyl-3-hydroxybutyryl-CoA. The latter compound reacts with NAD resulting in the release of NADH, hydrogen ion and 2-methylacetoacetyl-CoA. The latter then reacts with a Coenzyme A resulting in the release of propanoyl-CoA and acetyl-CoA. This degradation pathways may be an important detoxification mechanism to prevent the build up of branched chain aminoacids and their derived alpha-keto acids which are cytotoxic.

Isoleucine Degradation References