Question

The branched-chain α-keto acid dehydrogenase complex, which participates in amino acid catabolism, contains the same three types of enzymes as are in the pyruvate dehydrogenase and the α-ketoglutarate dehydrogenase complexes. Draw the reaction product when valine is deaminated as in the glutamate⇌α-ketoglutarate reaction (Section 17-5A) and then is acted on by the branched-chain α-keto acid dehydrogenase.

Short answer

The BCKDC or BCKDH complex (branched-chain ketoacid dehydrogenase complex) is a multi-subunit enzyme complex located on the mitochondrial inner membrane.The oxidative decarboxylation of branched, short-chain alpha- keto acids is catalyzed by this enzyme complex.

Step-by-step solution

Step1: Definition of branched-chain –ketoacid dehydrogenase complex

The BCKDC or BCKDH complex (branched-chain ketoacid dehydrogenase complex) is a multi-subunit enzyme complex located on the mitochondrial inner membrane.The oxidative decarboxylation of branched, short-chain alpha- keto acids is catalyzed by this enzyme complex.

The reaction product when valine is deaminated and then is acted on by the branched-chain α-keto acid dehydrogenase

The alpha ketoacid dehydrogenase complex catalyzes the oxidative decarboxylation of a -keto acid, yielding in succinyl-CoA, a high-energy thioester. The amino group of valine is removed during deamination. The deaminated valine is then added to succinyl-CoA. The chemical that results is a thioester of succinyl-CoA and valine:

Hence, the product is made up of succinyl Co-A thioester and deaminated valine.