Use numbers to indicate the order of steps in the pyruvate dehydrogenase complex: 1. Decarboxylation of pyruvate to an aldehyde 2. Formation of acetyl CoA 3. Regeneration of the oxidized FAD cofactor 4. Oxidation of aldehyde to a carboxylic acid 5. Reoxidation of the lipoamide cofactor

1-4-2-3-5

Explanation:

The PDHC is made up of multiple copies of 3 different enzymes: pyruvate dehydrogenase (PDH, E1: 20-30 copies), dihydrolipoamide S-acetyltransferase (DLAT, E2: 60 copies) and dehydrogenase dihydrolipoamide, (DLD, E3: 6 copies). The complex also requires five different coenzymes: CoA, NAD +, FAD +, lipoic, and thiamine pyrophosphate (TPP). Three of the complex coenzymes are closely linked to the complex enzymes (TPP, lipoic acid, and FAD +) and two are used as carriers of the products of PDHC activity (CoA and NAD +). The pathway for oxidation of PDH from pyruvate to acetyl-CoA is a diagram below.