Acetaldehyde thiamine pyrophosphate complex

The active acetaldehyde -thiamine pyrophosphate complex then reacts enzymically with another co-factor lipoic acid (6,8-dithiooct2moic acid), or lipoamide, since in its active state inside the cells the acid exists in an amide linkage with a lysine residue of a specific protein... 

Removal of CO2 from pyruvate. This reaction is carried out by the pyruvate decarboxylase (El) component of the complex. Like yeast pyruvate decarboxylase, responsible for the production of acetaldehyde, the enzyme uses a thiamine pyrophosphate cofactor and oxidizes the carboxy group of pyruvate to CO2. Unlike the glycolytic enzyme, acetaldehyde is not released from the enzyme along with CO2. Instead, the acetaldehyde is kept in the enzyme active site, where it is transferred to Coenzyme A. 

---