General Information (veiwing the enzyme will be easier if you scroll the picture all the way to the right)
Dihydrolipoamide dehydrogenase is a member a the family of enzymes collectively known as disulfied oxidoreductases. Members of this group utilize disulfide complexes in the reduction and/or oxidation of substrates. Dihydrolipoamide dehydrogenase is found in multiple catalytic enzyme complexes, including 2-oxoglutarate dehydrogenase complex, alpha-ketoglutarate dehydrogenase complex, and the pyruvate dehydrogenase complex (PDC); all of which are enzymes utilized in metabolic pathways.
While the dihydrolipoamide dehydrogenase (DLDH) subunit of these complexes is derived from the same gene coding region (in most organisms), this paper deals with the activity of the PDC subunit. The Pyruvate Dehydrogenase Complex is an enzyme complex that catalizes the conversion of pyruvate to two molecules of acetyl CoA and thus connects the glycolitic pathway to the Krebs cycle, and is found in the inner mitochondrial space in eukaryotes.
Dihydrolipoamide dehydrogenase, or simply the E3 subunit, is the third enzyme of the Pyruvate Dehydrogenase Complex; and is responsible for the oxidation of lipoic acid, the product given by the E2 subunit (dihydrolipoyl transacetylase), and the reduction of NAD+. NAD+ and NADH effect the activity of the enzyme as an activator and inhibitor respectively.
The DLDH subunit itself consists of two monomers, each made of individual chains (click on the MDL insignia in the lower right hand corner of the interactive frame to stop the rotation of the enzyme).
chain A
chain B
Each chain of the DLDH subunit uses a bound FAD+