 The DLD homodimer functions as the E3 component of the pyruvate, α-ketoglutarate, and branched-chain amino acid-dehydrogenase complexes and the glycine cleavage system, all in the mitochondrial matrix.In these complexes, DLD converts dihydrolipoic acid and NAD+ into lipoic acid and NADH.DLD also has diaphorase activity, being able to catalyze the oxidation of NADH to NAD+ by using different electron acceptors such as O2, labile ferric iron, nitric oxide, and ubiquinone.