Mammalian α-Keto Acid Dehydrogenase Complexes

An improved method for the preparation of 2-oxoglutarate dehydrogenase complex from pig heart muscle has been developed. This soluble complex was purified approximately 74-fold. The highly purified complex has a sedimentation coefficient (s20,w0) of 35.7 S and a diffusion coefficient (D20,w) of 1.18 x 10-7 cm2 sec-1. The molecular weight was calculated to be 2.8 million from sedimentation and diffusion coefficients and also to be 2.7 million from the data by the Archibald method. The complex contains thiamine pyrophosphate, protein-bound lipoic acid, and flavin adenine dinucleotide in the ratio of 1:1:1.5 and exhibits coenzyme A- and nicotinamide adenine dinucleotide-linked oxidative decarboxylation of 2-oxoglutarate.