抄録
An improved method for the preparation of the 2-oxoglutarate dehydrogenase complex from pig heart muscle that catalyzes CoA-and NAD^+-linked oxidative decarboxylation of 2-oxoglutarate. The highly purified complex has a sedimentation coefficient (s^0_20,W) of 35.7 S and a diffusion coefficient (D_<20>, w) of 1.18×10^<-7>cm^2/sec. 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. A highly purified preparation of the complex contained 6 moles of protein-bound TDP, 6 moles of bound lipoic acid and 9 moles of bound FAD per mole of the complex. This enzyme complex showed absolute dependence on added CoA and NAD^+ in the over-all reaction and showed partially dependence on added TDP in the 2-oxoglutarate dehydrogenase activity. The 2-oxoglutarate dehydrogenase activity of this enzyme complex was activated by Ca^<2+> than Mg^<2+>. Physicochemical data and enzymatic activities obtained in the present investigation are compared with those reported by Sanadi et al. and by Massey.
