Alpha-ketoglutarate dehydrogenase in the in vitro-grown Mycobacterium lepraemurium

The Hawaiian and Kumato strains of Mycobacterium lepraemurium were cultivated on Ogawa egg-yolk medium, and the alpha-ketoglutarate dehydrogenase activity was investigated in cell-free preparations of this mycobacterium. The enzymatic activity was mainly localized in the particulate fraction (150,000 x g pellet), and extremely low activity was found in the soluble fraction (150,000 x g supernatant). alpha-Ketoglutarate dehydrogenase was not stable; the activity was lost completely when the enzyme was kept at 45 degrees C for 1 hr or stored at -70 degrees C. The enzyme reduced only NAD+ but not NADP+ by alpha-ketoglutarate, indicating the presence of NAD(+)-dependent alpha-ketoglutarate dehydrogenase in cultivated M. lepraemurium.