THE NAD-DEPENDENT GLUTAMATE-DEHYDROGENASE FROM DICTYOSTELIUM-DISCOIDEUM - PURIFICATION AND PROPERTIES

The NAD-dependent glutamate dehydrogenase (GDH) from Dictyostelium discoideum was purified 1101-fold with a yield of 23.4%. The enzyme has an apparent Mr of 356 kDa, determined using Sephacryl S400, and a subunit molecular weight of 54 kDa on SDS-polyacrylamide gel electrophoresis. The Kms for α-ketoglutarate, NADH, and NH4+ are 0.36 ± 0.03 mm, 16.0 ±0.1 μm, and 34.5 ± 2.7 mm, respectively. The purified enzyme has a pH optimum of pH 7.25-7.5. At 0.1 mm, ADP and AMP stimulate GDH activity 25 and 102%, respectively. Halfmaximal activity in the presence of 0.1 mm AMP for α-ketoglutarate, NADH, and NH4+ is reached at 2.3 ± 0.1 mm, 71.4 ± 5.5 μm, and 27.9 ± 3.6 mm, respectively. © 1991.