Full text loading...
Abstract
The NAD-dependent glutamate dehydrogenase from Phycomyces spores was purified more than 300-fold. Estimation of M r by gel filtration gave a value of 98000 whereas after SDS-PAGE one major band of M r 54000 was found, suggesting that the enzyme is a dimer. The enzyme was virtually dependent on the presence of AMP for activity and showed half-maximal activation at 9·5 and 43 μm-AMP in the direction of amination and deamination respectively. ADP was nearly as effective at 20-fold higher concentrations. Other nucleotide monophosphates were ineffective and nucleoside triphosphates were slightly inhibitory. Hyperbolic kinetics were found for all substrates yielding K m values of about 10 mm for ammonium, 1 mm for 2-oxoglutarate and 0·1 mm for NADH in the direction of amination, and 10 mm for glutamate and 0·7 mm for NAD in the direction of deamination.
- Received:
- Revised:
- Published Online: