Some Properties of Glutamic Dehydrogenase from Neurospora crassa

SUMMARY: A glutamic dehydrogenase from Neurospora requiring either DPNH or TPNH for activity has a pH optimum of 8·6 and is inhibited by a number of chelating agents. The specific activity of the enzyme was high during early growth, but it fell sharply from the 2nd to the 5th day after inoculation. A deficiency of Zn decreased enzyme activity and addition of the metal in vivo to Zn-deficient mycelial felts restored the enzyme to normal values after a few days of incubation. The enzyme was unchanged when pyridoxine or riboflavin was limiting in the growth of mutants which require these vitamins. With a purified enzyme the K m values in mole/1. were as follows: α-ketoglutarate 0·75 × 10−2; TPNH, 2 × 10−4; and DPNH, 2·3 × 10−4.