| Abstract: | Extracts of the mycelium of Coprinus lagopus (sensu Buller)contain two glutamate dehydro-genases with different optimumpH values. One is assayed with nicotinamide adenine dinucleotide(NAD-GDH) and the other with nicotinamide adenine dinucleotidephosphate (NADP-GDH). Changes in specific activity of the enzymeswere investigated during the growth of both a monokaryon (H9)and a dikaryon (H9 x TC) in different media and after the transferof mycelium from one growth medium into another. In the lattercase the magnitude of the changes in enzyme activity could bealtered by modification of either the carbon or the nitrogensource in the transfer medium. It is concluded from the resultsobtained that neither glutamate nor the ammonium ion seems toregulate directly the synthesis of either enzyme. However, someof the results are in accordance with the view that a productof glucose metabolism represses the synthesis of the NAD-GDHand derepresses or induces that of the NADP-CDH and evidencethat this regulator is 2-oxoglutarate was obtained. It is alsoconcluded that the complete system of regulation must involvemore than one molecule. |
