REGULATION OF SPECIFIC ACTIVITY OF GLUCOSE-6-PHOSPHATE-DEHYDROGENASE AND 6-PHOSPHOGLUCONATE DEHYDROGENASE IN PENICILLIUM-CHRYSOGENUM

The specific activity of glucose-6-phosphate dehydrogenase and 6-phosp hogluconate dehydrogenase changed when Penicillium chrysogenum was gro wn on different carbon sources. In the presence of 2% lactose, the act ivities of these enzymes were approximately 25-35% lower than those in media containing 2% glucose or 2% fructose. We assume that an increas e in cAMP concentration was responsible for the observed decreases in the enzyme activities, because a higher cAMP concentration could be de tected when the mycelium was grown in a medium containing solely lacto se as carbon source. The likely role played by cAMP in the regulation was also demonstrated by the addition of either cAMP or caffeine to th e medium.