ECDYSONE INACTIVATION IN BLOW-FLIES CALLIPHORA ERYTHROCEPHALA MEIGEN

Ecdysone is rapidly inactivated in vivo. Two hours after injection, only 20 per cent of the hormone could be recovered. The inactivation is mediated by an enzyme system which is present in the fat body. Within the cells, it is located in the 'cytosol' since it can be extracted by buffer solution and is found in the supernatant of 100,000 g centrifugation. The enzyme can be purified by ammonium sulphate precipitation. The activity of this enzyme system was measured in different stages of development. It was found that the activity of the inactivating enzyme is nearly a mirror image of the ecdysone titre as measured by Shaaya and Karlson. © 1969.