Highly purified Musca ecdysteroidogenin (ESG) was obtained by extracting housefly heads with an acid-ethanol-urea procedure followed by desalting on a Sephadex G25F column and fractionation on a Sephadex G50F column. Further fractionation was done on a semi-preparative C18 reverse-phase HPLC column with an acetonitrile gradient in 0.1% trifluoroacetic acid in water. Ecdysteroidogenic activity e...

1. The ATPase activity of insect mitochondria has been investigated. A comparison was made to determine the distribution and nature of such activity in other isolated fractions of the house fly, Musca domestica L. 2. The ATPase in insect mitochondria is specific in that orthophosphate can be cleaved only from ATP. The Michaelis-Menten constant K(8) = 2.78 x 10(-3)M and V(max.) = 76 micrograms P...