JUVENILE HORMONE ESTERASES IN TWO HELIOTHINES: KINETIC, BIOCHEMICAL AND IMMUNOGENIC CHARACTERIZATION

Juvenile hormone hydrolyzing activity in larval hemolymph of the tobacco budworm, Heliothis virescens, and the corn earworm, H. zea, was characterized by several biochemical approaches. 2. Evidence for enzyme differences between species came from using several alkylthiotrifluoropro- panones as selective inhibitors. 3. The enzyme purified by affinity chromatography from H. zea showed two bands on SDS-PAGE and two activity peaks on narrow range (pH 4-6.5) isoelectric focusing (IEF), while purified enzyme from H. virescens showed only one band on SDS-PAGE and one peak of activity on IEF. 4. ELISA tests using polyclonal antisera elicited by the purified enzyme from each species showed the enzyme from 1-1. virescens and H. zea to be antigenically distinct. 5. A kinetic analysis of enzyme from both species showed that the slow tight binding kinetics, often observed with inhibition by transition state analogs, were both compound and enzyme dependent.