Photoaffinity labels for insect juvenile hormone binding proteins: Synthesis and evaluation in vitro

Abstract

The interactions of insect juvenile hormones (JH) with proteins are critically important to titer regulation, transport, and hormone action at a molecular level. We have synthesized several JH analogs bearing photolabile diazocarbonyl groups as potential photoaffinity labels for JH binding proteins (JHBP). The most promising compound, 10, 11-epoxyfarnesyl diazoacetate ( 2) (EFDA) competes with JH III for The JH binding site of JHBP from Leucophaea hemolymph and ovaries and from cultured Drosophila cells. Moreover, irradiation of protein solutions containing micromolar amounts of EFDA gave irreversible loss of [ 3H]-JH III binding capacity with no change in binding affinity of the unlabelled protein. The protein could be protected against photoinactivation by the presence of equimolar JH III during irradiation. High specific activity [10- 3H]-EFDA was prepared and used to demonstrate specific, finite binding of EFDA to the JH III receptor site of the binding protein. Further applications of photoaffinity labelling technique to characterization and cellular localization of the JHBP are discussed.