Investigation of the binding selectivity of a Drosophila pheromone-binding protein

The well-known problem of measuring the binding between water insoluble ligands and proteins is addressed in this study. The solution we proposed involves the use of â-cyclodextrin as a solubilizer and mediator. By applying this method to Drosophila pheromone-binding protein LUSH that binds to the pheromone 11-cis vaccenyl acetate (cVA), we demonstrated that this approach could successfully obtain thermodynamically valid dissociation constants. The ligand-induced, concentration dependent quenching of Trp 123 fluorescence in LUSH was used to measure the binding. By demonstrating that LUSH can bind to the silkmoth pheromone bombykol, we took one step further towards proving that pheromone-binding proteins are not uniquely selective towards their ligands.