Scintillating microtitration plates as platform for determination of [3H]estradiol binding constants for hER-HBD

A novel approach to direct determination of ligand binding constants for the human estrogen receptor hormone binding domain was developed. Recombinantly produced human receptor in yeast extracts was attached to scintillating microtitration plates. Radioligand binding to receptors was determined in a multi-detector scintillation counter designed for the microtitration plate format. The method was employed in equilibrium binding experiments, in binding competition tests and in determination of kinetic rate constants. The results obtained show that the methodology is valid in comparison to previously published data regarding hormone binding characteristics of estrogen receptors. Furthermore, the methodology offers several advantages over previous binding assays because the scintillating microtitration plates constitute both the binding reaction vial and the scintillant for the detection of bound radioactivity.