The PDE3A TR-FRET Assay Kit is designed to provide fast and easy identification of inhibitors of PDE3A (phosphodiesterase 3A) using Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET). The PDE3A TR-FRET Assay Kit comes in a convenient 96-well or 384-well format, with enough recombinant purified PDE3A (amino acids 669-end) enzyme, fluorescently labeled PDE substrate (cAMP), binding agent, and PDE assay buffer for 100 or 384 enzyme reactions.The reaction uses a fluorescein-conjugated (FAM) cyclic monophosphate nucleotide. Phosphodiesterase PDE3A catalyzes the hydrolysis of the phosphodiester bond in the cyclic monophosphate nucleotide, releasing the phosphate group for binding. The phosphate group binds to a "Binding Agent€ (BA) that is recognized by terbium-labeled donor beads. This results in energy transfer from the terbium to FAM, which emits a fluorescent signal at 520 nm. If unbound to the phosphate group, the terbium-labeled beads emit at λ=490 nm. The fluorescent intensity is measured using a fluorescence plate reader capable of TR-FRET reading and an increase in 520 nm corresponds directly to the activity of PDE3A.