Transcreener Assays utilize homogenous immunodetection of nucleotides to provide robust, generic detection of entire families of drug targets. The competitive, time-resolved fluorescence resonance energy transfer (TR-FRET) immunoassay, for the detection of ADP, relies on a monoclonal antibody that selectively differentiates ADP from ATP. The assay can be used for any enzyme class that produces ADP, including protein, lipid or carbohydrate kinases, ATPases, DNA helicases, and carboxyltransferases. The “mix and read” product offers an excellent signal at low ATP conversion resulting in overall Z’> 0.6. The assay can accommodate from 1 µM to 100 µM ATP.