The Transcreener® ADP2 Fluorescent Intensity (FI) Assay extends the Transcreener® platform for ADP detection by utilizing a simple fluorescent intensity output which can be used on both fluorescence readers typically found in academic and therapeutic research labs as well as more complex multimode plate readers more commonly used in core facilities and HTS labs. The Transcreener® ADP2 FI Assay is a red, competitive fluorescence intensity assay based on the detection of ADP and therefore is compatible with any enzyme class that produces ADP, including protein, lipid, and carbohydrate kinases, ATPases, DNA helicases, carboxylases and glutamine synthetase. It is a simple one step homogenous detection assay, and is flexible with regard to ATP concentration (0.1 to 100 µM ATP). The assay provides excellent signal at low substrate conversion, with a Z' ≥ 0.7 at 2.5% ATP conversion using 1 µM ATP.