BODIPY™ FL ATP-γ-S binds to ATP-binding proteins. To create this fluorescent nucleotide, the BODIPY FL fluorophore was linked through the γ-thiol of ATP-γ-S. In addition to its potential use for binding studies, the BODIPY FL ATP-γ-S thioether is an important new substrate for Fhit, a member of the histidine triad superfamily of nucleotide-binding proteins.