Fluorescein (6-FAM) is covalently conjugated on anti-DYKDDDDK mouse mAb (clone : FG4R) and purified by gel filtration. Usually, the molar ratio of fluorescein to antibody is at the range of 3-10. In TR-FRET assays, a typical concentration of fluorescein labeled antibody is at 0.8 - 1.2-fold of the concentration of the target protein. User should optimize the assay to achieve a desirable signal-to-background ratio, including the concentration and ratio of fluorescein or terbium labeled antibody, IgG or proteins corresponding to your specific assay design.
