Fluorescein (DTAF)
Amax: 492
Emax: 520nm
DTAF (Dichlorotriazinylamino fluorescein) is another form of fluorescein, with excitation and emission peaks identical to those of FITC. We use DTAF (instead of FITC) only for conjugation with streptavidin, since fluorescence from FITC is greatly quenched after conjugation with streptavidin. This phenomenon is unique to streptavidin, and is not observed with antibodies.