5-DTAF is a fluorescent probe that reactive with proteins. Unlike other reactive fluoresceins, 5-DTAF not only reacts with amino groups, but also reacts with thiol groups and even directly reacts with hydroxy groups such as polysaccharides and other alcohols in aqueous solution at pH above 9. Fluoresence: λex 495 nm, λem 516 nm; λex 492 nm, λem 514 nm in 0.1 M Tris pH 9.05-DTAF is a thiol-reactive label for proteins. 5-DTAF is a fluorescent probe that reactive with proteins. Unlike other reactive fluoresceins, 5-DTAF not only reacts with amino groups, but also reacts with thiol groups and even directly reacts with hydroxy groups such as polysaccharides and other alcohols in aqueous solution at pH above 9. Fluoresence: λex 495 nm, λem 516 nm; λex 492 nm, λem 514 nm in 0.1 M Tris pH 9.0 5-DTAF is a thiol-reactive label for proteins.