5(6)-FAM SE (full name: 5-(and-6)-Carboxyfluorescein, succinimidyl ester mixed isomers) is an amine-reactive green fluorescent dye widely used for labeling proteins or other molecules that contain a primary or secondary aliphatic amine. The coupling reaction is usually carried out at pH 8-9.5. The amide linkage from the coupling reaction is much more stable than the thiourea linkage formed from the coupling of an amine and an isothiocyanate.
