Blue emitting Coumarin 343 dye can form a FRET pair with fluorescein (FAM). An amine reactive form, activated NHS ester.
This amine-reactive NHS ester contains an aminohexanoyl linker between the fluorophore, and the reactive group. This linker provides better solubility and spatial separation between the fluorophore, and the target molecule being labeled.
This reagent can be used to design FRET based assays with FAM as acceptor, and to construct systems which harvest blue light energy.