AFDye™ 488 TFP Ester (sold under Alexa Fluor® 488 TFP Ester name) is an amine reactive, green emitting dye routinely used to label proteins or antibodies through the primary amines (Lys), amine-modified oligonucleotides, and other amine-containing biomolecules. The labeling occurs most efficiently at pH 7-9 and forms a stable, covalent amide bond. AFDye™ 488 dye conjugates are highly photostable dye with very high fluorescence quantum yield, and its green fluorescence is pH independent from pH 4 to pH 10.
TFP (tetrafluorophenyl) ester is an amine-reactive activated ester that reacts with primary amines of biomolecules in the same way as the succinimidyl ester (SE or NHS-ester) to form a stable amide bond. The major advantage of TFP esters over the succinimidyl ester is much improved resistance to spontaneous hydrolysis during conjugation reactions resulting in more efficiency and better reproducible labeling of biopolymers. TFP esters are stable for several hours at the basic pH typically used for reactions–far outlasting succinimidyl esters..
AFDye™ 488 dye structurally is identical to Invitrogen’s Alexa Fluor® 488