AFDye™ 568 TFP Ester (Alexa Fluor 568 TFP Ester equivalent) is an amine-reactive, orange fluorescent dye routinely used to label proteins or antibodies through the primary amines (Lys), amine-modified oligonucleotides, and other amine-containing biomolecules. AFDye™ 568 dye can be used for proteins labeling at high molar ratios without significant self-quenching, enabling brighter conjugates and more sensitive detection.
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™ 568 is structurally identical to Alexa Fluor® 568 sold by ThermoFisher Scientific.