AFDye™ 488 is a water-soluble, highly photostable dye with a very high fluorescence quantum yield. AFDye™ 488 is green-emitting dye with excitation ideally suited for the 488 nm line. Its fluorescence is pH independent from pH 4 to pH 10.
AFDye™ 488 Acid (Alexa Fluor® 488 Acid equivalent) often used for the preparation of custom activated esters that often are not commercially available. Examples of such activated esters include sulfo-NHS, TFP (2,3,5,6-Tetrafluorophenol), and STP (4-Sulfo-2,3,5,6-Tetrafluorophenol, Sodium Salt). Another common application for the non-activated carboxylic acid is peptide modification during solid phase synthesis, which usually requires in-situ activation with peptide coupling regents, e.g. HATU.
AFDye™ 488 dye structurally is identical to Alexa Fluor® 488 dye.