AFDye™ 555 Maleimide is a water-soluble, bright orange-fluorescent dye with excitation ideally suited for the 532 nm or 555 nm laser lines and visualized with TRITC (tetramethylrhodamine) filter sets. AFDye™ 555 conjugates of antibodies, peptides, and proteins are pH insensitive from pH 4 to pH 10. Proteins can be labeled with AFDye™ 555 dye at high molar ratios without significant self-quenching, leading to brighter conjugates and more sensitive detection. AF 555 conjugates ideally suited for detection of low abundance targets.
Maleimide is the most popular sulfhydryl-reactive reactive group for conjugating the dye to a thiol group on a protein, oligonucleotide thiophosphate, or low molecular weight ligand. The maleimide group specifically and efficiently reacts with reduced thiols (sulfhydryl groups, –SH) at pH 6.5 to 7.5 to form stable thioether bond. The resulting conjugates exhibit brighter fluorescence and greater photostability than the conjugates of many other spectrally similar fluorophores.
AFDye™ 555 is spectrally is almost identical to Cy3 Dye, Alexa Fluor® 555, CF® 555 Dye, or any other Cyanine3 based fluorescent dyes.