AAT Bioquest's iFluor(TM) dyes are optimized for labeling proteins, in particular, antibodies. These dyes are bright, photostable and have minimal quenching on proteins. They can be well excited by the major laser lines of fluorescence instruments (e.g., 350, 405, 488, 555 and 633 nm). iFluor(TM) 680 dyes have fluorescence excitation and emission maxima of 680 nm and 700 nm respectively. These spectral characteristics make them an excellent alternative to Cy5.5(R) and Alexa Fluor(R) 680 labeling dyes (Cy5.5(R) and Alexa Fluor(R) are the trademark of Invitrogen and GE Health Care). iFluor(TM) 680 maleimide is reasonably stable and shows good reactivity and selectivity with thiol group.