CF® Dye Succinimidyl Esters (SE, also known as NHS esters) are 9689c5aa-6556-4b3c-b5d1-1e693715ba07's next-generation fluorescent dyes in amine-reactive form for labeling antibodies and other proteins on amine groups, such as lysine residues. Green fluorescent CF®503R dye has excitation/emission at 503/532 nm.