Fluorogenic substrate peptide of the 20S proteasome. In its intact state this peptide is non-fluorescent, however when Rhodamine fluorophore is released upon hydrolysation, fluorescence can be detected. This peptide is therefore a useful tool for analysing the activity of the 20S proteasome as well as other chymotrypsin-like proteases and calpains. This peptide is also a substrate for chymase, papain, carboxypeptidase Y, proteinase yscE (kexin) and ingensin.

The presence of the D-proline residue on the C terminal of the rhodamine molecule ensures one directional rhodamine cleavage which simplifies fluorescence studies. Rhodamine 110 is a laser grade fluorescent dye
with excitation maxima at 496 nm and emission maxima at 522 nm.