Fluorescent Peptides/Protein Substrates – SUC-LLVY-AMC (UBPBio catalog# G1100, G1101) – Suc-LLVY-AMC is a fluorogenic substrate for the chymotrypsin – like activity of the 20S and 26S proteasomes. Working concentrations of this substrate is 50-200 µM. The released AMC can be detected by a fluorimeter or plate reader at excitation/emission wavelengths of 380 nm/460 nm, respectively. When used to determine proteasome activity in cell lysates, cell lysates that are pre-treated with a proteasome inhibitor such as MG132, PS341 or epoxomicin can be used to determine the fluorescence contributed by other cellular proteases that cleave this substrate. Readings from proteasome inhibitor-treated lysates should be subtracted.