Substrates for measuring the chymotryptic, PGPH, and tryptic acitivity of the 20S or 26S proteasome. See also the thrombin substrate I-1140.

The fluorogenic substrate Suc-LLVY-AMC is used for measuring the chymotrypsin-like activity of the 20S proteasome, in combination with e.g. Bz-VGR-AMC, I-1085 (for assaying its trypsin-like activity) and Z-LLE-AMC, I-1945 (for determining its PGPH activity). Suc-LLVY-AMC is also cleaved by a chymotrypsin-like enzyme from sperm extract of the ascidian Halocynthia roretzi, a strong inhibitor of fertilization. The substrate has also been used to analyze the chymotrypsin-like activity of trypsins as well as chymase from rat mast cells. Furthermore, Suc-LLVY-AMC is a substrate for carboxypeptidase Y, proteinase yscE (kexin), ingensin, as well as for porcine calpain isozymes I and II and for papain.