Purity >95%. Ac-IETD-AFC is a fluorogenic substrate that can be cleaved by caspase-8 and related enzymes that recognize the amino acid sequence IETD, including caspase-3 processing enzyme, caspase-10, and granzyme B. Caspase activity can be quantified by fluorescent detection of free AFC (also known as 7-amino-4-trifluoromethylcoumarin), which is excited at 400 nm and emits at 505 nm.