Purity >95%. Ac-VDVAD-AFC is a fluorogenic substrate whose amino acids VDVAD have been shown to be a preferred cleavage site for caspase-2. 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. Increases in Ac-VDVAD-AFC cleavage have been reported to correlate with nitric oxide-induced activation of caspase-2 and subsequent apoptosis in human neuroblastoma lines.