AC-YVAD-PNA

N-Acetyl-L-tyrosyl-L-valyl-L-alanyl-N-(4-nitrophenyl)-L-α-asparagine is a substrate whose amino acids YVAD have been shown to be a preferred cleavage site for caspase-1 and -4.

Ac-YVAD-pNA is a very selective chromogenic substrate for caspase-1, a key mediator of inflammatory processes formerly known as interleukin (IL)-1-converting enzyme. Ac-YVAD-pNA is used to determine caspase-1 activity. Cleavage of Ac-YVAD-pNA by caspase-1 releases pNA (p-nitroanilide), which can be quantified spectrophotometrically at 405 nm.