MW: 263.26. Purity >99% by HPLC. Background: A synthetic peptide that irreversibly inhibits ICE-family protease/caspase activity and blocks apoptosis. The inhibitor is designed as a methyl ester to facilitate cell permeability. (CAUTION: If the intended use is on purified or recombinant enzymes, esterase should be added to generate free carboxyl groups).