E-64 is an inhibitor for thiol protease, papain, actinidin, ananain, bromelain, calpain and cathepsin B. An irreversible cysteine protease inhibitor that has no action on cysteine residues in other plants. It does not react with low molecular weight thiols such as 2-mercaptoethanol.

• Specific active site titrant
• Soluble in 50% acetic acid, water, or DMSO

It is an effective ligand for affinity purification of cysteine proteases. When coupled to a thiolated affinity matrix, binding is no longer irreversible, but specificity is retained.