Leupeptin is a reversible inhibitor of trypsin-like proteases and cysteine proteases, including trypsin, plasmin, papain, cathepsin B, H and L1-3. Leupeptin also blocks various apoptotic pathways in T cells and can inhibit activation-induced programmed cell death. Leupeptin is widely used in cell lysis buffers to protect proteins from degradation, at a typical working concentration of 1 µM (0.5 µg/mL).
