Purity >98% (NMR, HPLC). Leupeptin hemisulfate is a reversible inhibitor of trypsin-like proteases and cysteine proteases. Inhibits trypsin, plasmin, papain and cathepsin B, H and L. Blocks various apoptotic pathways in T cells. Commonly used in cell lysis buffers to protect proteins from degradation. Typical working concentration is 1uM (0.5 ug/ml).