Cathepsin B inhibitor. Competitive and reversible inhibitor of serine and cysteine proteinases like calpain, porcine kallikrein, trypsin, plasmin, papain and cathepsin B. Does not inhibit chymotrypsin and thrombin. Also known to inhibit activation-induced programmed cell death and restoration of defective immune responses of HIV+ donors. Alternative Name: Acetyl-L-leucyl-L-leucyl-L-argininal . hemisulfate. Formula: C20H38N6O4 . 0.5 H2SO4. MW: 426.6 . 49.0. CAS: 103476-89-7. MI: 14: 5456. Purity: ≥97% (HPLC). Appearance: White to off-white powder. Solubility: Soluble in water, methanol or 100% ethanol. Long Term Storage: -20°C. Handling: Protect from light and moisture.