CALPAIN INHIBITOR I

Calpain Inhibitor I is an inhibitor of Calpain 1(calpain I) (K_i = 190 nM), Calpain 2(calpain II) (K_i = 220 nM), cathepsin B (K_i = 150 nM), and cathepsin L (K_i = 500 pM). It inhibits neutral cysteine proteases and proteasome (K_i = 6 μM). It inhibits apoptosis in thymocytes and metamyelocytes. It also inhibits cell cycle progression at the G1/S border and metaphase/anaphase in CHO cells by inhibiting cyclin B degradation. Calpain Inhibitor I inhibits the proteolysis of IκBα and IκBβ by the ubiquitin-proteasome complex. Furthermore, it protects against neuronal damage caused by hypoxia and ischemia. Calpain Inhibitor I also prevents nitric oxide production by activated macrophages by interfering with transcription of the inducible nitric oxide synthase gene.