[摘要]：Calpain 10 has been localized to the mitochondria and is a key mediator of Ca2+ induced mitochondrial dysfunction. A peptide screen followed by a series of modifications identified the homodisulfide form of CYGAK2 as an inhibitor of calpain 10 while showing no inhibitory activity against calpain 1. Methylation or truncation of the N-terminal cysteine significantly reduced the inhibitory activity of (CYGAK)2 and inhibition was reversed by reducing agents, suggesting that CYGAK forms a disulfide with a cysteine near the active site. Data suggest CYGAK may be a P' calpain inhibitor and may achieve its specificity through this mechanism. CYGAK inhibited calpain activity in intact mitochondria, renal cells, and hepatocytes, prevented Ca2+ induced cleavage of NDUFV2, and blocked Ca2+ induced state III dysfunction. CYGAK2 is the first P' specific calpain inhibitor and will be a valuable tool to prevent Ca2+ induced mitochondrial dysfunction and explore the function of calpain 10.
