Calpain inhibitor XII is a reversible and selective inhibitor of calpain I (μ-calpain, Ki = 19 nM), with lower affinities for calpain II (m-calpain, Ki = 120 nM) and cathepsin B (Ki = 750 nM). Calpain inhibitors, including this compound, have been used to study the role of calpains in diverse processes, including neutrophil chemotaxis, neuronal signaling, and cardiac response to injury.
A cell-permeable dipeptidyl -ketoamide compound that acts as a potent, selective, reversible, and active site inhibitor of calpain-1
a series of new dipeptidyl alpha-keto amides of the general structure r1-l-leu-d,l-aa-conh-r2 including calpain inhibitor xii were synthesized and evaluated as inhibitors for the cysteine proteases calpain i, calpain ii, and cathepsin b. calpain ii was more sensitive to these inhibitors calpain inhibitor xii than calpain i. calpain i was also effectively inhibited by calpain inhibitor xii, but lower ki values than with calpain ii. cathepsin b was weakly inhibited by calpain inhibitor xii. the best calpain i inhibitor in this study was calpain inhibitor xii with ki value of 19 nm [1].
[1] li, z. ,ortega-vilain, a.c.,patil, g.s., et al. novel peptidyl α-keto amide inhibitors of calpains and other cysteine proteases. journal of medicinal chemistry 39(20), 4089-4098 (1996).
