Ki: 19 nM for μ-calpain
Calpain Inhibitor XII is a reversible and selective inhibitor of calpain I.
Calpain is a protein belonging to the family of calcium-dependent, non-lysosomal cysteine proteases expressed ubiquitously in mammals and many other organisms. Calpain inhibitors have been used to study the role of calpains in diverse processes, including neutrophil chemotaxis, neuronal signaling, and cardiac response to injury.
In vitro: 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].
In vivo: Up to now, there is no animal in vivo data reported.
Clinical trial: So far, no clinical study has been conducted.
Reference:
[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).