The effect of incorporating α, α′-diethylglycine and α-aminocyclopentane carboxylic acid at the P2 position of inhibitors on μ-calpain inhibition was studied. Compound 3 with α, α′- diethylglycine was over 20-fold more potent than 2 with α-aminocyclopentane carboxylic acid. Additionally, 3 was over 35-fold selective for μ-calpain compared to cathepsin B, while 2 was 3-fold selective for cathepsin B compared to μ-calpain. Thus, the conformation ...
