Specificity of calcium-activated neutral proteinase (CANP) inhibitors for human μCANP and mCANP.

We investigated the relative inhibition of purified human μCANP and mCANP by five cysteine proteinase inhibitors including N-acetyl-Leu-Leu-nor-leucinal (C-I) and N-acetyl-Leu-Leu-methioninal (C-II), calpeptin, E64, and leupeptin. Based on IC measurements, calpeptin and C-I were stronger inhibitors by one to two orders of magnitude than C-II, leupeptin or E64. None of the five inhibitors, however, exhibited greater specificity for human μCANP or mCANP. These results indicate that, although the inhibition of a given cellular event by these compounds may suggest CANP involvement, effects on μCANP cannot be discriminated from those on mCANP. [ABSTRACT FROM AUTHOR]