The substrate specificity of cruzipain 2, a cysteine protease isoform from Trypanosoma cruzi.

Papain-like cysteine proteases are important for the survival of the flagellated protozoa Trypanosoma cruzi, the causative agent of Chagas' Disease. The lysosomal cysteine protease designated as cruzipain or cruzain, is the archetype of a multigene family of related isoforms. We investigated the substrate specificity of the cruzipain 2 isoform using internally quenched fluorogenic substrates. We found that cruzipain 2 and cruzain differ substantially regarding the specificity in the S2, S'1 and S'2 pockets. Our study indicates that cruzipain 2 has a more restricted specificity than cruzain, suggesting that these isoforms might act on distinct natural substrates.