Hydrolyzes chromogenic peptides at the carboxyl Arg or Lys; requires at least one more amino acid, preferably Arg, Phe, Val or Leu, between the terminal Arg or Lys and the amino-blocking group. The cysteine protease may play an important role in the development and differentiation of the parasites at several stages of their life cycle. Broad endopeptidase specificity similar to that of cathepsin L. Strongly inhibited by E-64 (L-trans-epoxysuccinylleucylamido(4-guanidino)butane), Leupeptin, and N-alpha-p-tosyl-L-lysine chloromethyl ketone. Present in all developmental stages. Purified cruzipain is able to degrade itself, yielding a complex mixture of small peptides, and a major 25 kDa fragment. Belongs to the peptidase C1 family.