Leishmania (L.) amazonensis peptidase activities inside the living cells and in their lysates

► Leishmania amastigotes incorporate only peptides containing positively charged amino acids. ► Leishmania express cysteine peptidases adapted to different environments. ► Oligopeptidase B was detected in vivo inside the amastigotes. ► FRET peptide Abz-AGRRRAQ-EDDnp characteristically identify oligopeptidases B.