Adult and juvenile Fasciola cathepsin L proteases: Different enzymes for different roles

► Temporally expressed Fasciola cathepsin Ls possess diverse characteristics. ► The amino acid at position 69 is important for the S2 subsite architecture. ► The amino acid at position 69 can influence substrate specificity. ► FgCatL1G can cleave substrates with proline residues at P2. ► Apparent orthologs between the two Fasciola species have functional differences.