Members of this family are asparaginyl peptidases. The blood fluke parasite Schistosoma mansoni has at least five Clan CA cysteine peptidases in its digestive tract including cathepsins B (2 isoforms), C, F and L. All have been recombinantly expressed as active enzymes, albeit in various stages of activation. In addition, a Clan CD peptidase, termed asparaginyl endopeptidase or 'legumain' has been identified. This has formerly been characterized as a 'haemoglobinase', but this term is probably incorrect. Two cDNAs have been described for Schistosoma mansoni legumain; one encodes an active enzyme whereas the active site cysteine residue encoded by the second cDNA is substituted by an asparagine residue. Both forms have been recombinantly expressed.