Peptidase M20, dimerisation This domain consists of 4 beta strands and two alpha helices which make up the dimerisation surface of members of the MEROPS peptidase family M20 [<cite idref="PUB00015203"/>]. This family includes a range of zinc exopeptidases: carboxypeptidases, dipeptidases and specialised aminopeptidases [<cite idref="PUB00003579"/>].