Peptide M / Agarose Peptide M is a 50 aa synthetic peptide derived from a streptococcal M protein containing an additional C-terminal cysteine residue. Peptide M binds monomeric and dimeric human IgA of both subclasses (IgA1 and IgA2) with high specificity and affinity. It also binds bovine IgA but not murine IgA. Peptide M binding occurs at a site in IgA-Fc conserved in human IgA1 and IgA2 and bovine IgA but not in mouse IgA. Peptide M can be used for single-step affinity purification of IgA and for specific detection of antigen-bound IgA. Binding capacity: 4 - 6 mg human IgA per ml of gel