Affinity of Protein A/G for IgG Types from Different Species

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  • Protein A and G are popular choices for antibody purification, because they are both stable and target selective. IgG class antibodies from multiple species bind to protein A and/or G, allowing antibody to be captured on protein-bound beads. Protein A and G bind IgG subtypes with varying affinities, determined by species and the properties of the heavy chain. Below is a chart that reports the affinity of protein A and G for various species immunoglobulin subtypes.
     

    Species Immunoglobulin Binding to Protein A Binding to Protein G
    Human lgG (normal) ++++ ++++
    lgG1 ++++ ++++
    lgG2 ++++ ++++
    lgG3 - ++++
    lgG4 ++++ ++++
    lgM - -
    lgA - -
    lgE - -
    Mouse lgG1 + ++++
    lgG2a ++++ ++++
    lgG2b +++ +++
    lgG3 ++ +++
    Rat lgG1 - +
    lgG2a - ++++
    lgG2b - ++
    lgG2c + ++
    Goat lgG +/- ++
    Rabbit lgG ++++ +++
    Sheep lgG +/- ++