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Binding comparison between Protein A, Protein G, Protein A/G and Protein L

Protein A, Protein G, Protein A/G and Protein L 


Protein A, Protein G, Protein A/G and Protein L are native and microbial recombinant proteins which have binding sites for the Fc portion of mammalian IgGs. The capacity of these proteins for IgG varies with the species. The interaction between the various proteins and IgG is not equivalent for all species or all antibody subclasses. In general, IgGs have a higher affinity for Protein G than for Protein A, and Protein G can bind IgG from a wider variety of species. The affinity of various IgG subclasses, especially from mouse and human, for Protein A varies more than for Protein G. Protein A can, therefore, be used to prepare isotypically pure IgG from some species. Protein L has an affinity for kappa light chains from various species. It can be used to purify monoclonal or polyclonal IgG, IgA, and IgM as well as Fab, F(ab1)2, and recombinant scFv fragments that contain kappa light chains.


The table below will help you decide which affinity support is best for your application.

Species Antibody Class Protein A Protein G Protein A/G Protein L*
Human Total IgG S S S S
  IgG1, IgG2 S S S S
IgG3 W S S S
IgG4 S S S S
IgM W NB W S
IgD NB NB NB S
IgA W NB W S
IgA1, IgA2 W NB W S
IgE M NB M S
Fab W W W S
ScFv W NB W S
Mouse Total IgG S S S S
  IgM NB NB NB S
IgG1 W M M S
IgG2a, IgG2b, IgG3 S S S S
Rat Total IgG W M M S
  IgG1 W M M S
IgG2a NB S S S
IgG2b NB W W S
IgG2c S S S S
Cow Total IgG W S S NB
  IgG1 W S S NB
IgG2 S S S NB
Goat Total IgG W S S NB
  IgG1 W S S NB
IgG2 S S S NB
Sheep Total IgG W S S NB
  IgG1 W S S NB
IgG2 S S S NB
Horse Total IgG W S S -
  IgG(ab), IgG(c) W NB W -
IgG(T) NB S S -
Rabbit Total IgG S S S W
Guinea Pig Total IgG S W S -
Hamster Total IgG M M M S
Pig Total IgG S W S S
Donkey Total IgG M S S -
Cat Total IgG S W S -
Dog Total IgG S W S -
Monkey Total IgG S S S -
Chicken Total IgY NB NB NB NB
W = weak binding, M = medium binding, S = strong binding, NB = no binding, - means information not available.

* Binding will only occur if the appropriate kappa light chains are present. The binding affinity only refers to species and subclasses with the correct kappa light chains. Lambda light chains and some kappa light chains will not bind.