Protein A G Binding Affinity

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Relative binding strengths of antibodies from various species to protein G and protein A as measured in a competitive ELISA test. The amount of IgG required to give a 50% inhibition of binding of rabbit IgG conjugated with alkaline phosphatase was determined.

Species Subclass Protein G binding Protein A binding
Human IgA

IgD

IgE

IgG1

IgG2

IgG3

IgG4

IgM*
–

–

–

++++

++++

++++

++++

–
variable

–

–

++++

++++

–

++++

variable
Avian egg yolk IgY† – –
Cow   ++++ ++
Dog   + ++
Goat   ++ –
Guinea pig IgG1 ++ ++++
Hamster   ++ +
Horse   ++++ ++
Koala   + –
Llama   + –
Monkey (rhesus)   ++++ ++++
Mouse IgG1

IgG2a

IgG2

IgG3

IgM*
++++

++++

+++

+++

–
+

++++

+++

++

variable
Pig   +++ +++
Rabbit   +++ ++++
Rat IgG1

IgG2a

IgG2

IgG3
+

++++

++

++
–

–

–

+
Sheep   ++ +/–
  • Purified using HiTrap IgM Purification HP columns.
    † Purified using HiTrap IgY Purification HP columns.
    ++++ = strong binding.
    ++ = medium binding.
    — = weak or no binding.