Technical Tips: Protein A and Protein G PLUS
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1. What is protein A? Top
Protein A is derived from Staph A (Staphylococcus aureus).
2. What Classes of Immunoglobulins does protein A bind? Top
It binds the Fc region of immunoglobulins. It binds with high affinity to human IgG1 and IgG2 as well as mouse IgG2a and IgG2b. Protein A binds with moderate affinity to human IgM, IgA and IgE as well as mouse IgG1. It does not react with human IgG3 or IgD, nor will it react to mouse IgG3, IgM, IgA or IgE.
3. What is Protein G PLUS? Top
Protein G PLUS is a genetically engineered form of streptococcal Protein G that has an increased capacity and has had the albumin binding site removed to reduce background.
4. What classes of Immunoglobulins does protein G PLUS bind? Top
It is specific for IgGs, binding with high affinity to human IgG1, IgG2 and IgG3 as well as mouse IgG1 and IgG3. Protein G PLUS has moderate affinity for human IgG4 and mouse IgG2a and IgG2b, and does not react significantly with mouse or human IgA, IgD, IgE, IgM or albumin.
5. How do I use protein A or G? Top
For antibody purification, the majority of the Ig should elute with buffer A. To maximize purity, use only the buffer A eluate. To maximize yield, combine the eluate from buffers A and B. You can also try coating the Protein A/G PLUS with BSA to reduce nonspecific binding, but you will get BSA eluting with the Ig.
6. What is the formulation of protein A and/or G? Top
Our Protein A and/or G PLUS beads for immunoprecipitation (Cat# IP02, IP04 and IP05) come precoated with BSA.
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