Protein A binds to the Fc region of immunoglobulins through interactions with the heavy chain.

• For affinity chromatography
• For immunoglobin purification and fractionation, immunoprecipitation procedures and polyclonal antibody purification
• Strong binding to Fc region of IgG
• High capacity - 20 mg human IgG/ml
• Cyanogen bromide activation coupling method
• Stable in all commonly used aqueous buffers, 6 M guanidine-HCl, 8 M urea
• Freeze-dried powder or preswollen in 20% ethanol
• Negligible volume variation due to changes in pH or ionic strength

The binding of protein A has been well documented for IgG from a variety of mammalian species and for some IgM and IgA as well. Protein A Sepharose CL-4B has been used as a powerful tool to isolate and purify classes, subclasses and fragments of immunoglobulins from biological fluids and from cell culture media. Since only the Fc region is involved in binding, the Fab region is available for binding antigen.