Protein A is a 42kD polypeptide isolated from Staphylococcus aureus which has a specific binding affinity for the Fc region of IgG from several species. Each Protein A molecule has four IgG binding sites. In addition, protein A binds to IgG without interfering with the antigen binding site of the immunoglobulin. The Protein A coated magnetic particles provide a quick, easy, and economical way for the capture of antigen specific antibodies used in the purification of recombinant antigens.
In the past, protein A linked gel matrix has been routinely used for isolating IgG from human, mouse, and rabbit serum. However, protein A covalently bound to magnetic particles increases the reaction kinetics while reducing the capture time of antigen specific antibodies. As a result, Protein A coated magnetic particles are uniquely suited for isolating IgG from limited volume samples without dilution or loss. They can also be used to capture and concentrate low level IgG in large volume samples. In addition, Protein A coated magnetic particles can be repeatedly used without a significant loss in their ability to bind IgG.
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