Protein A Agarose Resin: Protein A agarose (cat. No. BSP096, BSP095) is useful for affinity purification and isolation of IgG. Protein A, a bacterial cell wall protein isolated from Staphylococcus aureus, binds to mammalian IgGs, mainly through Fc regions. Native protein A has five IgG binding domains and many other domains of unknown functions. Recombinant protein A contains mainly five high affinity (Ka=108/M) IgG binding domains with other non-essential domains removed to reduce nonspecific binding. Protein A agarose has been used to isolated 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 antigens. These qualities of protein A agarose combined with BioBasic Inc.’s precision and affordability make Protein A agarose ideal for the isolation of protein complexes by immunoprecipitation