> Protein G Agarose

Protein G Resin is useful for affinity purification and isolation of IgG. Protein G, a bacterial cell wall protein isolated from Staphylococcus aureus, binds to mammalian IgGs mainly through Fc regions. Native Protein G has 3 IgG binding domains and also sites for albumin and cell-surface binding. Albumin and cell-surface binding domains have been eliminated from recombinant Protein G to reduce nonspecific binding. Additionally, 3×Cys tag was engineered to the C-terminal of rec-protein G to facilitate its immobilization. Although the tertiary structures of Protein A and Protein G are very similar, their amino acid compositions differ significantly, resulting in different binding characteristics. Protein G may be used for purification of mammalian monoclonal and polyclonal IgGs that do not bind well to Protein A. Protein G has greater affinity than Protein A for most mammalian IgGs, especially for certain subclasses including human IgG3, mouse IgG1 and rat IgG2a. Unlike Protein A, Protein G does not bind to human IgM, IgD and IgA.