PurKine™ Protein G Purification system is effective for affinity purification of IgG from serum and other fluids of many mammalian species. Protein G can 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. The portfolio allow optimization of process for maximum protein yield, stability and solubility. Tests also confirm that no decrease in performance occurs after at least five repeated uses. The PurKine™ Protein G Purification Resin is also available as prepacked spin column and kit formats.