Recombinant Protein A

Staphylococcal Protein A, or SPA, is a type I membrane protein covalently linked to the cell wall of most strains of the Gram-positive bacterium Staphylococcus aureus. It has high affinity to IgG from various species, for instance human, rabbit and guinea pig but only weak interaction with bovine and mouse. Protein A interacts with antibodies through two distinct binding events: the “classical” binding site on the Fc portion of human IgG1, IgG2, and IgG4, and the “alternate” binding site found on the Fab portion of human IgG, IgM, IgA, and IgE that contain heavy chains of the VH3 subfamily. In addition, all native protein A domains show comparable Fab binding. The properties of protein A enables it as a powerful affinity ligand for several immunological and purification applications, is ideal for purification of polyclonal or monoclonal IgG antibodies. High selectivity and good physiochemical stability have made protein A the preferred generic ligand for affinity purification of antibodies and molecules tagged with an antibody Fc-region. Protein A can also be used in various immunochemical assays including Western blotting, immunohistochemistry, and ELISA applications by conjugation with different reporter molecules, such as fluorescent dyes (FITC), enzyme markers (peroxidase, β-galactosidase, alkaline phosphatase), biotin, and colloidal gold. Immunoprecipitation studies with protein A conjugated to beads are also commonly used to purify proteins or protein complexes indirectly through antibodies against the protein or protein complex of interest.

Store at ≤-70°C, stable for 6 months after receipt. Store at ≤-70°C, stable for 3 months under sterile conditions after opening. Please minimize freeze-thaw cycles and use a manual defrost freezer.