Protein A beads

Protein A is a cell wall surface protein discovered in Staphylococcus aureus, with a molecular weight of 42 kDa. It can specifically bind to the Fc region of mammalian immunoglobulin (Immunoglobulin, Ig) and also binds to the Fab region of the human VH3 family. This product is a modified recombinant Protein A (25 kDa) covalently coupled with nano-scale amino magnetic beads. It retains only the amino acid sequences related to the binding of the Fc end of IgG, etc., and removes the sequences outside the binding sites that may cause non-specific binding, thereby effectively reducing non-specific binding.

Protein A beads can specifically bind to corresponding antibodies, such as human IgG1, IgG2, IgG4, mouse IgG2a, IgG2b and rabbit IgG, etc. Each Protein A molecule can bind to five IgG molecules. They are mainly used in immunoprecipitation (IP), co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (Ch-IP), and the purification of antibodies from samples such as serum, cell culture supernatants or ascites. The binding capacity for common immunoglobulin subclasses and the total binding capacity for different species are shown in the following table (Table 1).

This product offers multiple significant advantages in use. Firstly, it enables high content and specific binding of antibodies. Compared with traditional Protein A agarose gel, this product has smaller pore size, less non-specific adsorption, and higher binding capacity. 1 ml of magnetic bead suspension contains approximately 10 mg of magnetic beads and no less than 0.6 mg of recombinant Protein A. Each recombinant Protein A contains five Fc binding domains and can bind no less than 0.7 mg of Human IgG. The specific maximum binding capacity is related to the type of antibody and target protein, etc. In experiments, typically 500 μl of sample can be used with 10-20 μl of Protein A beads suspension to conduct efficient immunoprecipitation experiments. Secondly, it allows for ultra-fast binding of antibodies or antibody complexes. Protein A beads (~200 nm) have a large specific surface area, facilitating rapid and effective binding of magnetic beads with antibodies or antibody complexes. Usually, the adsorption process of antibodies or their complexes can be completed within 10 minutes, and the immunoprecipitation operation of the target protein can be completed within 30 minutes. Shortening the operation time can effectively prevent the degradation or denaturation of the target protein during long-term operation, fully ensuring the activity of the target protein. Due to the use of magnetic separation, each IP and Co-IP operation can save 40% of time compared with agarose gel. Finally, various methods can be used for elution. Based on the structure, biological function, and design requirements of subsequent applications of the target protein, acidic solutions, SDS-PAGE loading buffer, or competitive peptides and other elution solutions can be used for elution. (Specific product parameters are shown in Table 2)