Protein G beads

Protein G is an immunoglobulin-binding protein expressed by C-type or G-type Streptococcal bacteria, which specifically binds to the Fc region of mammalian immunoglobulins (Ig). This product is a modified recombinant Protein G (25 kDa) covalently coupled to 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 G beads can specifically bind to corresponding antibodies, such as human IgG1, IgG2, IgG3, IgG4, mouse IgG1, IgG2a, IgG2b, IgG3, rat IgG1, IgG2a, IgG2b, IgG2c, and rabbit and goat polyclonal antibodies, etc. Each Protein G molecule can bind to three IgG molecules. It is mainly used for immunoprecipitation (IP), co-immunoprecipitation (Co-IP), or chromatin immunoprecipitation (Ch-IP), as well as 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 table below (Table 1).

This product offers multiple significant advantages in use. Firstly, it can achieve a high content of bound antibodies along with high binding specificity. Compared with traditional Protein G agarose gel, this product has smaller pore size, less non-specific adsorption, and a higher binding capacity. 1 ml of Protein G beads suspension contains approximately 10 mg of magnetic beads and no less than 0.6 mg of recombinant Protein G. Each recombinant Protein G contains three 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 the target protein, etc. During experiments, typically 500 μl of sample can be used with 10-20 μl of Protein G beads suspension to conduct efficient immunoprecipitation experiments. Secondly, it enables ultra-fast binding of antibodies or antibody complexes. Protein G 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 operations, fully ensuring the activity of the target protein. Due to the magnetic separation method, 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)