Protein-A/G Cys

Protein A/G Cys Recombinant is composed of seven IgG-binding domains:

• Protein A: Derived from Staphylococcus aureus, it includes segments E, D, A, B, and C.
• Protein G: Derived from Streptococcus, it includes segments C1 and C3.

The recombinant protein is a single non-glycosylated polypeptide chain containing 430 amino acids and has a molecular mass of approximately 47.8 kDa . It is produced in Escherichia coli and is fused with a cysteine (Cys) at the C-terminus to facilitate its use in various applications.

Protein A/G Cys Recombinant has a broader binding capacity compared to individual Protein A or Protein G. It can bind to various human, mouse, and rat IgG subclasses, including:

• Human IgG1, IgG2, IgG3, IgG4
• Mouse IgG2a, IgG2b, IgG3
• Rat IgG2a, IgG2c

Additionally, it binds to total IgG from other species such as cow, goat, sheep, horse, rabbit, guinea pig, pig, dog, and cat .

The primary application of Protein A/G Cys Recombinant is in the purification of monoclonal or polyclonal IgG antibodies. Its broad binding capacity makes it ideal for use in various immunoassays, including:

• Immunoprecipitation
• Western blotting
• ELISA (Enzyme-Linked Immunosorbent Assay)

Protein A/G Cys Recombinant is typically provided as a sterile, lyophilized (freeze-dried) powder. For optimal stability, it should be stored desiccated below -18°C. Upon reconstitution, it can be stored at 4°C for short-term use (2-7 days) and below -18°C for long-term storage. To prevent degradation, it is recommended to avoid freeze-thaw cycles and to add a carrier protein (e.g., 0.1% HSA or BSA) for long-term storage .

The purity of Protein A/G Cys Recombinant is greater than 96%, as determined by HPLC and SDS-PAGE analysis . It is also tested for endotoxin levels, ensuring it is suitable for laboratory research use.