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Affibody® Molecules - what are they?
Affibody® affinity ligands are unique research reagents, produced using innovative protein-engineering technologies. They are small, simple proteins composed of a three-helix bundle based on the scaffold of one of the IgG-binding domains of Protein A. Protein A is a surface protein from the bacterium Staphylococcus aureus. This scaffold has excellent features as an affinity ligand and can be designed to bind with high affinity to any given target protein. The domain consists of 58 amino acids, 13 of which are randomized to generate Affibody® libraries with a large number of ligand variants. Thus, the libraries consist of a multitude of protein ligands with an identical backbone and variable surface-binding properties.
Why use Affibody® Molecules?
In function, Affibody® Molecules mimic monoclonal antibodies. Compared to antibodies, the most striking dissimilarity of Affibody® Molecules is the small size. Affibody® Molecules have a molecular weight of 6kDa, compared to the molecular weight of antibodies, which is 150kDa. In spite of its small size, the binding site of Affibody® Molecules is similar to that of an antibody.
The advantages of Affibody® Molecules over antibodies are:
-their small size
-the simple structure of the molecules
-its robust physical properties; able to withstand a broad range of analytical conditions, including extreme pH and elevated temperature
-its ability to fold correctly intracellularly
-Conjugation or directed coupling to matrices are facilitated by the unique C-terminal cysteine.
Affibody® Molecules have highly competitive properties for applications within affinity purification, sample preparation and protein detection.
ICC / IF - Anti-ErbB2 Affibody® Molecule (Biotin) (ab31890)
Cells of the human mammary gland cell line SK-BR3 were stained with biotin conjugated Anti-ErbB2 Affibody® molecule (ab31890). The staining was localized to the membrane of the ErbB2 expressing human mammary gland cells. Nuclei were counter stained with DAPI (blue fluorescence).
The SK-BR3 cells were stained for 30 minutes at a concentration of 1-5ug Affibody® molecule/ml.