Affibody molecule

Affibody Molecule is a type of small, robust protein engineered to bind to a wide range of target proteins with high affinity. These molecules are derived from the B-domain of the Staphylococcus aureus protein A, and have been used in various applications in life science research, diagnostics, and therapy.

History

Affibody molecules were first developed in the 1990s by researchers at the Royal Institute of Technology in Stockholm, Sweden. The goal was to create a protein-based binding molecule that was smaller and more stable than antibodies, the traditional protein binders used in many biological applications.

Structure and Function

Affibody molecules are composed of a three-helix bundle, with each helix containing 13-14 amino acids. The binding surface of the molecule is formed by 13 amino acids on the first and second helices, which can be varied to create a high-affinity binder for a specific target protein.

The small size of Affibody molecules (58 amino acids, compared to about 1,300 for an antibody) allows them to penetrate tissues more effectively and bind to their targets more quickly. They are also more stable and less likely to be degraded by proteases, making them useful for applications in harsh environments.

Applications

Affibody molecules have been used in a wide range of applications, including:

• Protein Purification: Affibody molecules can be used to purify target proteins from complex mixtures, similar to the use of antibodies in immunoprecipitation.
• Therapeutics: Affibody molecules can be engineered to bind to disease-related proteins, potentially blocking their activity and treating the disease. For example, Affibody molecules have been developed to bind to HER2, a protein overexpressed in some types of breast cancer.
• Imaging: Affibody molecules can be labeled with radioactive isotopes and used to image the distribution of target proteins in the body, a technique known as molecular imaging.

Future Directions

Research is ongoing to further improve the properties of Affibody molecules and expand their range of applications. This includes efforts to increase their stability, improve their binding affinity, and develop new methods for their production and purification.