Affibody has created a large library consisting of approximately three billion Affibody® molecules, from which binders to given targets are selected. Affibody® molecules can be produced using either recombinant bacteria or peptide synthesis.

Key features of Affibody® molecules include:

• Robustness
• Small size
• Specific target recognition
• Efficient and spontaneous folding
• Rapid clearance from the body

The current library of billions of Affibody® molecules, all with unique binding sites and capable of binding different target proteins, has been created by randomization of 13 amino acid residues yielding a whole new surface on one side of the small protein domain. The common backbone of Affibody® molecules is a compact three-helix bundle domain.

The exceptionally stable Affibody® molecules display reversible and rapid folding and favorable target binding properties. Affibody® molecules are also very easy to modify and couple into fusion proteins. Bi-specific binders are readily made by combining two molecules with different specificity. The engineering flexibility enables tailor-making Affibody® molecules for different applications.