A novel, stable, helical scaffold as an alternative binder - construction of phage display libraries.

Specific, high affinity binding macromolecules are of great importance for biomedical and biotechnological applications. The most popular classical antibody-based molecules have recently been challenged by alternative scaffolds with desirable biophysical properties. Phage display technology applied to such scaffolds allows generation of potent affinity reagents by in vitro selection. Here, we report identification and characterization of a novel helical polypeptide with advantageous biophysical properties as a template for construction of phage display libraries. A three-helix bundle structure, based on Measles virus phosphoprotein P shows a very favourable stability and solubility profile. We designed, constructed and characterized six different types of phage display libraries based on the proposed template. Their functional size of over 10(9) independent clones, balanced codon bias and decent display level are key parameters attesting to the quality and utility of the libraries. The new libraries are a promising tool for isolation of high affinity binders based on a small helical scaffold which could become a convenient alternative to antibodies.