BIOTIN BINDERS SELECTED FROM A RANDOM PEPTIDE LIBRARY EXPRESSED ON PHAGE

Recombinant biotin-binding phages were affinity-selected from a random peptide library expressed on the surface of filamentous phage. Phage binding to biotinylated proteins was half-maximally inhibited by micro molar concentrations of a monobiotinylated molecule. Sequencing of the peptide inserts of selected phages led to the identification of a pre viously unknown biotin-binding motif, CXWXPPF(K or R)XXC. A synthetic peptide containing this sequence motif inhibited streptavidin binding to biotinylated BSA with an IC50 of 50 muM. This compound represents t he shortest non-avidin biotin-binding peptide identified to date. Our results illustrate that phage display technology can be used to identi fy novel ligands for a small non-proteinaceous molecule.