Antibody as a surrogate receptor in the screening of a phage display library

Polyclonal antibody (Ab) against biotin (anti-biotin Ab) was evaluated as a source of shape mimics for the biotin-binding pocket of streptavidin (Sv). A 6-mer phage display library was panned with anti-biotin and the selected peptide sequences compared to those obtained by panning directly with Sv. The consensus XXYYLH was identified with the anti-biotin Ab probe, while GDWVFI and PWPWLG were the major motifs identified by Sv panning. Although some similarities were observed between sequences of the products from both pannings, only phage displaying the GDWVFI and PWPWLG peptides demonstrated biotin-sensitive Sv binding in ELISA and micropanning assays. Phage displaying GDWVFI could be eluted from Sv with either acid or biotin, but not phosphate-buffered saline (PBS), whereas phage displaying PWPWLG eluted with acid, biotin and PBS.