Selection of phage display combinatorial library peptides with affinity for a yohimbine imprinted methacrylate polymer

Abstract

α₂-Adrenoreceptor mimics, prepared by molecular imprinting of yohimbine, were used to select ligands from a phage display hexapeptide library. Phages with affinity for the yohimbine imprinted methacrylic acid–ethylene glycol dimethacrylate copolymer were selected. Phage affinities were estimated using an enzyme immunoassay. The selected library showed three-fold higher affinity for the imprinted polymer compared with the primary library. Eighty-two of ninety characterized phage clones from the selected library showed low affinity for the polymer. The hexapeptides on eight of these low binding phage clones consisted of mainly hydrophobic amino acid residues, and four clones were identical. The hexapeptides on five of the eight high affinity phage clones contained positively charged amino acids. Identical hexapeptides were expressed on four of these five clones. The results of this study suggest that the majority of the selected phages form hydrophobic and/or ionic interactions with the polymer framework rather than specific interactions only with the yohimbine imprinted sites. Furthermore, a direct correlation can be seen between hexapeptide sequence affinity and the number of positively charged amino acid residues they contain.