Abstract: A new method for the rapid and efficient screening of affinity ligands to biological targets is reported. The fusion peptide of influenza virus A was used as the model target and immobilized on the PGMA beads. Antisense peptide YRSKQA of fusion peptide was chosen as the lead compound. The special positional scanning peptide libraries were designed based on YRSKQA and synthesized by utilizing solid phase peptide synthesis manually. The libraries were YRSKQX, YRSKXA, YRSXQA, YRXKQA, YXSKQA and XRSKQA, where X represented 18 L-amino acids(except for Cys and Trp). Each library was screened by affinity chromatography. The eluates from the fusion peptide affinity column were collected and analyzed by RP-HPLC and MS, respectively, in order to determine the kind of X at each position. After the preferred residues of six positions were decided, the two preferred peptide sequences, GRGKHK and TRGKHK, were obtained. The dissociation constants of GRGKHK, TRGKHK and YRSKQA, were 3.35×10^-6, 5.24×10^-6and 1.15×10^-5 mol·L^-1, respectively. The preferred peptides showed the higher affinity binding to immobilized fusion peptide than the lead peptide.

Key words: Combinatorial peptide libraries, Affinity ligands, Dissociation constant, Solid phase peptide synthesis