Isolation of fibroblast growth factor receptor binding sequences using evolved phage display libraries

A fusion protein construct consisting of the short form of human fibroblast growth factor (FGFR) fused to the heavy chain of mouse IgG1 was used to sc reen four phage display libraries displaying 8, 13, 38 and 43 amino acids a t the amino terminus of the bacteriophage M13 gene III minor coat protein. Phage with specific FGFR binding activity were isolated from the 13, 38 and 43mer libraries. One of the highest affinity phage clones from the 13mer l ibrary was chosen to be further evolved by oligonucleotide saturation mutag enesis. We have isolated evolved sequences that have approximately 8 times the:relative binding affinity of the parent sequence. The phage clones have a minimum consensus sequence of CR/SXLLXGAPFXXXXC, where X represents posi tions: tolerant of several amino acids. A synthetic peptide based on this s equence specifically inhibits FGF from binding to its receptor in an in vit ro ELISA.