Peptide Arrays for Development of PDGFRβ Affine Molecules

Abstract

Peptide arrays represent an attractive method for identification of amino acid motifs that bind to target structures. Spotting derivatives of the linear peptide platelet-derived growth factor receptor (PDGFR)-P1, which has been identified to bind the extracellular domain of the platelet-derived growth factor receptor beta, allows the synchronous investigation of the target affinity of numerous ligands. A peptide array randomizing PDGFR-P1 was constructed by replacement of each amino acid by all 20 natural amino acids. Incubation of the array with PDGFRβ and fibroblast growth factor receptor as negative control target was performed. Selected derivatives and fragments of PDGFR-P1 were chemically synthesized, radiolabeled, and evaluated in cell-based assays, using human pancreatic carcinoma BxPC3 and human breast cancer MCF7 cells. Binding capacity was increased for the derivate yG2 by exchange of 7S to 7R. Competition experiments demonstrated a binding decrease with increasing competitor concentration. Serum stability of yG2 was improved compared to the native ligand. Peptide arrays were successfully applied for the improvement of the PDGFRβ binding peptide PDGFR-P1.