Screening of ICAM-1-binding Peptide and Their Biological Functions

Two methods were used to screen intercellular adhesion molecule-1 (ICAM-1) binding peptides from phage-displayed random 15-peptide library. After 4-5 rounds affinity panning and ELISA analysis, six positive recombinant phage clones that could bind to ICAM-1 specifically were chosen. The DNA sequences of these positive clones were determined and amino acid sequences of 15-peptide were deduced. The affinity of the six positive recombinant phage clones was determined by ELISA. The space conformations of the peptides that had the consensus sequence were analyzed by computer-guided homologous modeling technique. The results showed that the No.4 peptide had the best affinity to ICAM-1. The amino acid sequence of the target peptide was GRGEFRGRDNSVSVV. The K a of No.4 displayed phage clone was 7.87×107 L/mol. The target peptide was synthesized and purified in vitro. It was also labeled with fluorescence for future study. The combination of target peptide with ICAM-1 depended upon concentration. The synthetic peptide could combine with ICAM-1 on inflammatory tissues by immunohistochemical staining. It also could accumulate toward ICAM-1 in vivo. It suggested that the target peptide might be used as the guiding peptide in “peptide guided drug to inflammatory site with ICAM-1 expression in the future.