Figure 7.

Schematic representation of the phage-display cyclic peptide probe synthesis and screening approach. Different peptides containing two cysteine residues on fixed positions are expressed on the PIII protein of phages. The phage peptide library is cyclized with a dichloroacetone-functionalized vinylsulfone (18) or fluorophosphonate (19) reactive group. The library is incubated with the immobilized target protein. After the labeling step, all the unbound phage is washed away. The bound phage is liberated by denaturing or by cleavage with a protease. The enriched phage is amplified in E. coli cells. After three cycles, the consensus sequence is determined by PCR.