A target-unrelated peptide in an M13 phage display library traced to an advantageous mutation in the gene II ribosome-binding site.

Screening of the commercially available Ph.D.-7 phage-displayed heptapeptide library for peptides that bind immobilized Zn2+ resulted in the repeated selection of the peptide HAIYPRH, although binding assays indicated that HAIYPRH is not a zinc-binding peptide.