Selection of peptides with affinity for single stranded DNA using a phage display library.

A hexapeptide phage library was used to affinity select peptides which interact with single stranded heptaoligonucleotides consisting of cytosine (oligo-C). Selections were performed in two different buffer systems, 50 mM 2[N-Morpholino]ethanesulphonic acid(MES)-buffer, pH 5.5, and 50 mM Tris(hydroxymethyl)-aminomethane, 150 mM NaCl, pH 7.5, respectively. Selection was more successful in 50 mM MES-buffer and three clones with affinity for oligo-C were further investigated. The peptides, Pro-Pro-Pro-Leu-Tyr-Phe, Arg-Phe-Cys-Asp-Thr-Ser and Arg-Ser-Arg-Leu-Ile-Trp, all interacted more strongly with oligo-C compared to the original peptide phage library and wildtype phage. The selected clones also showed different specificity in the interaction with oligo-C, -G, -A and -T.