Selection of novel structural zinc sites from a random peptide library

Zinc ion (Zn2+) can be coordinated with four or three amino acid residues to stabilize a protein's structure or to form a catalytic active center. We used phage display selection of a dodecamer random peptide library with Zn2+ to identify structural zinc sites. The binding specificity for Zn2+ of selected sequences was confirmed using enzyme-linked immunosorbent and competitive inhibition assays. Circular dichroism spectra indicated that the interaction with Zn2+ induced a change in conformation, which means the peptide acts as a structural zinc site. Furthermore, a search of protein databases revealed that two selected sequences corresponded to parts of natural zinc sites of copper/zinc superoxide dismutase and zinc-containing ferredoxin. We demonstrated that Zn2+-binding sequences selected from the random combinatorial library would be candidates for artificial structural zinc sites. (C) 2003 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.