A bimetallic helical heptapeptide as a transphosphorylation catalyst in water

A terminally protected heptapeptide based on alpha-aminoisobutyric acide residues, and carrying two triazacyclononane-functionalized residues at sequence positions 2 and 6 provides the first example of a very short peptide highly organized in a 3(10)-helical conformation in neutral aqueous solution. Its dinuclear complex with Zn(II) is a catalyst of the intramolecular transesterification of HPNP, a RNA model substrate, with a clear indication of cooperativity between the two Zn(II) ions in the catalytic process. Hence, we succeeded in demonstrating that very short, easily accessible, economically synthesized, and rationally designed peptide sequences may provide the appropriate scaffold for the realization of effective catalysts by controlling their secondary structure.