Mimicking hemoproteins: a new synthetic metalloenzyme based on a Fe(III)‐mesoporphyrin functionalized by two helical decapeptides

A new metalloenzyme formed by a Fe(III)‐mesoporphyrin IX functionalized by two helical decapeptides was synthesized to mimic function and structural features of a hemoprotein active site. Each decapeptide comprises six 2‐aminoisobutyric acid residues, which constrain the peptide to attain a helical conformation, and three glutamic residues for improving the solubility of the catalyst in aqueous solutions. The new compound shows a marked amphiphilic character, featuring a polar outer surface and a hydrophobic inner cavity that hosts the reactants in a restrained environment where catalysis may occur. The catalytic activity of this synthetic mini‐protein was tested with respect to the oxidation of l ‐ and d ‐Dopa by hydrogen peroxide, showing moderate stereoselectivity. Structural information on the new catalyst and its adduct with the l ‐ or d ‐Dopa substrate were obtained by the combined use of spectroscopic techniques and molecular mechanics calculations. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.