Applications of Designed Alpha‐Helical Metallopeptides

Abstract

A variety of strategies have been employed to generate alpha‐helical peptides to mimic native protein‐protein interactions. Here, we present applications of a method that induces secondary structure in short peptides using engineered metal‐binding sites. We propose that the incorporation of metal ions to create helical peptides provides additional benefits that the more widely utilized covalent crosslinking methods lack. We have created a peptide system designed to bind ribose 5‐phosphate isomerase B (RpiB), a protein target in developing treatments for Chagas disease caused by Trypanosoma cruzi. In this system, we have compared peptide structure and stability when using our metal‐crosslinking system to hydrocarbon, lactam, and thioether staples across 1‐ or 2‐turns of an alpha‐helix. We have also measured the ability of each of these peptide constructs to bind RpiB and prevent homodimerization, which is required for parasitic activity. Further, we have studied whether metal‐bound peptides are better able to cross cellular membranes and enter the cytoplasm of mammalian cells compared to metal‐free peptides, as has been previously suggested in the literature, and deduced the impact of metal ion charge, identity, and secondary structure in enhanced permeability.