Samples were dialyzed into 20 mM sodium phosphate pH 7.5, 150 mM NaCl, and 5% glycerol and concentrated or diluted to a peptide concentration of about 0.13 mg/mL for Mono-M2e and about 0.05 mg/mL for Tetra-M2e. Circular dichroism measurements were performed at room temperature using an Applied Photophysics (Surrey, UK) Pi Star 180 spectropolarimeter, taking measurements from 200 to 250 nm.