A method of preserving the α-helix secondary structure of N-Acetyl-D-Asp-D-Trp-D-Phe-D-Lys-D-Ala-D-Phe-D-Tyr-D-Asp-D-Lys-D-Val-D-Ala-D-Glu-D-Lys-D-Phe-D-Lys-D-Glu-D-Ala-D-Phe-Amide or N-Acetyl-L-Asp-L-Trp-L-Phe-L-Lys-L-Ala-L-Phe-L-Tyr-L-Asp-L-Lys-L-Val-L-Ala-L-Glu-L-Lys-L-Phe-L-Lys-L-Glu-L-Ala-L-Phe-Amide and compositions comprising such peptides are disclosed.