Figure 1.

Schematic representation of the heptapeptides (P31–P37) designed from the all α amino acid containing template peptide P4. In peptides P31–P33, polar amino acid Lys of P4 was replaced by unnatural analogs such as Orn, Dab, and Dap; in P34, all of the nonpolar hydrophobic Leu residues in P4 were replaced by Nle; and in P35–37, both the Lys and Leu residues were simultaneously replaced by the unnatural analogs. The side chains of the unnatural amino acid residues are illustrated in the figure.