“…29 This secondary structure was expected to be of marginal stability when compared with the a-helix, under these experimental conditions, due to the unfavorable hydration of its carbonyl groups which are not oriented enough away from the helix axis. After several, only partially successful, attempts from our 30 and other [31][32][33][34][35][36] groups, we synthesized three terminally blocked heptapeptides, each containing (i) two residues of ATANP, 2-amino-3-[1-(1,4,7-triazacyclononane)]-L-propanoic acid (see Fig. 1), a chiral C a -trisubstituted a-amino acid with excellent water-solubilizing properties and (ii) five residues of C atetrasubstituted a-amino acids, either the achiral Aib or the chiral L-Iva (isovaline; Fig.…”