N- versus C-Terminal Control over the Screw-Sense Preference of the Configurationally Achiral, Conformationally Helical Peptide Motif Aib8GlyAib8

Conformational control over the screw sense of a helical 17-mer of achiral amino acids, Aib(8)GlyAib(8), from a single chiral residue located at the N-terminus is better than that from a single amino acid located at the C-terminus. X-ray crystallography indicates that Aib(8)GlyAib(8) forms the longest 3(10) helical structure observed crystallographically to date.