11/9-Mixed Helices in the α/β-Peptides Derived from Alternating α- and β-Amino Acids with Proteinogenic Side Chains.

α/β-Hybrid peptides are prepared from amino acids with proteinogenic side chains on the basis of the concept of “alternating chirality”, involving d-Phe and a β3-hVal. Through the extensive NMR, CD, and MD studies, robust left-handed 11/9-mixed helices were identified in these peptides in CDCl3 solutions, wherein the 11/9-mixed helix was observed even in a small peptide with three residues.