Structural Characterization of Backbone‐Expanded Helices in Hybrid Peptides: (αγ)n and (αβ)n Sequences with Unconstrained β and γ Homologues of L‐Val

Learning your αβγ′s: The diversity of hydrogen-bonding patterns in backbone-expanded hybrid helices is shown by crystal-structure determination of several oligomeric peptides (see scheme; C=gray; H=white; O=red; N=blue). C12 helices were observed in the αγ peptide series for n=2–8. In comparison, the αα peptide and αβ peptide sequences show C10 and mixed C14/C15 helices, respectively.