Atomic Structure of a Short α-Helix Stabilized by a Main Chain Hydrogen-Bond Surrogate

Herein we report the 1.15 Å X-ray crystal structure of a short α-helix in which the N-terminal <i>i</i> and <i>i</i> + 4 main chain hydrogen bond is replaced with a carbon−carbon bond. The structure shows that the hydrogen-bond surrogate (HBS) derived α-helix truly resembles the structure of canonical α-helices and provides unequivocal support for our helix nucleation strategy.