Cryo‐EM Structures Reveal Nonmirror‐Image Binding of L‐ and D‐Peptide Enantiomers at α7 Nicotinic Acetylcholine Receptor

Peptides targeting the α7 nicotinic acetylcholine receptor (α7‐nAChR) hold significant potential for biological research and therapeutic applications. Notably, linear D‐amino acid peptides exhibit higher inhibitory potency against α7‐nAChR and greater proteolytic stability compared to their L‐type counterparts, making them more attractive candidates for both laboratory research and clinical use. However, the molecular basis of D‐peptide binding to α7‐nAChR remains elusive. Herein, cryo‐EM structures of α7‐nAChR is presented in complex with the L‐peptide L KP1794 (2.68 Å) and its D‐peptide enantiomer D KP1794 (2.53 Å), providing the first molecular insights into D‐peptide recognition by α7‐nAChR. Structural analysis reveals that both peptides occupy the orthosteric site of α7‐nAChR. However, their binding poses are not merely mirror images; instead, they adopt a hybrid binding mode that combines mirror symmetry with a flipped peptide backbone orientation. Our structural data uncover a distinct D‐peptide binding mechanism that diverges from the hypothesized retro‐inversion model.