De Novo Screening and Mirror Image Isomerization of Linear Peptides Targeting α7 Nicotinic Acetylcholine Receptor

As ligand-gated ion channels, nicotinic acetylcholine receptors (nAChRs) are widely distributed in the central and peripheral nervous systems and are associated with the pathogenesis of various degenerative neurological diseases. Here, we report the results of phage display-based de novo screening of an 11-residue linear peptide (named ^LKP1794) that targets the α7 nAChR, which is among the most abundant nAChR subtypes in the brain. Moreover, two d-peptides were generated through mirror image and/or primary sequence inverso isomerization (termed ^DRKP1794 and ^DKP1794) and displayed improved inhibitory effects (IC₅₀ = 0.86 and 0.35 μM, respectively) on α7 nAChR compared with the parent l-peptide ^LKP1794 (IC₅₀ = 2.48 μM), which markedly enhanced serum stability. A peptide-based fluorescence probe was developed using proteolytically resistant ^DKP1794 to specifically image the α7 nAChR in living cells. This work provides a new peptide tool to achieve inhibitory modulation and specifically image the α7 nAChR.