Synthesis and ion channel formation of novel cyclic peptides containing a non-natural amino acid

A series of novel cyclic peptides possessing an alternate natural/non-natural amino acid sequence were prepared from L-alanine and 5-(N-acylamino)-3-aminobenzoic acid with a long acyl chain. Upon examination by the voltage clamp method, membranes composed of the synthetic cyclic peptides with varying ring sizes and side-chain lengths were found to form cation selective channels with a conductance of ca. 9 pS in aqueous KCl (500 mM).