Control of leakage activities of alamethicin analogs by metals: Side chain-dependent adverse gating response to Zn2+

Alamethicin (Alm), an antimicrobial peptide rich in α-aminoisobutyric acid (Aib), is known to self-assemble to form channels in the membranes. Previously, we reported that HG-Alm, an Alm analog with a single His residue at the N-terminus, forms channel assemblies with extremely long lifetimes in the presence of Zn²⁺. In this study, HG-Alm analogs, in the sequences of which all Aib residues were substituted by Leu, norvaline (Nva), or norleucine (Nle), were synthesized and their leakage activities were measured using fluorescent dye-loaded liposomes. We found that these peptides could be categorized into two classes with different gating responses to Zn²⁺.