Structure-function relationship of model Aib-containing peptides as ion transfer intermembrane templates.

Area of Science:

• Biochemistry
• Biophysics
• Molecular Biology

Background:

• Peptaibols are peptide antibiotics characterized by 2-aminoisobutyric acid (Aib) residues and C-terminal amino alcohols.
• These peptides adopt alpha-helical structures, enabling the formation of voltage-gated ion channels in lipid membranes.

Purpose of the Study:

• To investigate the aggregation and transmembrane orientation mechanisms of amphiphilic helical Aib-containing peptides.
• To design and synthesize peptides of varying chain lengths (n=1-5) with the sequence Ac-(Aib-Lys-Aib-Ala)n-NH2.
• To evaluate the antimicrobial activity and ion channel formation capabilities of these synthetic peptides.

Main Methods:

• Peptide synthesis utilizing the conventional stepwise Fmoc solid-phase method.
• Circular Dichroism (CD) spectroscopy for conformational analysis and helicity assessment.
• Liposome incorporation and patch-clamp electrophysiology for ion channel characterization.

Main Results:

• Peptides were synthesized with high yields (66-85%) and purities (69-95%).
• Helicity increased with peptide chain length, with the longest peptide (n=5) adopting a barrel-stave conformation in liposomes.
• The Ac-(Aib-Lys-Aib-Ala)5-NH2 peptide showed potent activity against Gram-positive bacteria and formed stable ion channels (227 pS conductance) at low potentials.

Conclusions:

• Amphiphilic Aib-containing peptides can self-aggregate and form transmembrane ion channels.
• Peptide chain length significantly influences helicity, aggregation, and ion channel formation.
• The longest peptide exhibits promising potential as an antimicrobial agent and ion channel-forming molecule.