[Ionic selectivity of melittin-modified flat lipid bilayers]

Area of Science:

• Biophysics
• Membrane Biophysics
• Protein-lipid interactions

Context:

• Bilayer lipid membranes (BLM) are crucial models for studying cellular membrane properties.
• Melittin, a peptide toxin, forms pores in lipid bilayers, influencing membrane permeability.
• Understanding ion transport through melittin pores is vital for cell membrane research.

Purpose:

• To investigate the pH-dependent ion selectivity of melittin pores in bilayer lipid membranes.
• To elucidate the role of the N-terminal glycine residue in melittin pore selectivity.
• To explore the influence of transmembrane potential on melittin pore characteristics.

Summary:

• Melittin pores exhibit cation selectivity at pH > 6.6 and anion selectivity at lower pH.
• The N-terminal glycine residue's amino group is identified as the key determinant of this pH-dependent selectivity.
• Transmembrane potential can alter the cross-section of water pores, thereby controlling membrane selectivity.

Impact:

• Provides insights into the mechanisms of ion transport across biological membranes.
• Highlights the potential for controlling membrane permeability through peptide modifications and electrical fields.
• Contributes to the understanding of melittin's biological activity and potential therapeutic applications.