title: Defect formation of lytic peptides in lipid membranes and their influence on the thermodynamic properties of the pore environment.
abstract: We present an experimental study of the pore formation processes of small amphipathic peptides in model phosphocholine lipid membranes. We used atomic force microscopy to characterize the spatial organization and structure of alamethicin- and melittin-induced defects in lipid bilayer membranes and the influence of the peptide on local membrane properties. Alamethicin induced holes in gel DPPC membranes were directly visualized at different peptide concentrations. We found that the thermodynamic state of lipids in gel membranes can be influenced by the presence of alamethicin such that nanoscopic domains of fluid lipids form close to the peptide pores, and that the elastic constants of the membrane are altered in their vicinity. Melittin-induced holes were visualized in DPPC and DLPC membranes at room temperature in order to study the influence of the membrane state on the peptide induced hole formation. Also differential scanning calorimetry was used to investigate the effect of alamethicin on the lipid membrane phase behaviour.
authors.affiliation: Complex Fluids Group, Drittes Physikalisches Institut, Georg-August Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Oliynyk
authors.forename: Udo
authors.initials: U
authors.lastname: Kaatze
authors.forename: Thomas
authors.initials: T
authors.lastname: Heimburg
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D000408:Alamethicin / Q000494:pharmacology; D002152:Calorimetry, Differential Scanning; D002462:Cell Membrane; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D007202:Indicators and Reagents / Q000737:chemistry; D007476:Ionophores / Q000494:pharmacology; D008051:Lipid Bilayers / Q000737:chemistry*; D008555:Melitten / Q000494:pharmacology; D008560:Membrane Fluidity; D021962:Membrane Microdomains; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force; D013816:Thermodynamics
chemical_list: D007202:Indicators and Reagents; D007476:Ionophores; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D008555:Melitten; D015060:1,2-Dipalmitoylphosphatidylcholine; D000408:Alamethicin; D004134:Dimyristoylphosphatidylcholine