title: Dicynthaurin (ala) monomer interaction with phospholipid bilayers studied by fluorescence leakage and isothermal titration calorimetry.
abstract: The interaction of the antimicrobial peptide dicynthaurin (ala) monomer with model membranes of zwitterionic and negatively charged lipids and mixtures thereof was studied by means of isothermal titration calorimetry (ITC), fluorescent leakage, and dynamic light scattering (DLS) measurements. For the ITC analysis, we have applied the surface partitioning equilibrium model which shows that the interaction is predominately driven by hydrophobic effects (Kb between 2 x 10(4) and 1 x 10(5) M(-1)). Under low salt conditions, the enhanced electrostatic interaction leads to larger peptide concentrations immediately above the vesicle surface, which initiates the insertion of the peptide into the bilayer more effectively. Fluorescent leakage measurements have shown a fast leakage of the fluorescent dye within seconds after peptide addition. The analysis of the leakage kinetics was performed in terms of an initial pore formation model (up to t = 1000 s) that takes the reversible surface aggregation of bound peptide monomers into account. From this analysis, a minimum aggregation number of n = 7 +/- 2 per pore is obtained.
authors.affiliation: Institute of Medical Physics & Biophysics, University of Leipzig, 04107 Leipzig, Germany.
authors.forename: Shaoying
authors.initials: S
authors.lastname: Wen
authors.forename: Monika
authors.initials: M
authors.lastname: Majerowicz
authors.forename: Alan
authors.initials: A
authors.lastname: Waring
authors.forename: Frank
authors.initials: F
authors.lastname: Bringezu
mesh_terms: D002151:Calorimetry; D005453:Fluorescence; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000493:pharmacokinetics*; D016062:Porosity; D012542:Scattering, Radiation; D055672:Static Electricity; D017186:Titrimetry
chemical_list: D008051:Lipid Bilayers; D010455:Peptides; C437228:dicynthaurin