title: Using zeta-potential measurements to quantify peptide partition to lipid membranes.
abstract: Many cellular phenomena occur on the biomembranes. There are plenty of molecules (natural or xenobiotics) that interact directly or partially with the cell membrane. Biomolecules, such as several peptides (e.g., antimicrobial peptides) and proteins, exert their effects at the cell membrane level. This feature makes necessary investigating their interactions with lipids to clarify their mechanisms of action and side effects necessary. The determination of molecular lipid/water partition constants (K ( p )) is frequently used to quantify the extension of the interaction. The determination of this parameter has been achieved by using different methodologies, such as UV-Vis absorption spectrophotometry, fluorescence spectroscopy and ζ-potential measurements. In this work, we derived and tested a mathematical model to determine the K ( p ) from ζ-potential data. The values obtained with this method were compared with those obtained by fluorescence spectroscopy, which is a regular technique used to quantify the interaction of intrinsically fluorescent peptides with selected biomembrane model systems. Two antimicrobial peptides (BP100 and pepR) were evaluated by this new method. The results obtained by this new methodology show that ζ-potential is a powerful technique to quantify peptide/lipid interactions of a wide variety of charged molecules, overcoming some of the limitations inherent to other techniques, such as the need for fluorescent labeling.
authors.affiliation: Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal.
authors.forename: João M
authors.initials: JM
authors.lastname: Freire
authors.forename: Marco M
authors.initials: MM
authors.lastname: Domingues
authors.forename: Joana
authors.initials: J
authors.lastname: Matos
authors.forename: Manuel N
authors.initials: MN
authors.lastname: Melo
authors.forename: Ana Salomé
authors.initials: AS
authors.lastname: Veiga
authors.forename: Nuno C
authors.initials: NC
authors.lastname: Santos
authors.forename: Miguel A R B
authors.initials: MA
authors.lastname: Castanho
mesh_terms: D000890:Anti-Infective Agents / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D023181:Antimicrobial Cationic Peptides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry*; D008563:Membrane Lipids / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D008564:Membrane Potentials; D010713:Phosphatidylcholines / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D053835:Unilamellar Liposomes / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D005456:Fluorescent Dyes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D053835:Unilamellar Liposomes; D014867:Water