title: riDOM, a cell penetrating peptide. Interaction with phospholipid bilayers.
abstract: Melittin is an amphipathic peptide which has received much attention as a model peptide for peptide-membrane interactions. It is however not suited as a transfection agent due to its cytolytic and toxicological effects. Retro-inverso-melittin, when covalently linked to the lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (riDOM), eliminates these shortcomings. The interaction of riDOM with phospholipid membranes was investigated with circular dichroism (CD) spectroscopy, dynamic light scattering, ζ-potential measurements, and high-sensitivity isothermal titration calorimetry. riDOM forms cationic nanoparticles with a diameter of ~13nm which are well soluble in water and bind with high affinity to DNA and lipid membranes. When dissolved in bilayer membranes, riDOM nanoparticles dissociate and form transient pores. riDOM-induced membrane leakiness is however much reduced compared to that of authentic melittin. The secondary structure of the ri-melittin is not changed when riDOM is transferred from water to the membrane and displays a large fraction of β-structure. The (31)P NMR spectrum of the nanoparticle is however transformed into a typical bilayer spectrum. The Gibbs free energy of riDOM binding to bilayer membranes is -8.0 to -10.0kcal/mol which corresponds to the partition energy of just one fatty acyl chain. Half of the hydrophobic surface of the riDOM lipid extension with its 2 oleic acyl chains is therefore involved in a lipid-peptide interaction. This packing arrangement guarantees a good solubility of riDOM both in the aqueous and in the membrane phase. The membrane binding enthalpy is small and riDOM binding is thus entropy-driven.
authors.affiliation: Biozentrum, University of Basel, Div. of Biophysical Chemistry, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland. Electronic address: gabriela.quebatte@unibas.ch.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Québatte
authors.affiliation: F. Hoffmann-La Roche Ltd., Pharma Research and Early Development Discovery Chemistry, Grenzacherstrasse 124, CH-4070 Basel, Switzerland. Electronic address: eric_a.kitas@roche.com.
authors.forename: Eric
authors.initials: E
authors.lastname: Kitas
authors.affiliation: Biozentrum, University of Basel, Div. of Biophysical Chemistry, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland. Electronic address: joachim.seelig@unibas.ch.
authors.forename: Joachim
authors.initials: J
authors.lastname: Seelig
mesh_terms: D002151:Calorimetry; D002463:Cell Membrane Permeability; D002942:Circular Dichroism; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D008555:Melitten / Q000737:chemistry / Q000378:metabolism*; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D008051:Lipid Bilayers; D008563:Membrane Lipids; D010714:Phosphatidylethanolamines; D008555:Melitten; C020888:1,2-dielaidoylphosphatidylethanolamine
keywords: Cell penetrating peptide; Melittin; Peptide–membrane interaction; Pore formation; Thermodynamic; Transfection