title: The interaction of the cell-penetrating peptide penetratin with heparin, heparansulfates and phospholipid vesicles investigated by ESR spectroscopy.
abstract: An ESR investigation of the interaction of spin-labelled penetratin with heparin, heparansulfates and several phospholipid vesicle formulations is reported. Penetratin is a 16-aa peptide corresponding to the third helix of the Antennapedia homeodomain and belonging to the cell-penetrating peptide family. The present study shows that ESR spectroscopy can provide specific and reliable information about the mechanism of interaction of penetratin with polysaccharides and lipids, at a molecular level. The study showed that: (i) heparin and heparansulfates specifically interact with spin-labelled penetratin and promote peptide aggregation and concentration on their molecular surface; (ii) penetratin does not interact with neutral lipids, whereas it enters negatively charged lipid bilayers; (iii) cholesterol plays a negative effect on the insertion of penetratin into the lipid membrane; (iv) the interaction of penetratin with lipid vesicles is strongly dependent on lipid concentration. In a low lipid regime, penetratin associates with the polar heads of phospholipids and aggregates on the membrane surface; once the lipid concentration attains a threshold, the peptide enters the lipid bilayer. This step is characterized by reduced peptide mobility and partial disaggregation.It has been shown that ESR spectroscopy is a valuable investigation tool in studies related to the still unclear mechanism of the internalization process.
authors.affiliation: Dipartimento Chimica I.F.M., Università di Torino, Via Giuria 7, 10125 Torino, Italia. elena.ghibaudi@unito.it
authors.forename: E
authors.initials: E
authors.lastname: Ghibaudi
authors.forename: B
authors.initials: B
authors.lastname: Boscolo
authors.forename: G
authors.initials: G
authors.lastname: Inserra
authors.forename: E
authors.initials: E
authors.lastname: Laurenti
authors.forename: S
authors.initials: S
authors.lastname: Traversa
authors.forename: L
authors.initials: L
authors.lastname: Barbero
authors.forename: R P
authors.initials: RP
authors.lastname: Ferrari
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D002784:Cholesterol / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006493:Heparin / Q000737:chemistry / Q000378:metabolism*; D006497:Heparan Sulfate / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008081:Liposomes; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding
chemical_list: D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D002784:Cholesterol; D006493:Heparin; D006497:Heparan Sulfate; D008024:Ligands; D008081:Liposomes; D010743:Phospholipids; C414409:penetratin