title: Interaction Study of Phospholipid Membranes with an N-Glucosylated β-Turn Peptide Structure Detecting Autoantibodies Biomarkers of Multiple Sclerosis.
abstract: The interaction of lipid environments with the type I' β-turn peptide structure called CSF114 and its N-glucosylated form CSF114(Glc), previously developed as a synthetic antigenic probe recognizing specific autoantibodies in a subpopulation of multiple sclerosis patients' serum, was investigated by fluorescence spectroscopy and electrochemical experiments using large unilamellar vesicles, mercury supported lipid self-assembled monolayers (SAMs) and tethered bilayer lipid membranes (tBLMs). The synthetic antigenic probe N-glucosylated peptide CSF114(Glc) and its unglucosylated form interact with the polar heads of lipid SAMs of dioleoylphosphatidylcholine at nonzero transmembrane potentials, probably establishing a dual electrostatic interaction of the trimethylammonium  and phosphate groups of the phosphatidylcholine polar head with the Glu⁵ and His⁸ residues on the opposite ends of the CSF114(Glc) β-turn encompassing residues 6-9. His⁸ protonation at pH 7 eliminates this dual interaction. CSF114(Glc) is adsorbed on top of SAMs of mixtures of dioleoylphosphatidylcholine with sphingomyelin, an important component of myelin, whose proteins are hypothesized to undergo an aberrant N-glucosylation triggering the autoimmune response. Incorporation of the type I' β-turn peptide structure CSF114 into lipid SAMs by potential scans of electrochemical impedance spectroscopy induces defects causing a slight permeabilization toward cadmium ions. The N-glucopeptide CSF114(Glc) does not affect  tBLMs to a detectable extent.
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy. luci_be@tiscali.it.|Department of Chemistry, University of Padova, Via Marzolo 1, 35131 Padova, Italy. luci_be@tiscali.it.
authors.forename: Lucia
authors.initials: L
authors.lastname: Becucci
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Benci
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Nuti
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.
authors.forename: Feliciana
authors.initials: F
authors.lastname: Real-Fernandez
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', Via Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Vaezi
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', Via Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Stella
authors.affiliation: Department of Chemical Sciences and Technologies, University of Rome 'Tor Vergata', Via Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Mariano
authors.initials: M
authors.lastname: Venanzi
authors.affiliation: Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|Department of Neurosciences, Psychology, Drug Research and Child Health-Section of Pharmaceutical Sciences and Nutraceutics, University of Florence, Via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Rovero
authors.affiliation: Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|Interdepartmental Laboratory of Peptide and Protein Chemistry and Biology, Via della Lastruccia 13, 50019 Sesto Fiorentino, Italy.|PeptLab@UCP Platform and Laboratory of Chemical Biology EA4505, University of Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise CEDEX, France.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Papini
keywords: autoantibodies; cyclic voltammetry; electrochemical impedance spectroscopy; fluorescence; large unilamellar vesicles; multiple sclerosis; self-assembled monolayers; tethered bilayer lipid membranes; β-turn peptide structures