title: Simultaneous Analysis of Secondary Structure and Light Scattering from Circular Dichroism Titrations: Application to Vectofusin-1.
abstract: Circular Dichroism data are often decomposed into their constituent spectra to quantify the secondary structure of peptides or proteins but the estimation of the secondary structure content fails when light scattering leads to spectral distortion. If peptide-induced liposome self-association occurs, subtracting control curves cannot correct for this. We show that if the cause of the light scattering is independent from the peptide structural changes, the CD spectra can be corrected using principal component analysis (PCA). The light scattering itself is analysed and found to be in good agreement with backscattering experiments. This method therefore allows to simultaneously follow structural changes related to peptide-liposome binding as well as peptide induced liposome self-association. We apply this method to study the structural changes and liposome binding of vectofusin-1, a transduction enhancing peptide used in lentivirus based gene therapy. Vectofusin-1 binds to POPC/POPS liposomes, causing a reversal of the negative liposome charge at high peptide concentrations. When the peptide charges exactly neutralise the lipid charges on both leaflets reversible liposome self-association occurs. These results are in good agreement with biological observations and provide further insight into the conditions required for efficent transduction enhancement.
authors.affiliation: University of Strasbourg, Institute of Chemistry, CNRS, UMR 7177, Membrane Biophysics and NMR group, 1 rue Blaise Pascal, 67000 Strasbourg, France.
authors.forename: Louic S
authors.initials: LS
authors.lastname: Vermeer
authors.affiliation: University of Strasbourg, Institute of Chemistry, CNRS, UMR 7177, Membrane Biophysics and NMR group, 1 rue Blaise Pascal, 67000 Strasbourg, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marquette
authors.affiliation: University of Strasbourg, Institute of Chemistry, CNRS, UMR 7177, Membrane Biophysics and NMR group, 1 rue Blaise Pascal, 67000 Strasbourg, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Schoup
authors.affiliation: Généthon, INSERM UMR S951, 1 rue de l'Internationale, F-91002 Evry, France.
authors.forename: David
authors.initials: D
authors.lastname: Fenard
authors.affiliation: Généthon, INSERM UMR S951, 1 rue de l'Internationale, F-91002 Evry, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Galy
authors.affiliation: University of Strasbourg, Institute of Chemistry, CNRS, UMR 7177, Membrane Biophysics and NMR group, 1 rue Blaise Pascal, 67000 Strasbourg, France.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Bechinger