Analysis of the effect of a peptide sequence of the E2 protein (HGV/GBV-C) on the physicochemical properties of zwitterionic and negatively charged bilayers. |
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Authors: | Maite Alay M Asunción Alsina Isabel Haro Josefina Prat M Antònia Busquets |
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Institution: | Associated Unity to the CSIC, Peptides and Proteins: Physical Chemistry Studies, Physical Chemistry Department, Faculty of Pharmacy, University of Barcelona, Av. Joan XXIII, s/n 08028 Barcelona, Spain. |
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Abstract: | The membrane-interacting properties of a potential epitope of GB virus C/hepatitis G virus located at the region (99-118) of the E2 structural protein were investigated using several fluorescence techniques. SUV of DMPC:DPPC (1:1) or DMPG:DPPC (1:1) zwitterionic and anionic mixtures, respectively, were used as model membranes. FRET with NBD-PE as energy donor and Rho-PE as energy acceptor-labelled SUV indicated that the peptide was able to fuse both zwitterionic and anionic SUVs, the latter requiring lower peptide concentrations. However, the peptide increased the steady-state anisotropy of DPH embedded in the hydrophobic centre of the membrane with zwitterionic headgroups and to a lesser extent in anionic bilayers, suggesting that charge-charge interactions are not required for membrane interactions and also confirming the FRET results. No changes in anisotropy were observed with the probe TMA-DPH located at the surface of the bilayer. Finally, analysis of the intrinsic emission fluorescence of the tryptophan residue, upon incubation with SUV, showed a blue shift in the presence of anionic bilayers, both below and above the main transition temperature (T(m)) (gel to liquid-crystalline state) and, to a lesser extent, with the zwitterionic model membrane. |
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Keywords: | HGV/GBV‐C synthetic peptide liposomes anisotropy Trp fluorescence FRET |
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