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In order to determine the ability of 1,2-dipalmitoyl phosphatidylcholine (DPPC) and 1,2-dioleoyl phosphatidylglycerol (DOPG) to host peptide sequences belonging to the E2 protein of GBV virus C/Hepatitis G virus, the behaviour of Langmuir monolayers formed by these phospholipids and E2 (12-26), E2 (354-363) and E2 (chimeric) peptide sequences was analysed from data of surface pressure (π) versus area per molecule (A) isotherms, compression modulus (C s -1 ), excess Gibbs energy of mixing (ΔG exc ) and total Gibbs energy of mixing (ΔG mix ). Three different behaviours were observed. Mixed films of E2 (12-26) with DPPC or DOPC showed negative values for the excess thermodynamic functions, and thus attractive interactions between mixed films components are greater than in ideal films. Mixtures of E2 (354-363) with DPPC or DOPG, exhibited positive values of excess functions, evidencing weaker interactions in the mixed films in relation to those of pure components. Finally, positive and negative excess functions were observed in E2 (chimeric)/DPPC or DOPG mixed films, depending on their composition. In short, the interaction between the phospholipids used in this work as models of cell membranes and E2 peptides varies with the type of phospholipid and the nature of the peptide (size, bulky, hydrophobicity and electric charge)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Lipidation of a short hydrophilic peptide has the aim to make the molecule amphiphilic, which improves its insertion into lipid monolayer and at the same time, the tendency to self-assembly. These both properties of two positively charged, hepatitis G (GBV-C/HGV) related lipidated peptides--palmitic acid derivatives of the fragments: 505-514 and the 513-522 of the NS3 protein (respectively Palmitoyl-SAELSMQRRG and Palmitoyl-RGRTGRGRSG) were studied. First, using transmission electron microscope (TEM) and atomic force microscope (AFM) the tendency to self-assembly in water solution was examined. Both techniques confirmed the formation of fibrous aggregates of Palmitoyl-SAELSMQRRG in water solution. At the same conditions, any fibrous aggregates of Palmitoyl-RGRTGRGRSG were detected neither by TEM nor by AFM. Insertion of the lipidated peptides into phospholipids monolayer formed by zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or negatively charged 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DPPG) was investigated. Monolayers prepared by Langmuir-Blodgett method were visualized by AFM. The presence of lipidated peptides in phospholipid monolayers produced changes in the monolayers and different morphologies of the monolayers were obtained for each of the lipidated peptides.