Study of the interaction of GB virus C/Hepatitis G virus fusion peptides belonging to the E2 protein with phospholipid Langmuir monolayers

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).