Molecular organization of dengue fusion peptide in phospholipid monolayers revealed by tensiometry and vibrational spectroscopy.

The interaction of Dengue fusion peptide (FLAg) in selected lipid Langmuir monolayers was characterized with surface pressure-area isotherms and infrared spectroscopy to investigate the role of the membrane charge and molecular organization in the peptide-lipid binding. Surface pressure-area isotherms were employed to analyze the thermodynamic and mechanical properties of the FLAg-lipid monolayer, showing that charged lipid monolayers showed different peptide adsorption patterns for an optimized peptide concentration (maximum membrane adsorption). Polarization modulation infrared reflection-absorption spectroscopy pointed out that incorporating FLAg changed the dipole orientations for the lipid polar head groups, as confirmed in PG-containing monolayers. Also, FLAg reorients the lipid film when it interacts with the phosphate and choline groups. Finally, analysis of the 310-helix bands suggests that FLAg assumes a configuration as a hairpin, an essential premise for the beginning of the membrane fusion process.