3D-Structure of the interior fusion peptide of HGV/GBV-C by 1H NMR, CD and molecular dynamics studies

In this work, we present a structural characterization of the putative fusion peptide E2(279-298) corresponding to the E2 envelope protein of the HGV/GBV-C virus by 1H NMR, CD and MD studies performed in H2O/TFE and in lipid model membranes. The peptide is largely unstructured in water, whereas in H2O/TFE and in model membranes it adopts an helical structure (approximately 65-70%). The partitioning free energy ΔG ranges from −6 to −7.5 kcal mol−1. OCD measurements on peptide-containing hydrated and oriented lipid multilayers showed that the peptide adopts a predominantly surface orientation. The 1H NMR data (observed NOEs, deuterium exchange rates, Hα chemical shift index and vicinal coupling constants) and the molecular dynamics calculations support the conclusions that the peptide adopts a stable helix in the C-terminal 9-18 residues slightly inserted into the lipid bilayer and a major mobility in the amino terminus of the sequence (1-8 residues).