Study of Adsorption and Penetration of E2(279−298) Peptide into Langmuir Phospholipid Monolayers

Abstract

The peptide corresponding to the sequence (279-298) of the Hepatitis G virus (HGV/GBV-C) E2 protein was synthesized, and surface activity measurements, pi-A compression isotherms, and penetration of E2(279-298) into phospholipid monolayers spread at the air-water interface were carried out on water and phosphate buffer subphases. The results obtained indicated that the pure E2(279-298) Langmuir monolayer exhibited a looser packing on saline-buffered than on pure water subphase and suggest that the increase in subphase ionic strength stabilizes the peptide monolayer. To better understand the topography of the monolayer, Brewster angle microscopy (BAM) images of pure peptide monolayers were obtained. Penetration of the peptide into the pure lipid monolayers of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine (DMPC) and into mixtures of dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) at various initial surface pressures was investigated to determine the ability of these lipid monolayers to host the peptide. The higher penetration of peptide into phospholipids is attained when the monolayers are in the liquid expanded state, and the greater interaction is observed with DMPC. Furthermore, the penetration of the peptide dissolved in the subphase into these various lipid monolayers was investigated to understand the interactions between the peptide and the lipid at the air-water interface. The results obtained showed that the lipid acyl chain length is an important parameter to be taken into consideration in the study of peptide-lipid interactions.

Interaction of the cationic peptide bactenecin with mixed phospholipid monolayers at the air–water interface

“…34 mN/m similar, for example, to that obtained by Miñones et al [31] (33 mN/m) for another phospholipid mixture (DMPC:DMPG). Thus, we conclude that the peptide adsorption is mostly caused by the negative charge of DMPG molecules when compared with the behavior displayed by pure DPPC monolayer, for which no peptide adsorption was observed [39].…”

“…They have been extensively studied by a broad range of techniques, leading to detailed information on both structure and molecular orientation of their constituents [28][29][30]. Studies on mixed monolayers by air-water interface isotherms provide information about the interactions, miscibility, and stability of the monolayer [10,31]. Complementary information is obtained from images of Langmuir-Blodgett films, by atomic force microscopy (AFM) measurements.…”

GB virus type C interactions with HIV: the role of envelope glycoproteins

“…Lipid mixing and red blood cell haemolysis studies identified the 279–298 peptide as more able to disrupt lipid bilayers, suggesting that it is more likely to be an internal fusion peptide than the 267–284 peptide [58,60]. Additional physiochemical analyses with Langmuir phospholipid monolayers demonstrate that the 279–298 peptide modifies the surface behaviour of phospholipid monolayers, further suggesting that this peptide may be involved in membrane fusion [61]. Of note, the 279–298 peptide is unstructured in aqueous solution, but forms an amphipathic helical structure in the presence of lipids and model membranes, further supporting a role in virus-cell fusion [62].…”

Spectrin-like Repeats 11–15 of Human Dystrophin Show Adaptations to a Lipidic Environment

“…Air/Liquid Interface Measurements-The experiments in the absence of lipid at the air/liquid interface, prior to lipid/liquid interface, allow determination of the following: (i) the amphiphilic properties of the protein; (ii) the concentration at which the protein saturates the lipid-free interface (16) in a way to minimize the protein aggregation that could result from a high protein concentration; and (iii) the concentration of the protein (13). Underlined residues indicate the start (N terminus column) or end (C terminus column) residue of the repeat from the alignment of Koenig and Kunkel (57).…”