Behavior of a Peptide during a Langmuir-Blodgett Compression Isotherm: A Molecular Dynamics Simulation Study

A detailed characterization of the behavior of the amphiphilic antimicrobial peptide Trichogin GA IV (TRIC) at the air/water interface during a Langmuir−Blodgett (LB) isotherm is reported. By means of molecular dynamics simulations, experimental data are explained in terms of the conformational changes and aggregate features adopted by TRIC. We show that, due to compression, different structural changes occur: initially formed drop-like aggregates coalesce, forming nanofibers; on increasing the surface tension further, these nanofibers constitute a web-like structure in which meshes are filled by water pools. During these transitions, the peptide chains lie almost parallel to the surface mostly adopting a helical conformation. At high peptide concentration, reaching the maximum of the allowed surface pressure, a monolayer of TRICs in nonhelical conformation and vertically aligned with respect to the air/water interface is formed.