Structure Formation in Langmuir Peptide Films As Revealed from Coarse-Grained Molecular Dynamics Simulations

Area of Science:

• Biophysics
• Materials Science
• Computational Chemistry

Background:

• Poly(γ-benzyl-l-glutamate) (PBLG) peptides are helical structures.
• Understanding peptide behavior at interfaces is crucial for materials science.
• Previous studies assumed complete surface coverage by PBLG.

Purpose of the Study:

• Investigate the nonequilibrium behavior of PBLG peptides at the water/vapor interface.
• Characterize the structural changes and aggregation patterns of PBLG.
• Compare simulation results with experimental atomic force microscopy (AFM) data.

Main Methods:

• Utilized molecular dynamics simulations with the Martini coarse-grained model.
• Simulated 22-residue helical PBLG peptides at the water/vapor interface.
• Analyzed peptide aggregation, cluster formation, and fibril development.

Main Results:

• PBLG monolayers and bilayers laterally collapse, exposing water surfaces.
• Elongated clusters and fibrils form, with increasing heights over time.
• Simulated aggregate heights (3-4.5 nm) align with experimental AFM observations, corresponding to bi- or trilayer structures.

Conclusions:

• PBLG peptides do not maintain complete coverage at the water/vapor interface.
• Peptide aggregation leads to exposed water surfaces and the formation of distinct structures.
• Simulation results validate experimental findings and refine understanding of PBLG interfacial behavior.