Conformational sampling of peptides in cellular environments.

Area of Science:

• Biophysics
• Computational Biology
• Molecular Dynamics

Background:

• Biological systems are complex environments influenced by dielectric properties.
• High concentrations of macromolecules and cosolvents reduce cellular dielectric constants, impacting biomolecule conformational sampling.

Purpose of the Study:

• To investigate the effect of varying dielectric environments on the conformational preferences of peptides.
• To understand how reduced dielectric constants influence peptide structure and sampling.

Main Methods:

• Utilized computer simulations based on the generalized Born methodology.
• Studied alanine dipeptide, poly-alanine, and melittin in diverse dielectric environments.

Main Results:

• Extended conformations are favored over alpha-helical conformations for alanine dipeptide at dielectric constants ≤ 10.
• Lower dielectric environments (ε = 20) stabilize helical structures in poly-alanine.
• Melittin exhibits shifts in conformational equilibrium, favoring extended helices in low dielectrics and compact, V-shaped structures in higher dielectrics.

Conclusions:

• Reduced dielectric environments, rather than specific molecular details, are key drivers of helix stabilization and conformational shifts in peptides.
• Findings predict altered peptide sampling in dense cellular environments with reduced dielectric response.