Structural properties of CHAPS micelles, studied by molecular dynamics simulations

Area of Science:

• Biochemistry
• Computational Chemistry
• Molecular Biophysics

Background:

• Detergents like CHAPS are crucial for solubilizing lipids and proteins in biological membrane studies.
• CHAPS, a non-denaturing zwitterionic detergent, combines features of sulfobetaines and bile salts.
• The precise molecular structure of CHAPS micelles remains incompletely understood despite its utility.

Purpose of the Study:

• To investigate the aggregation and micelle formation of CHAPS using molecular dynamics simulations.
• To develop and validate accurate force field parameters for CHAPS molecules.
• To characterize the molecular shape and structure of CHAPS micelles.

Main Methods:

• Molecular dynamics simulations of CHAPS aggregation in aqueous solutions.
• Development and validation of novel force field parameters for CHAPS.
• Analysis of micelle properties including gyration radii, volume, surface area, RDF, salt bridges, H-bonds, and SAS.

Main Results:

• Stable CHAPS micelles formed after 50 ns simulations for systems with up to 18 CHAPS molecules.
• Electrostatic interactions between polar groups and hydroxyls on the ring moiety are critical for micelle stability.
• CHAPS micelles exhibit grain-like heterogeneity with distinct hydrophobic micropockets, unlike other detergent micelles.

Conclusions:

• The study successfully modeled the molecular structure of CHAPS micelles, consistent with experimental data (NMR, TEM, SAXS).
• Developed force field parameters provide a valuable tool for future simulations involving CHAPS.
• This work significantly contributes to understanding the behavior and structure of CHAPS in membrane studies.