All-atom molecular dynamics simulations using orientational constraints from anisotropic NMR samples.

Area of Science:

• Biophysics
• Computational Chemistry
• Structural Biology

Background:

• Solid-state NMR experiments provide orientational constraints for molecules in anisotropic environments.
• Molecular dynamics (MD) simulations are crucial for understanding molecular structure and dynamics.
• Integrating experimental data into simulations enhances structural and dynamic predictions.

Purpose of the Study:

• To develop and validate a novel MD simulation technique using NMR orientational constraints.
• To determine the structure and dynamics of membrane-bound molecules with enhanced accuracy.
• To explore the distribution of segmental orientations and order parameter tensors.

Main Methods:

• Developed an MD technique incorporating orientation-dependent pseudo-forces into the COSMOS-NMR force field.
• Applied orientational constraints from deuterium quadrupolar couplings obtained via solid-state NMR.
• Simulated pyrene, cholesterol, and an antimicrobial peptide in oriented lipid bilayers.

Main Results:

• MD simulations successfully reproduced experimental NMR parameters within experimental error.
• Accurate determination of molecular alignment and conformation for membrane-bound systems.
• First-time reporting of segmental orientation distributions and order parameter tensors.

Conclusions:

• The novel MD approach accurately models membrane-bound molecule structure and dynamics.
• This method offers a powerful tool for integrating NMR data into computational studies.
• Provides new insights into the orientational behavior of molecules within lipid bilayers.