Development and Validation of a DFT-Based Force Field for a Hydrated Homoalanine Polypeptide

Area of Science:

• Computational Chemistry
• Molecular Dynamics
• Biophysics

Background:

• Accurate simulation of hydrated polypeptides is crucial for understanding protein structure and function.
• Existing force fields often struggle to precisely capture the conformational dynamics of alanine-based peptides in aqueous environments.

Purpose of the Study:

• To develop and validate a novel force field for simulating hydrated alanine polypeptides.
• To improve the accuracy of predicting conformational ensembles and NMR scalar coupling constants.

Main Methods:

• Utilized the adaptive force matching (AFM) method for force field parameterization.
• Employed density functional theory (DFT) calculations with the Perdew-Burke-Ernzerhof functional and D3 dispersion correction.
• Validated the new force field (AFM2020) against experimental NMR data and compared it with other models.

Main Results:

• The AFM2020 force field demonstrates superior agreement with experimental NMR scalar coupling constants for hydrated homopolymeric alanine.
• Simulations of Ala7 reveal a conformational distribution of approximately 15% helical, 20% β-sheet, and 65% polyproline II.
• Predicted helical populations for short hydrated alanine are higher than previous estimates.

Conclusions:

• The AFM2020 force field offers enhanced accuracy for simulating hydrated alanine polypeptides.
• The developed force field shows promise for predicting peptide conformations in both solution and vacuum (e.g., protein interiors).
• This advancement aids in more reliable molecular dynamics simulations of biological systems.