First-Principles Simulation of Dielectric Function in Biomolecules

Area of Science:

• Biophysics
• Computational Chemistry
• Protein Science

Background:

• Dielectric spectra of biomolecules reveal protein heterogeneity, crucial for understanding electrostatic and electrodynamic interactions.
• Protein dielectric response is influenced by size, structure, composition, and environment.

Purpose of the Study:

• To present a novel, robust simulation method for computing dielectric spectra of small proteins.
• To gain insights into protein dielectric properties under various conditions using rigorous ab initio calculations.

Main Methods:

• Developed a simulation method based on ab initio quantum mechanical calculations of explicit atomistic models.
• Applied the methodology to a polypeptide RGD-4C (1FUV) and the SD1 domain of SARS-CoV-2 spike protein.
• Investigated protein behavior in vacuum, solvated, and salted environments.

Main Results:

• Observed two distinct peaks in the dielectric absorption spectra for both 1FUV and SD1.
• These peaks consistently appeared at 5.2–5.7 eV and 14.4–15.2 eV across different environmental conditions.

Conclusions:

• The new simulation method provides reliable insights into protein dielectric spectra without indeterminate parameters.
• The observed spectral features are consistent across different protein models and environments, suggesting fundamental dielectric properties.