TDDFT-Based Study on the Proton-DNA Collision.

Area of Science:

• Biophysics
• Computational Chemistry
• Radiation Biology

Background:

• Understanding DNA damage from heavy charged particles is crucial for hadron therapy and aerospace applications.
• Proton interactions with biological molecules like DNA are key to radiation effects.

Purpose of the Study:

• To investigate the interaction of a 4 keV proton with an isolated DNA base pair (bp) using computational methods.
• To analyze the dynamics of DNA dissociation and damage mechanisms under proton impact.

Main Methods:

• Time-dependent density functional theory (TD-DFT) was employed.
• Ehrenfest dynamics simulations were performed to model the system's evolution up to 193 fs.
• The effect of DNA base pair linkage was simulated by fixing O3' atoms.

Main Results:

• Proton impact leads to DNA base pair dissociation between 80 and 100 fs.
• A central impact (17.9 eV) caused base damage, leaving the backbone intact.
• A phosphate group impact (60 eV) resulted in backbone breakage and base damage.
• All atoms in the system were perturbed, indicating a widespread effect of the collision.

Conclusions:

• DNA base damage consistently accompanies backbone breaks due to weaker base-pairing hydrogen bonds.
• The study provides insights into the initial stages of radiation-induced DNA damage.
• Findings are relevant for radiation protection and targeted therapies involving charged particles.