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Updated: Aug 2, 2026
15:22
Nucleoside Triphosphates - From Synthesis to Biochemical Characterization
Published on: April 3, 2014
Base release in nucleosides induced by low-energy electrons: a DFT study
Xifeng Li1, Léon Sanche, Michael D Sevilla
1Department of Nuclear Medicine and Radiobiology, Faculty of Medicine, Université de Sherbrooke, Quebec, J1H 5N4, Canada.
Radiation Research
|June 29, 2006
Summary
Low-energy electrons weaken DNA and RNA bonds, promoting base release. While electron attachment significantly weakens the C(1)´-N bond, a moderate activation barrier suggests a controlled rate of base release from DNA.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Radiation Chemistry
Background:
- Low-energy electrons induce DNA/RNA damage via molecular bond fragmentation.
- Recent experiments show glycosidic bond cleavage in nucleosides by low-energy electrons.
Purpose of the Study:
- Theoretically investigate the C(1)´-N bond strength in nucleosides (dA, dC, dT) after electron attachment.
- Determine the thermodynamic favorability and kinetics of electron-induced base release.
Main Methods:
- Density Functional Theory (DFT) calculations.
- Comparison of bond dissociation energies for neutral and anionic nucleosides.
- Assessment of gas-phase and solvated environments.
Main Results:
- Excess electron attachment weakens the C(1)´-N bond by 61-83 kcal/mol.
- Gas-phase fragmentation is exergonic for dA and dT, endergonic for dC.
- Solvation increases exergonicity, making fragmentation favorable for all nucleoside anion radicals.
- Activation barrier for C(1)´-N bond breaking is approximately 20 kcal/mol.
Conclusions:
- C(1)´-N bond breaking is thermodynamically favorable in nucleoside anion radicals, both in gas and solvated phases.
- Low-energy electrons (1 eV) can induce spontaneous C(1)´-N bond cleavage.
- A moderate activation barrier suggests base release occurs at a modest rate from stable anion radicals on DNA at room temperature.
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