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Cu2+/+ cation coordination to adenine--thymine base pair. Effects on intermolecular proton-transfer processes
Marc Noguera1, Juan Bertran, Mariona Sodupe
1Departament de Química, Universitat Autónoma de Barcelona, Bellaterra 08193, Spain.
The Journal of Physical Chemistry. B
|March 25, 2008
Summary
Copper cations (Cu+ and Cu2+) influence DNA base pair proton transfer. Cu+ can induce spontaneous proton transfer in thymine, while Cu2+ causes oxidation, altering proton transfer pathways, especially in hydrated environments.
Area of Science:
- Computational Chemistry
- Biophysical Chemistry
- Molecular Biology
Background:
- Intermolecular proton transfer is crucial for DNA base pairing and genetic information stability.
- Metal cation interactions can significantly alter the electronic and structural properties of DNA bases.
- Understanding these interactions is key to comprehending DNA damage and repair mechanisms.
Purpose of the Study:
- To investigate the effects of copper cations (Cu+ and Cu2+) on proton-transfer processes in Watson-Crick adenine-thymine base pairs.
- To explore how cation coordination sites influence the stability of proton-transferred products.
- To examine the role of hydration and cation oxidation state on these processes.
Main Methods:
- Density Functional Theory (DFT) calculations were employed to model the cationized base pair systems.
- Studies focused on cation coordination to key sites: N7 and N3 of adenine, and O2 of thymine.
- Thermodynamic stability of single and double proton-transferred products was assessed.
Main Results:
- Cu+ coordination to adenine N7/N3 sites resulted in stable double proton transfer, similar to neutral systems.
- Cu+ interaction with thymine O2 induced spontaneous single proton transfer, potentially forming rare base forms.
- Cu2+ cations induced base pair oxidation, stabilizing distinct single proton-transfer products, with hydration significantly modulating these effects.
Conclusions:
- Copper cations, particularly Cu+, can significantly alter proton-transfer dynamics in DNA base pairs.
- The oxidation state of the copper cation and the presence of water molecules are critical factors influencing these alterations.
- These findings highlight the potential for metal ions to induce DNA base modifications and influence genetic stability.
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