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Spin-spin coupling constants in [corrected] artificial DNA intercalated with silver cations: theoretical prediction
Małgorzata Kauch1, Magdalena Pecul
1Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warszawa, Poland.
Summary
This study calculates nuclear spin-spin coupling constants for silver cations in DNA, finding the (1)J((15)N,(109)Ag) coupling is robust against environmental changes. The findings align well with experimental values.
Area of Science:
- Computational chemistry
- Biophysical chemistry
- Nuclear magnetic resonance spectroscopy
Background:
- Nuclear spin-spin coupling constants provide insights into molecular structure and electronic interactions.
- Silver cations (Ag+) interaction with DNA is relevant for understanding metallodrugs and DNA structural modifications.
Purpose of the Study:
- To calculate and analyze the indirect nuclear spin-spin coupling constants of Ag+ in DNA imidazole rings.
- To investigate the influence of geometry, water, and stacking interactions on these coupling constants.
Main Methods:
- Density Functional Theory (DFT) with the zeroth-order regular approximation (ZORA) Hamiltonian for relativistic effects.
- Polarizable continuum model (PCM) and explicit water molecules to simulate solvent effects.
- Coupling energy density (CED) for visualizing coupling pathways.
Main Results:
- The computed (1)J((15)N,(109)Ag) coupling constant (85-105 Hz) closely matches the experimental value (approx. 92 Hz).
- This coupling constant shows minimal sensitivity to geometry deformations, solvent presence, and stacking interactions.
- A small coupling constant (approx. 1 Hz) was predicted for adjacent silver ions, likely of limited practical interest.
- The (2)J((15)N,(15)N) coupling constant was calculated to be approximately 2.5 Hz, indicating measurable magnitude.
Conclusions:
- The (1)J((15)N,(109)Ag) coupling constant is a stable and reliable NMR probe for Ag+ interaction with DNA.
- Computational methods, including DFT-ZORA, accurately predict these coupling constants.
- The study provides a foundation for further NMR investigations of metal-DNA interactions.
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