Left-handed deoxyribonucleic acid double helix in solution

Area of Science:

• Biophysics
• Computational Chemistry
• Molecular Biology

Background:

• The conformation of synthetic deoxyribonucleic acid (DNA) double helices can vary depending on environmental conditions.
• Understanding DNA structure is crucial for comprehending its biological functions and interactions.

Purpose of the Study:

• To calculate magnetic shielding constants for synthetic poly(dG-dC).poly(dG-dC) in both Z-DNA and B-DNA forms.
• To compare calculated values with experimental nuclear magnetic resonance (NMR) data to determine the DNA's solution conformation.
• To investigate the contributions of ring current effects and atomic magnetic anisotropy to magnetic shielding.

Main Methods:

• Calculation of magnetic shielding constants using atomic coordinates for Z-DNA and B-DNA structures.
• Inclusion of ring current effects and atomic magnetic anisotropy (diamagnetic and paramagnetic components) in calculations.
• Comparison of calculated magnetic shielding values with experimentally observed NMR shift data for poly(dG-dC).poly(dG-dC) in high salt solution.

Main Results:

• Calculated magnetic shielding constants showed strong agreement with experimental NMR data for the Z-DNA conformation.
• Calculated values for the B-DNA conformation exhibited significant deviation from experimental NMR data.
• The findings suggest that poly(dG-dC).poly(dG-dC) adopts a Z-DNA structure in high salt concentrations.

Conclusions:

• Synthetic poly(dG-dC).poly(dG-dC) favors the left-handed Z-DNA double helix conformation in high salt solutions.
• The study validates the use of magnetic shielding constant calculations to predict DNA solution structures.
• This work provides insights into the structural plasticity of synthetic DNA and its environmental response.