Agreement between single crystal X-ray and molecular mechanical sugar ring conformations

Area of Science:

• Computational chemistry
• Structural biology
• Biophysics

Background:

• Deoxyribose sugar conformation is crucial for DNA structure and function.
• Accurate modeling of sugar pucker requires precise force fields.

Purpose of the Study:

• To calculate deoxyribose sugar energy across a range of puckering parameters (q, W).
• To evaluate different force fields for their accuracy in modeling sugar ring conformations.
• To compare computational results with experimental X-ray diffraction data.

Main Methods:

• Energy minimization of deoxyribose structures with varying puckering parameters (q, W).
• Calculation of intra-ring bond lengths, angles, and dihedral angles.
• Comparison of calculated structures with 224 DNA single crystal X-ray structures.
• Utilized and modified Weiner's force field.

Main Results:

• A modified Weiner's force field demonstrated excellent agreement with experimental X-ray data.
• The calculated energy surface revealed a variable amplitude repuckering path.
• The average distortion observed was 0.42 Å.
• Experimental puckering parameters (q, W) largely fell within 1.0 Kcal/mol of the calculated minimum.

Conclusions:

• The modified Weiner's force field accurately predicts deoxyribose sugar conformations.
• Computational modeling provides a reliable method for studying DNA sugar pucker dynamics.
• Understanding sugar puckering is key to elucidating DNA structural variations.