The conformations and energetics of photodamaged DNA.

Energy minimization techniques are used in conjunction with the results of small molecule crystallographic studies on relevant compounds to propose structural models for photodamaged DNAs. Specifically, we present models both for a DNA molecule containing a psoralen photo-crosslink and for a DNA molecule containing a thymine photodimer. In both models, significant distortions of the nucleic acid helix are observed, including kinking and unwinding at the damage site and numerous changes in the backbone torsion angles relative to their standard conformations. Both the torsion angle geometries and the energetics of the models are presented in detail.