Modeling the mechanics of a DNA oligomer.

DNA stretching and strand separation have been studied by molecular mechanics using an oligomer which has been the subject of nanomanipulation experiments (Noy et al., Chem. Biol. 4, 519, 1997). Adiabatic mapping of conformational energy carried out as a function of stretching leads to force/extension curves in good correlation with the experimental results. Other types of deformation are also modeled and compared with the experimental results obtained on polymeric DNA. The results highlight overall similarities, but point to thermodynamic differences and also to local base sequence effects which can be expected to play an important role at the level of biologically induced structural deformations.