Figure 5.

Schematic representation of the proposed model of the mechanical properties of A-tracts. (A) In the absence of stretching forces, molecules containing phased A-tracts (blue regions) appear largely bent as a consequence of the local structural bends. (B) Forces smaller than 10 pN align and straighten the bends along the pulling coordinate, which results in a significant deviation of the force-extension curves from the WLC model. (C) At forces larger than 10 pN, the bends are fully extended and the local elastic response of A-tracts, is exposed. This force regime unveiled the extraordinary enthalpic rigidity of A-tracts.