FIGURE 3.

Histograms of the unbinding forces of DNA duplexes with a heterogeneous (X)₃₀ and a repetitive (GT)₁₅ sequence measured at similar pulling speeds. The duplex with the repetitive sequence dissociates at markedly lower forces, although its binding energy equals the binding energy of the heterogeneous sequence. The force distribution of the repetitive DNA is detruncated at a force of 40 pN. This gives evidence for an additional unbinding path, which is favored if an external force is applied.