  DNA is structurally and mechanically altered by the binding of intercalator
molecules. Intercalation strongly affects the force-extension behavior of DNA,
in particular the overstretching transition. We present a statistical model
that captures all relevant findings of recent force-extension experiments. Two
predictions from our model are presented. The first suggests the existence of a
novel hyper-stretching regime in the presence of intercalators and the second,
a linear dependence of the overstretching force on intercalator concentration,
is verified by re-analyzing available experimental data. Our model pins down
the physical principles that govern intercalated DNA mechanics, providing a
predictive understanding of its limitations and possibilities.
