When a single DNA molecule is stretched beyond its normal contour length, a force-induced melting transition is observed. Ethidium binding increases the DNA contour length, decreases the elongation upon melting, and increases the DNA melting force in a manner that is consistent with the ethidium-induced changes in duplex DNA stability known from thermal melting studies. The DNA stretching curves map out a phase diagram and critical point in the force-extension- ethidium concentration space. Intercalation occurs between alternate base pairs at low forces and between every base pair at high forces.
|Original language||English (US)|
|Journal||Physical review letters|
|State||Published - Oct 7 2005|