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APS » Journals » Phys. Rev. Lett. » Volume 95 » Issue 15
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Phys. Rev. Lett. 95, 158102 (2005) [4 pages]

Mapping the Phase Diagram of Single DNA Molecule Force-Induced Melting in the Presence of Ethidium

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Ioana D. Vladescu1, Micah J. McCauley1, Ioulia Rouzina2,*, and Mark C. Williams1,3,*
1Department of Physics, Northeastern University, 111 Dana Research Center, Boston, Massachusetts 02115, USA
2Department of Biochemistry Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA
3Center for Interdisciplinary Research on Complex Systems, Northeastern University, 111 Dana Research Center, Boston, Massachusetts 02115, USA

Received 5 April 2005; published 6 October 2005

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.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.95.158102
DOI:
10.1103/PhysRevLett.95.158102
PACS:
87.14.Gg, 64.60.−i, 82.39.Pj

*Corresponding authors.

 
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