Regensburg 2004 – scientific programme

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PV: Plenarvorträge

PV IV

PV IV: Plenary Talk

Tuesday, March 9, 2004, 13:30–14:15, H1

Plateaus and Jumps in Single Molecule DNA Unzipping Experiments — •David R. Nelson — Lyman Laboratory of Physics and Division and Engineering and Applied Physics, Harvard Univeristy, Cambridge, MA 02138

We discuss the denaturation of long, double-stranded DNA pulled apart by a constant force. When the force approaches a critical threshold, a remarkable unzipping transition occurs which is strongly influenced by randomness in the base pair sequence.[1] The DNA unzips via a series of discrete jumps and plateaus which allow it to reach successively deeper energy minima. Above the threshold force, the dynamics of unzipping is related to that of a particle diffusing in a random force field. Recently, the first observations of this striking behavior, carried out on several identical molecules in parallel, have been reported.[2] The position and duration of the pauses in the separation are reproducible from molecule to molecule and depend on the applied force. For small forces, the DNA remains in a partially unzipped state. We expect similar energy landscapes together with anomalous drift and diffusion for certain molecular motors near the stall force.

[1] D. K. Lubensky and D. R. Nelson, Phys. Rev. E 65, 031917 (2002).

[2] C. Danilowicz et. al. Prod. Natl. Acad. Sci. 100, 1694 (2003).