PHYS 681 |
| Amit Meller1, Jerome Mathé1, Virgile Viasnoff1, and Yitzhak Rabin2. (1) Rowland Institute at Harvard, Harvard University, 100 Edwin Land Blvd., Cambridge, MA 02142, (2) Department of Physics, Bar-Ilan University, Ramat-Gan, 52900, Israel |
| Using the recently developed active voltage control method, the entry rate of polynucleotides into the nanometer scale α-Hemolysin pore, and the voltage pattern used to induce DNA unzipping, are independently controlled. This method makes it possible to study the unzipping kinetics of hundreds of individual DNA molecules in a time-efficient manner. Specifically, we characterized the unzipping kinetics of 10 basepair DNA hairpins under constant voltage amplitudes or stationary voltage ramps (“loading rate”, R). We find that the nanopore unzipping of DNA does not fit to a single-step kinetics model, even at the limit of short hairpins. Instead, our data concur with, at minimum, a two-step kinetics model, which includes the thermally activated opening of ~5 base pairs. Our dynamic force spectroscopy measurements are in agreement with the ~log(R) dependence of the critical unzipping force, at high R values, observed by other methods, and reveal a weaker dependence on R for smaller forces. |
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Biophysical Chemistry and Novel Imaging of Single Molecules and Single Cells
8:20 AM-12:00 PM, Thursday, August 26, 2004 Pennsylvania Convention Center -- 103B, Oral
Division of Physical Chemistry |