The pulling force of a single DNA molecule condensed by spermidine

In a recent experiment, a single DNA double helix is stretched and relaxed in the presence of spermidine, a short positive polyelectrolyte, and the pulling force is measured as a function of DNA extension. In a certain range of spermidine concentration, a force plateau appears whose value shows maxi...

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Bibliographic Details
Published in:Physica A 2005-04, Vol.349 (3), p.563-570
Main Authors: Zhang, Rui, Shklovskii, B.I.
Format: Article
Language:English
Subjects:
Condensation
DNA
Pulling force
Spermidine
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Summary:In a recent experiment, a single DNA double helix is stretched and relaxed in the presence of spermidine, a short positive polyelectrolyte, and the pulling force is measured as a function of DNA extension. In a certain range of spermidine concentration, a force plateau appears whose value shows maximum as a function of spermidine concentration. We present a quantitative theory of this plateau force based on the theory of reentrant condensation and derive almost parabolic behavior of the plateau force as a function of the logarithm of the spermidine concentration in the range of condensation. Our result is in good agreement with experimental data.
ISSN:0378-4371
1873-2119
DOI:10.1016/j.physa.2004.11.013