%0 Book Section %1 statphys23_0667 %A Guttmann, A.J. %A Jensen, I. %A Kumar, S. %A Jacobsen, J.L. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K curves finite-lattice force-extension interacting method protein saw statphys23 topic-10 unfolding %T Force induced biopolymer unfolding %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=667 %X Based on series expansions of unprecedented length, we study the unfolding of a two-dimensional polymer attached to a surface. The problem is modelled by an interacting self-avoiding walk (ISAW) $ Z^2$, with one end attached to the surface, and the other pulled, normal to the surface, with a force proportional to the perpendicular distance from the surface. We study the finite length partition function $$Z_N(F,T)=\sum_all \ saw w^m u^x = \sum_m,x C(N,m,x) w^m u^x,$$ where $C(N,m,x)$ is the number of ISAW of length $N$ having $m$ n-n contacts, and whose end-points are at a distance $x=x_N - x_0$ apart. Based on efficient finite-lattice method algorithms, extensive computer enumerations have provided data for chain lengths up to 55. A statistical mechanical description of flexible and semi-flexible polymer chains in a poor solvent is developed in the constant force and constant distance ensemble. We predict the existence of many intermediate states at low temperatures stabilised by the force. A uniform response to pulling and to compressing has been obtained in the constant distance ensemble. We show the signature of a cross-over length which increases linearly with chain length. Below this cross-over length, the critical force of unfolding decreases with temperature, while above it increases with temperature. For stiff chains, we find for the first time a ``saw-tooth'' like behaviour in the force-extension curves which has been seen earlier in the case of protein unfolding.

@incollection{statphys23_0667, abstract = {Based on series expansions of unprecedented length, we study the unfolding of a two-dimensional polymer attached to a surface. The problem is modelled by an interacting self-avoiding walk (ISAW) $ {\mathbb Z}^2$, with one end attached to the surface, and the other pulled, normal to the surface, with a force proportional to the perpendicular distance from the surface. We study the finite length partition function $$Z_N(F,T)=\sum_{all \ saw} w^m u^x = \sum_{m,x} C(N,m,x) w^m u^x,$$ where $C(N,m,x)$ is the number of ISAW of length $N$ having $m$ n-n contacts, and whose end-points are at a distance $x=x_N - x_0$ apart. Based on efficient finite-lattice method algorithms, extensive computer enumerations have provided data for chain lengths up to 55. A statistical mechanical description of flexible and semi-flexible polymer chains in a poor solvent is developed in the constant force and constant distance ensemble. We predict the existence of many intermediate states at low temperatures stabilised by the force. A uniform response to pulling and to compressing has been obtained in the constant distance ensemble. We show the signature of a cross-over length which increases linearly with chain length. Below this cross-over length, the critical force of unfolding decreases with temperature, while above it increases with temperature. For stiff chains, we find for the first time a ``saw-tooth'' like behaviour in the force-extension curves which has been seen earlier in the case of protein unfolding.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Guttmann, A.J. and Jensen, I. and Kumar, S. and Jacobsen, J.L.}, biburl = {https://www.bibsonomy.org/bibtex/2e0884f58f8ee6a0ca5c16b59e140036a/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {909b1ad8f3ce8ad836578c35c6b118f6}, intrahash = {e0884f58f8ee6a0ca5c16b59e140036a}, keywords = {curves finite-lattice force-extension interacting method protein saw statphys23 topic-10 unfolding}, month = {9-13 July}, timestamp = {2007-06-20T10:16:26.000+0200}, title = {Force induced biopolymer unfolding}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=667}, year = 2007 }