TY  - JOUR
VL  - 79
N1  - © 2009 American Physical Society
ID  - eprints1821
SN  - 1539-3755
PB  - American Physical Society
A1  - Morrison, Greg
A1  - Thirumalai, D.
N2  - We develop an analytical method for studying the properties of a noninteracting wormlike chain (WLC) in confined geometries. The mean-field-like theory replaces the rigid constraints of confinement with average constraints, thus allowing us to develop a tractable method for treating a WLC wrapped on the surface of a sphere, and fully encapsulated within it. The efficacy of the theory is established by reproducing the exact correlation functions for a WLC confined to the surface of a sphere. In addition, the coefficients in the free energy are exactly calculated. We also describe the behavior of a surface-confined chain under external tension that is relevant for single molecule experiments on histone-DNA complexes. The force-extension curves display spatial oscillations, and the extension of the chain, whose maximum value is bounded by the sphere diameter, scales as f?1 at large forces, in contrast to the unconfined chain that approaches the contour length as f?1?2. A WLC encapsulated in a sphere, that is relevant for the study of the viral encapsulation of DNA, can also be treated using the mean-field approach. The predictions of the theory for various correlation functions are in excellent agreement with Langevin simulations. We find that strongly confined chains are highly structured by examining the correlations using a local winding axis. The predicted pressure of the system is in excellent agreement with simulations but, as is known, is significantly lower than the pressures seen for DNA packaged in viral capsids.
Y1  - 2009/01//
KW  - PACS number(s): 87.15.A -
KW  -  82.35.Pq
KW  -  82.35.Gh
TI  - Semiflexible chains in confined spaces
AV  - public
JF  - Physical Review E
UR  - http://link.aps.org/doi/10.1103/PhysRevE.79.011924
ER  -