Volume 78, Number 3, May 2007
Article Number 38001
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 11 April 2007
EPL, 78 (2007) 38001
DOI: 10.1209/0295-5075/78/38001

Radial distribution function for semiflexible polymers confined in microchannels

P. Levi and K. Mecke

Institut für Theoretische Physik, Universität Erlangen-Nürnberg - Staudtstraße 7, 91058 Erlangen, Germany

received 22 December 2006; accepted in final form 12 March 2007; published May 2007
published online 11 April 2007

An analytic expression is derived for the distribution $G(\vec{R}) $ of the end-to-end distance $\vec{R} $ of semiflexible polymers in external potentials to elucidate the effect of confinement on the mechanical and statistical properties of biomolecules. For parabolic confinement the result is exact, whereas for realistic potentials a self-consistent ansatz is applied, so that $G(\vec{R}) $ is given explicitly even for hard-wall confinement. The theoretical result is in good quantitative agreement with fluorescence microscopy data for actin filaments confined in rectangularly shaped microchannels. This allows an unambiguous determination of persistence length LP and the dependence of statistical properties such as Odijk's deflection length $\lambda $ on the channel width D. It is shown that neglecting the effect of confinement leads to a significant overestimation of bending rigidities for filaments.

87.15.-v - Biomolecules: structure and physical properties.
36.20.Ey - Conformation (statistics and dynamics).
05.20.-y - Classical statistical mechanics .

© Europhysics Letters Association 2007