Direct observation of the tube model in F-actin solutions: Tube dimensions and curvatures

¹  Institute of Bio- and Nanosystems 4: Biomechanics, Research Centre Jülich - 52425 Jülich, Germany, EU
²  Marian Smoluchowski Institut of Physics, Jagiellonian University Kraków - Reymonta 4, 30-059 Kraków, Poland, EU
³  Arnold Sommerfeld Center for Theoretical Physics and Center for Nanoscience, Ludwig-Maximilians-Universität München, 80333 Munich, Germany, EU
⁴  Laboratory of Molecular Dynamics, Brain Science Institute, RIKEN - Wako, Saitama 351-0198, Japan

Corresponding author: r.merkel@fz-juelich.de

Received: 8 December 2008
Accepted: 18 March 2009

Abstract

Mutual uncrossability of polymers generates topological constraints on their conformations and dynamics, which are generally described using the tube model. We imaged confinement tubes for individual polymers within a F-actin solution by sampling over many successive micrographs of fluorescently labeled probe filaments. The resulting average tube width shows the predicted scaling behavior. Unexpectedly, we found an exponential distribution of tube curvatures which is attributed to transient entropic trapping in network void spaces.