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BP: Fachverband Biologische Physik

BP 2: Biopolymers and Biomaterials (joint session BP/CPP)

BP 2.3: Talk

Monday, March 23, 2009, 11:30–11:45, ZEU 260

A liquid state theory for biopolymers — •Jens Glaser and Klaus Kroy — Inst. f. Theoretische Physik, Universität Leipzig, PF 100920, 04009 Leipzig

Solutions of stiff biopolymers, e.g. F-actin, are unique in that the polymers are neither completely rigid nor completely flexible. A successful description of their equilibrium properties is based on the concept that hard-core interactions with the surrounding solution confine each polymer to an effective tube-like cage. The tube radius plays a central role for the phenomenology of stiff polymer solutions. Its scaling behavior with concentration as well as exact prefactors have been derived using mean-field theory and simulation. Generalizing Onsager's ansatz for hard cylinders, we propose a liquid state theory for stiff polymers and derive the fluctuations of the tube radius itself. We obtain length-dependent corrections to the mean-field result as well as a rigorous result for the second cumulant of the distribution of tube radii. The results compare favorably with new dynamical measurements on F-actin networks, obtained using confocal laser scanning microscopy.