Dresden 2009 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 2: Biopolymers and Biomaterials (joint session BP/CPP)
BP 2.2: Vortrag
Montag, 23. März 2009, 11:15–11:30, ZEU 260
End-monomer dynamics in semiflexible polymers — •Michael Hinczewski1,2, Xaver Schlagberger1, Michael Rubinstein3, Oleg Krichevsky4, and Roland R. Netz1 — 1Physics Dept., Technical Univ. of Munich, Germany — 2TUBITAK - Bosphorus Univ. Feza Gürsey Institute, Turkey — 3Dept. of Chemistry, Univ. of North Carolina, U.S.A. — 4Physics Dept., Ben-Gurion Univ., Israel
Precise experimental observations over the last few years of end-monomer dynamics in the diffusion of double-stranded DNA have given conflicting results: one study indicated an unexpected Rouse-like scaling of the mean squared displacement (MSD) ⟨ r2(t) ⟩ ∼ t1/2 at intermediate times, corresponding to fluctuations at length scales larger than the persistence length but smaller than the coil size; another study claimed the more conventional Zimm scaling ⟨ r2(t)⟩ ∼ t2/3 in the same time range. Spurred by this experimental controversy, we investigate the end-monomer dynamics of semiflexible polymers through Brownian hydrodynamic simulations and dynamic mean-field theory [1]. Both theory and simulation point to a novel intermediate dynamical regime where the effective local exponent of the end-monomer MSD, α(t) = dlog⟨ r2(t) ⟩ /dlogt, drops below the Zimm value of 2/3 for sufficiently long chains. The deviation from the Zimm prediction increases with chain length, though it does not reach the Rouse limit of 1/2. Anomalously low values of the effective exponent α are explained by hydrodynamic effects related to the slow crossover from dynamics on length scales smaller than the persistence length to dynamics on larger length scales. [1] arXiv:0809.0667, Macromolecules in press (2008).