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BP: Fachverband Biologische Physik
BP 11: Posters: Cytoskeleton
BP 11.10: Poster
Tuesday, April 1, 2014, 09:30–12:30, P1
Equilibrium Dynamics of Helical Polymers — •Lorenz Huber, Philipp Lang, and Erwin Frey — Arnold Sommerfeld Center for Theoretical Physics and Center for NanoScience, Department of Physics, Ludwig-Maximilians-Universität München, Germany
Biopolymers like DNA, cytoskeletal filaments or artificially designed DNA-origami fibres are elastic nanoparticles that form helical configurations in their ground state. The handedness, radius and pitch of these helices are determined by their curvature κ and torsion τ. Their statistical mechanics is described by the helical wormlike chain model, where κ,τ are identified as the filaments’ intrinsic bending and twisting rates, respectively.
Here we employ Brownian dynamics simulations to investigate the thermal end-to-end distance fluctuations. We find that ⟨δ R2(t)⟩ exhibits a rich scaling behavior with varying κ and τ. For κ=0 the initial relaxation resembles the t3/4-scaling law as predicted by semiflexible polymer theory. In contrast, helices with a low ascending pitch angle, i. e. κ>τ, show power law exponents exceeding 3/4 due to the additional elastic modes of the spring-like polymer conformation. The crossover region with κ<τ reveals a sudden intermediate relaxation regime with a scaling exponent well below 3/4. With rising τ this domain only slowly converges towards the semiflexible limiting case.
Our findings demonstrate the intriguing influence of helical parameters on the dynamics of single polymer systems and can in principle help to determine structural details beyond the resolution of (static) experimental techniques.