Uhde Jorg, Feneberg Wolfgang, Ter-Oganessian N, Sackmann Erich, Boulbitch Alexei
Department für Biophysik E22, Technische Universität München, James-Franck-Strasse, Germany.
Phys Rev Lett. 2005 May 20;94(19):198102. doi: 10.1103/PhysRevLett.94.198102. Epub 2005 May 17.
In studying a magnetic bead's creep response to force pulses in an entangled actin network we have found a novel regime where the bead motion obeys a power law x(t) approximately t(1/2) over two decades in time. It is flanked by a short-time regime with x(t) approximately t(3/4) and a viscous with x(t)approximately t. In the intermediate regime the creep compliance depends on the actin concentration c as c(-beta) with beta approximately 1.1 +/- 0.3. We explain this behavior in terms of osmotic restoring force generated by the piling up of filaments in front of the moving bead. A model based on this concept predicts intermediate x(t) approximately t(1/2) and long-time regimes x(t) approximately t in which the compliance varies as c(-4/3), in agreement with experiment.
在研究磁珠在缠结肌动蛋白网络中对力脉冲的蠕变响应时，我们发现了一种新的状态，即磁珠运动在两个数量级的时间内遵循幂律x(t)≈t^(1/2)。它的两侧分别是x(t)≈t^(3/4)的短时间状态和x(t)≈t的粘性状态。在中间状态下，蠕变柔量取决于肌动蛋白浓度c，呈c^(-β)形式，其中β≈1.1±0.3。我们用移动磁珠前方细丝堆积产生的渗透压恢复力来解释这种行为。基于这一概念的模型预测，中间状态下x(t)≈t^(1/2)，长时间状态下x(t)≈t，其中柔量随c^(-4/3)变化，与实验结果一致。
