标题： 交联生物聚合物束：交联可逆性导致协同结合/解离现象 显示英文标题

标题： Crosslinked biopolymer bundles: crosslink reversibility leads to cooperative binding/unbinding phenomena

摘要： 我们考虑一个由相互交联的丝状物组成的生物聚合物束。 这些交联是可逆的：它们可以动态地结合和分离相邻的丝状物对，这由结合焓控制。 该束受到弯曲变形，相应的交联分布被测量。 对于由两条丝状物组成的束，在增加弯曲幅度时，观察到一级相变。 这种转变是从由许多结合的交联紧密耦合的丝状物状态，转变为仅有少量结合交联的几乎独立的丝状物状态。 对于由多于两条丝状物组成的束，观察到一系列一级相变。 这些相变与低密度和高密度交联区域之间的界面形成有关。 结合伞采样蒙特卡罗模拟与解析计算，我们详细描绘了交联剪切与丝状物拉伸之间的竞争如何驱动这些相变。 我们还发现，当交联变软时，不会观察到集体行为：此时交联依次解离，导致平均交联密度平滑下降。 显示英文摘要

摘要： We consider a biopolymer bundle consisting of filaments that are crosslinked together. The crosslinks are reversible: they can dynamically bind and unbind adjacent filament pairs as controlled by a binding enthalpy. The bundle is subjected to a bending deformation and the corresponding distribution of crosslinks is measured. For a bundle consisting of two filaments, upon increasing the bending amplitude, a first-order transition is observed. The transition is from a state where the filaments are tightly coupled by many bound crosslinks, to a state of nearly independent filaments with only a few bound crosslinks. For a bundle consisting of more than two filaments, a series of first-order transitions is observed. The transitions are connected with the formation of an interface between regions of low and high crosslink densities. Combining umbrella sampling Monte Carlo simulations with analytical calculations, we present a detailed picture of how the competition between crosslink shearing and filament stretching drives the transitions. We also find that, when the crosslinks become soft, collective behavior is not observed: the crosslinks then unbind one after the other leading to a smooth decrease of the average crosslink density.