非共价键合长丝的断裂和解聚
Fragmentation and depolymerization of non-covalently bonded filaments
摘要：
蛋白质分子通常通过非共价物理键自组装形成延伸的细丝，如淀粉样蛋白、F-肌动蛋白、中间细丝等。丝生长的动力学受到分解速率的限制，在该分解速率下，由于热运动，蛋白质间的键断裂。现有的模型通常假设亚基的热解离均匀地沿着细丝发生，或者甚至优先在中间发生，而众所周知的F-肌动蛋白从一端脱附的倾向是由生化因素介导的。在这里，我们显示了一个非常一般的（和通用的）模型，使用布朗动力学模拟和理论，沿长丝的分裂位置是强烈控制的约束力的最小值的不对称性，以及由长丝的弯曲刚度。我们提供了亚基之间的相互作用势和断裂拓扑结构的功能之间的基本连接。对于中心力（即完全柔性）键，断裂速率总是在链的中间最大，而对于半柔性或刚性长丝，该速率在中间或平坦处最小。新兴的框架提供了一个统一的理解生物聚合物的碎片和解聚，并恢复其不同的限制早期的结果。
英文摘要：
Protein molecules often self-assemble by means of non-covalent physical bonds to form extended filaments, such as amyloids, F-actin, intermediate filaments, and many others. The kinetics of filament growth is limited by the disassembly rate, at which inter-protein bonds break due to the thermal motion. Existing models often assume that the thermal dissociation of subunits occurs uniformly along the filament, or even preferentially in the middle, while the well-known propensity of F-actin to depolymerize from one end is mediated by biochemical factors. Here, we show for a very general (and generic) model, using Brownian dynamics simulations and theory, that the breakup location along the filament is strongly controlled by the asymmetry of the binding force about the minimum, as well as by the bending stiffness of the filament. We provide the basic connection between the features of the interaction potential between subunits and the breakup topology. With central-force (that is, fully flexible) bonds, the breakup rate is always maximum in the middle of the chain, whereas for semiflexible or stiff filaments this rate is either a minimum in the middle or flat. The emerging framework provides a unifying understanding of biopolymer fragmentation and depolymerization and recovers earlier results in its different limits.
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