Stochastic motions in active networks formed by Actin and Myosin

本论文的重点是研究肌球蛋白和丝状肌动蛋白形成的混合网络的随机动力学。这些网络是细胞骨架的体外模型。此外，它们是一类新材料的成员，即所谓的热平衡之外的活性介质。噪声分析允许对基本非平衡过程的性质有价值的见解（例如活性膜的电噪声分析）。我们期望得出关于肌动球蛋白复合物的速度、幅度和个别功率冲程的速率的结论，以及不同功率冲程之间的相关性的表征。实验技术（准弹性光散射）允许调查的随机动力学的时间间隔范围从100纳秒至100毫秒，而不施加外力的肌动球蛋白复合物。因此，该技术非常适合本研究。由于肌球蛋白结合肌动蛋白丝的机械性能的变化可以被检测到。将使用特定的胶体探针来分离肌球蛋白和肌动蛋白对样品整体动力学的贡献。光散射实验将伴随荧光标记蛋白质的长程扩散测量和肌动蛋白滑行体外运动测定。

The focus of this proposal is the study of the stochastic dynamics of mixed networks formed by myosin and filamenteous actin. These networks are in vitro models for the cellular cytoskeleton. Moreover, they are members of a new class of materials, so-called active media which are outside of the thermal equilibrium. Noise analysis allows valuable insights into the nature of the elementary non-equilibrium process (e.g. analysis of the electric noise of active membranes). We expect conclusions about speed, amplitude, and rate of individual power strokes of actomyosin complexes as well as a characterization of the correlation between different power strokes. The experimental technique (quasi-elastic light scattering) allows an investigation of the stochastic dynamics in a time interval ranging from 100 nsec to 100 msec without the application of external forces on the actomyosin complex. Thus the technique is ideally suited for this study. Changes of the mechanical properties of actin filaments due to myosin binding can be detected. Specific colloidal probes will be used to separate the contributions of myosin and actin to the overall dynamics of the sample. The light scattering experiments will be accompanied by long range diffusion measurements of fluorescence labelled proteins and actin gliding in vitro motility assays.