Stochastic motions in active networks formed by Actin and Myosin

• Applicant: Professor Dr. Rudolf Merkel
• Subject Area: Biophysics
• Term: from 1999 to 2002
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5174654

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.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1068: Molekulare Motoren