Biomimetic systems that are composed of rigid polymers or filaments and crosslinking molecules can be used to assemble filament networks and bundles. The bundles represent 'nanoropes' and exhibit material properties that are primarily determined by the number of plaited filaments. Scientists at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany have now shown that this assembly of filaments into bundles is prevented by the thermal motion of the filaments, unless the crosslinker concentration exceeds a certain threshold value. The latter value depends on the number of filaments, but remains finite in the limit of a large filament number. As the crosslinker concentration is lowered, the bundles may segregate into small sub-bundles, or undergo abrupt unbinding transitions. (Physical Review Letters 95, 038102, July, 2005).
Biological cells are mechanically stable because they contain actin filaments and microtubules that form networks and bundles. These filament architectures are determined and controlled by crosslinking proteins, which have two sticky ends that bind to different filaments. In order to understand the underlying forces and to optimise the mechanical properties of these architectures, one must study biomimetic model systems that are solely composed of filaments and crosslinking proteins. One important example is the assembly of several filaments into thick bundles or 'nanoropes'TM that are more rigid, and sustain a larger external load, than single filaments.
The assembly of filaments by molecular crosslinkers is disturbed by the thermal motion of the filaments. Scientists at the Max Planck Institute of Colloids and Interfaces have now shown that this thermal motion prevents filament assembly unless the crosslinker concentration exceeds a certain threshold value. The latter value depends on the filament rigidity, on the binding energy of the crosslinkers, and on the temperature. Furthermore, the threshoPage: 1 2 Related biology news :1
Contact: Dr. Jan Kierfeld
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