Faculty of Engineering and Natural Sciences
FENS MAT SEMINARS
Nanomechanics of Beta-Structures in Protein Materials
Department of Civil and Environmental Engineering
Massachusetts Institue of Technology
The ultrastructure of spider silk, muscle tissue or amyloid fibers consists primarily of regular beta-sheet secondary structures, stabilized by hierarchical assemblies of H-bonds. Despite the weak nature of H-bond interactions, these materials exhibit properties such as high strength to weight ratio, extensibility and robustness to material defects. However, the recipe for creating such fascinating materials that predominantly utilize weak interactions has so far remained a secret. In this talk, I’ll present some of our work on the mechanical properties of beta-structures, illustrating how full-atomistic modeling techniques can be combined with statistical mechanics and continuum approaches to shed light on elasticity, size-dependent strength and fracture processes in protein materials. The talk will summarize our work on silks, amyloids, and virulence factors such as the cell-puncture device of bacteriophage T4 virus, elucidating the influence of deformation rate and nano-scale confinement effects on mechanical behavior of polypeptide nanostructures employing H-bonds. Our strength and optimal size predictions explain recent proteomics data as well as AFM experiments, and lead to a key hypothesis: confined H-bond clusters are prevalent in alpha helices, beta-sheets and beta-solenoids, perhaps as an evolutionary design principle that derives from generic mechanical properties of the fundamental building blocks of life.
7 January 2009,
FENS G032 at 14.40