The strength of a protein-based materials like spider silk lies in the specific geometric configuration of structural proteins, which have small clusters of weak hydrogen bonds that work cooperatively to resist force and dissipate energy. This video shows the failure of a beta-sheet model system under shear loading. As the middle strand is pulled with a constant speed, the rupture of hydrogen bonds in clusters leads to failure of the beta-sheet assembly. To read about this research by Professor Markus Buehler and Sinan Keten, visit this page http://cee.mit.edu/news/releases/2008/protein . Video / Sinan Keten