Proteins as molecular springs and elastic elements in biology

Mechanical forces are commonly found in nature, for example, during the incessant heart muscle contraction or in the remarkably strong spider webs. Proteins, the molecular work horses of biology, play the role of ‘molecular spring’ in these cases. The protein based molecular springs designed by nature not only survive high stretching forces without breaking apart but also respond in a reversible manner. Molecular level understanding of their mechanical response is beginning to emerge with the development of single-molecule techniques, such as the atomic force microscope (AFM) and optical tweezers. Both of these techniques probe the mechanical properties of proteins and measure forces that are required to induce a conformational change or unfolding when subjected to stretching. Furthermore, using polymer physics models, it is possible to quantify the mechanical response in terms of enthalpic and entropic elastic components. 
Despite the progress in experiments and computer simulations, the general rules that govern protein mechanical stability and folding need to be worked out in more detail and we are currently working towards this goal. In this talk, I will present our results on the mechanical stability and unfolding of model proteins that are structurally similar. Our experiments also show that it is possible to modulate the mechanical and unfolding properties of proteins with the help of small molecules and ions