Pathways of mechanical unfolding of FnIII10: Low force intermediates

We study the mechanical unfolding pathways of the FnIII(10) domain of fibronectin by means of an Ising-like model, using both constant force and constant velocity protocols. At high forces and high velocities our results are consistent with experiments and previous computational studies. Moreover, the simplicity of the model allows us to probe the biologically relevant low force regime, where we predict the existence of two intermediates with very close elongations. The unfolding pathway is characterized by stochastic transitions between these two intermediates. (C) 2010 American Institute of Physics. [doi:10.1063/1.3464476]