Figure 4.

Secondary structure of α¹² in equilibrium and at a pulling force of 5 pN. (A) The α-helical conformation of α¹² along the sequence from the N- (bottom) to the C-terminal side (top) in five independent equilibrium simulations. (B) The α-helical conformation of α¹² in five independent FCMD simulations using a constant pulling force of 5 pN. (C) Percentage of α-helical residues in α¹² in equilibrium (black) and under force (red). (Inset, top) Helicity of α¹² in the second half of five independent simulations. (Inset, bottom) End-to-end distance of α¹² in the final 100 ns of five independent simulations. Secondary structure calculations have been done with DSSP (37). Applying a force of 5 pN moves the conformational ensemble of α¹² toward structures of higher helical content.