The linker region, consisting of two identical protein chains (indicated by the red and blue ribbons), in a full-atom representation. The central axis of the molecule is indicated (gray dashed line), as well as the direction of the torque τ and the pulling forces f. The residues at the top (red circles) are fixed to their position, and the torque and force are exerted on the residues at the bottom (blue circles). To see this figure in color, go online.