Figure 2. Mechanical unfolding of (M-crystallin)₈ using SMFS.

(A) A pair of typical single-molecule force extension (FX) traces of apo protein (black). A series of equidistant force peaks in FX traces indicating the sequential unfolding of individual M-crystallin units in the octamer during the mechanical stretching (pulling speed is 1000 nm/s). The unfolding force peaks in sawtooth pattern are fitted with WLC model (grey). The contour length change is ∼29 nm and the unfolding force is ∼90 pN. Histograms of contour length change fitted to Gaussian distribution (B) and unfolding force (C) are shown.