Figure 2.

Force–extension relationships for recombinant poly(I27) measured with AFM techniques. (A and B) Stretching of single I27^GLG₁₂ (A) or I27^RS₈ polyproteins (B) give force–extension curves with a sawtooth pattern having equally spaced force peaks. The sawtooth pattern is well described by the WLC equation (continuous lines). (C) Unfolding force frequency histogram for I27^RS₈. The lines correspond to Monte Carlo simulations of the mean unfolding forces (n = 10,000) of eight domains placed in series by using three different unfolding rate constants, k_u⁰, an unfolding distance, Δx_u, of 0.25 nm, and a pulling rate of 0.6 nm/ms.