Figure 1 shows multiple force-distance curves obtained by a single Talin protein submitted to alternating stretching and relaxation cycles using AFS. Figure 2 displays an enlarged snippet of an individual force-distance curve corresponding to a single pulling cycle. Here, while ramping the force from 15 to 19 pN, we observe a series of four unfolding events — corresponding to four individual protein domains —ranging between 30 and 100 nm. The unfolding events can be clearly distinguished owing to the high-resolution distance measurement capability of this technology.
Figure 3 shows an illustration of a typical protein unfolding experiment performed at a constant force. Equilibrium dynamics show the transition between different intermediate states. AFS has the ability to measure equilibrium dynamics because the intrinsic force clamp drives the piezo at a constant voltage. Additionally, AFS allows measuring many molecules in parallel, which boosts the experimental data throughput.