(a) Data for kf from Figure 2a. To describe the force dependence of these rates, the Bell equation was used: where k is the force dependent rate, k0 is the unloaded rate, (F) is the applied force, (d) is the distance parameter indicating the force dependence of the transition, k is Boltzmann’s constant, and T is the absolute temperature. Because the data show increasing rates as the magnitude of the force increases under either positive or negative loads, the Bell equation was fitted to the kf values separately for assisting (negative) and hindering (positive) loads. For assisting loads k0 = 579 (369–789, 68% CI) s−1 and d = −1.47 (−1.84 – −1.06), 68% CI) nm, and for hindering loads k0 = 354 (127–581, 68% CI) s−1, d = 2.54 (1.90–3.18, 68% CI) nm. (b) Because kint shows a general trend of increasing rate as the load becomes more positive (more hindering load), the fit for kint was performed on positive and negative data but excluded the point at −4.5 pN. k0 = 256 (131–381, 68% CI) s−1, d = 1.18 (0.67–1.68, 68% CI) nm.