FIGURE 5.

Example of the measured rupture force and loading rate distributions for the 30-basepair duplex. (a) Histogram of the unbinding forces of DNA30s. The histogram (FWHM = 14.2 pN) contains ∼860 rupture events and exhibits rupture forces above the B-S transition of 65 pN. The histogram is fitted with the calculated probability density function p(F) (black) with Δx = 4.4 nm and k_off = 7 × 10⁻²⁸ s⁻¹. To consider the detection noise, the probability density function was convolved with a Gaussian distribution. The standard deviation of the Gaussian distribution equals the typical noise value of the cantilever that was used (4.7 pN). (b) Histogram of the loading rates of DNA30s. The obtained loading rate distribution, plotted logarithmically, is compared with the calculated probability density function (black).