Figure 2.

Loading rate dependence of the unbinding forces for FITC-E2 wt and 4D5-Flu at 25°C. For each loading rate more than 100 unbinding events were recorded. The most probable unbinding force was determined by fitting a Gaussian to the distribution of unbinding forces. The statistical error of the unbinding force was estimated as the width of the distribution divided by the square root of the number of unbinding events. The off-rates at zero force, determined from linear fits to the data, agree well with the thermal off-rate, which are indicated by arrows. At zero force Eq. 2 gives a value for r = k_off⋅k_B⋅T/x_β, allowing the placement of the kinetic constants on the r axis.