Figure 3.

(A) Series of control experiments for different Ca²⁺ concentrations and sample substrates. The dissociation probability distributions are scaled for the absolute binding frequency. Experiments with Dsg2 modified AFM cantilever and sample substrate in 2 mM calcium-buffer (green) and EDTA-buffer (orange) expose a clear dependency of the binding frequency on the calcium concentration. The background of unspecific adhesion was tested in an experiment conducted on substrates lacking Dsg2 in calcium (red) and EDTA-buffer (gray). (B) Evolution of the Jarzynski equality. The exponentially averaged work $W_n$ plotted versus the number of dissociation events $n$. For wildtype Dsg2 and mutations thereof (green, red and yellow) measured in a 2 mM Ca²⁺ buffer-solution the Jarzynski equality converges fast yielding a robust estimate of the free energy difference $\mathrm{\Delta }{G}_0$. The evolution of $\mathrm{\Delta }{G}_0$ for wildtype Dsg2 (blue) in calcium-free EDTA-buffer solution does not converge for $n<2000$.