FIGURE 8:

Analysis of potential barrier energy landscapes and bond lifetimes by dynamic force spectroscopy (A) Dynamic force spectrum: Plot of most probable unbinding force (f* in Eq. 2) of α_IIBβ₃–integrin/RGD interactions vs. logarithm of loading rate, experimental data are shown as follows: red square (SNV activated integrin), blue circle (Mn²⁺-activated integrin), and open circle (low affinity integrin). Lines represent fits to Eq. 2. γ, the distance of the potential barrier position from the bottom of the potential well, is derived from the slope. The force-free dissociation rate, k⁰, is derived from the intercept of the fit. (B) Potential energy landscape of the α_IIBβ₃–^RGDP2Y₂R bond qualitatively showing the relative magnitudes of energy barrier widths of SNV (0.35 nm) and Mn²⁺- (0.40 nm) activated interactions derived from the DFS. k⁰ values for SNV and Mn²⁺-associated interactions were 0.13 s^–1 and 0.097 s^–1, respectively. (C) Effect of tensile force (f in Eq. 1) on the lifetime of the α_IIBβ₃-^RGDP2Y₂R interactions, for control and SNV- and Mn²⁺-treated samples. (D) Effect of tensile force on the potential energy barrier landscape of SNV- and Mn²⁺-treated integrin–^RGDP2Y₂R interactions (see the text for details). The mechanical energy for each applied force lowers the transition state energy barrier by -f•γ as shown.