Figure 2 - Checks of equilibrium adsorption and failure of WLC on short length scales.

a,b, Plots of (R_s,s +L)² and cos _s,s +L from experimental data (dots), together with model-independent predictions assuming  = 54 nm (curves). c, Dots: negative logarithm of the observed probability distribution function G(; L = 5 nm), a measure of the effective bending energy at this length scale in units of k_BT. The graph is a histogram, computed using experimentally observed DNA contours with total length of about 240,000 nm, or a total of about 94,000 pairs of tangent vectors. The error bars represent expected n error in bin populations due to finite sample size. Dashed curve: the same quantity for curves drawn from the distribution appropriate to the WLC with persistence length equal to that used to draw the curves in (a and b). Although the two distributions agree qualitatively at low deflection , they disagree at large angles: the WLC model predicts far fewer such large deflections than were observed. Solid black curve: the same quantity when a sample of WLC configurations was generated numerically and converted to simulated AFM data, then subjected to the same image analysis that yielded the experimental dots.