Author response image 1. Average preferred crossing angle for topo VI obtained from comparisons among all right handed crossings and all left handed crossings for single-crossing relaxation experiments.

Each point represents the average crossing angle obtained by comparing the relative relaxation times and simulated DNA crossing angle distributions of 26 single-crossing measurements (13 of each handedness) with measurements from one DNA tether, plotted as a function of the average imposed crossing angle of the tether geometry to which the other measurements were compared. The error bars correspond to the SEM. The average preferred crossing angle computed from these cross-comparisons is 86.1 ± 0.5°.