Configuration Transitions of Free Circular DNA System Induced by Nicks

Figure 6

Schematic of the configuration transition of the free circular DNA system under the influence of nicks. (a) Torsional energy of natural DNA with negative supercoil cannot be released and leads to configuration of intersecting state; (b) torsional energy of circular DNA can be partially released by a nick and the intersecting form of some DNA segments changes to the flat circular form; (c) torsional energy of free DNA system is progressively released by nicks; (d) torsional energy of free DNA system is completely released by nicks, and the intersecting form changes to the flat circular form.

(a)

(b)

(c)

(d)