Simplification of DNA Topology Below Equilibrium Values by Type II Topoisomerases by Valentin V. Rybenkov, Christian Ullsperger, Alexander V. Vologodskii, and Nicholas R. Cozzarelli Science Volume 277(5326): August 1, 1997 Published by AAAS

Figure 1 Generation of topological equilibria in circular DNA. During the random cyclization of a linear duplex DNA with cohesive ends (circle and caret), a population of numerous topologically distinct species is formed. Valentin V. Rybenkov et al. Science 1997;277: Published by AAAS

Figure 2 Type II topoisomerases remove topological links from DNA to levels below equilibrium. Valentin V. Rybenkov et al. Science 1997;277: Published by AAAS

Figure 3 Correlation between preferential decatenation, unknotting, and relaxation in topo II catalyzed reactions. Valentin V. Rybenkov et al. Science 1997;277: Published by AAAS

Figure 4 A three-binding-sites model of type II topoisomerase action. Valentin V. Rybenkov et al. Science 1997;277: Published by AAAS