Topoisomerase 2 resolves hyperpositively supercoiled DNA before recombination forks and topoisomerase 3 resolves hypernegatively supercoiled DNA after recombination forks.

• 拓朴异构酶可以解开在重组叉之前高度正螺旋结构，拓朴异构酶3可以解开重组叉之后高度负螺旋结构。