DNA topoisomerases are enzymes that regulate the topology of DNA by breaking and rejoining the phosphodiester backbone of the DNA molecule. These enzymes play a critical role in DNA replication, transcription, and repair by relieving the torsional stress that is generated during these processes. There are two main classes of DNA topoisomerases: type I and type II.
![(19S)-7-bromo-19-ethyl-19-hydroxy-10-methyl-17-oxa-3,6,13-triazapentacyclo[11.8.0.02,11.04,9.015,20]henicosa-1(21),2,4,6,8,10,15(20)-heptaene-14,18-dione - , used for , CAS No. S608836, by Aladdin Scientific](https://media-prod.aladdinsci.com/media/catalog/product/cache/5a65292c9ea620f6e55f72f0a2fa59fb/s/j/sj_500_S608836.jpg)
![(5S)-5-ethyl-5-hydroxy-7,18,20-trioxa-11,24-diazahexacyclo[11.11.0.02,11.04,9.015,23.017,21]tetracosa-1(13),2,4(9),14,16,21,23-heptaene-6,10-dione - , used for , CAS No. 104155-89-7, by Aladdin Scientific](https://media-prod.aladdinsci.com/media/catalog/product/cache/5a65292c9ea620f6e55f72f0a2fa59fb/s/j/sj_500_S609359.jpg)
