type II topoisomerases

BioMed Central | Full text | Characterisation of cytotoxicity and DNA damage induced by the topoisomerase II-directed bisdioxopiperazine anti-cancer agent ICRF-187 (dexrazoxane) in yeast and mammalian cells: "Type II topoisomerases are essential nuclear enzymes found in all living organisms [1]. Their basic role in cells is to catalyse the transport of one DNA double helix through a transient double strand break in another DNA molecule [2]. This activity helps relieve tensions built up in DNA during various DNA metabolic processes such as DNA replication, chromosome condensation and de-condensation, chromosome segregation and transcription [3]."