Topoisomerase I Proteins and Enzymes

Topoisomerases are nuclear enzymes involved in a variety of cellular activities such as chromosome condensation, DNA replication, transcription, recombination and segregation at mitosis. Human topoisomerase I is a 100kD protein capable of relaxing positively and negatively supercoiled DNA by performing a transient single stranded nick which is then religated at the end of the reaction. It has been shown that the enzyme is located in regions of the genome that are undergoing active RNA ...