Enzyme (= gyrase in prokaryocytes) that changes the topology of DNA molecules. In every cell there are topoisomerases that unwind or relax the DNA by changing the number of turns of the DNA. This is particularly important in the replication or tangling of DNA. The topoisomerase thus prevents the DNA from becoming tangled during opening, transcription and closing. Topoisomerases hydrolyze phosphodiester bonds. Their molecular structure can accommodate a DNA double helix.
Topoisomerase
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There are several types of topoisomerase:
- Topoisomerase I leads to energy-independent single-strand breaks.
- Topoisomerase II (gyrase) causes ATP-dependent double-strand breaks.
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Topoisomerase inhibitors (e.g. irinotecan, topotecan, etoposide) are used as chemotherapeutic agents for the treatment of cutaneous lymphomas, metastasized melanomas and metastasized Merkel cell carcinomas, among others.
LiteratureThis section has been translated automatically.
- Lim DS et al (2003) Topoisomerase I inactivation by reticulol and its in vivo cytotoxicity against B16F10 melanoma. Chemotherapy 49: 257-263