Type IC topoisomerase (also called Topoisomerase V) has been identified. While it is structurally unique from type IA and IB topoisomerases, It shares a similar mechanism with type IB topoisomerase. A type II topoisomerase cuts both strands of one DNA double helix, passes another unbroken DNA helix through it, and then re-ligates the cut ...
Type II topoisomerases cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils.They use the hydrolysis of ATP, unlike Type I topoisomerase.In this process, these enzymes change the linking number of circular DNA by ±2.
It is a weak topoisomerase II inhibitor and forms stable DNA adducts through alkylation with specificity for DNA hypermethylated sites. S1223: Epirubicin HCl. Epirubicin HCl, a semisynthetic L-arabino derivative of doxorubicin, is an antineoplastic agent by inhibiting Topoisomerase.
A nice clip i found on the mechanisms of action of topoisomerase 1 and 2.
Bacterial gyrase (topoisomerase II) and topoisomerase IV are the targets of two classes of antibiotic drugs: quinolones and coumarins. These antibiotics are used to treat an assortment of different diseases, such as pneumonia, tuberculosis and malaria, by inhibiting DNA replication in the bacteria responsible.
This inhibits the progression of the enzyme topoisomerase II, which relaxes supercoils in DNA for transcription. It stabilizes the topoisomerase II complex after it has broken the DNA chain for replication, preventing the DNA double helix from being resealed and thereby stopping the process of replication.
The main difference between Topoisomerase I and II is that topoisomerase I cut one strand of the DNA double helix whereas topoisomerase II cut both strands of the DNA double helix. Furthermore, topoisomerase I occurs in eukaryotes while topoisomerase II occurs in both eukaryotes and prokaryotes.
Anthracyclines are arguably topoisomerase II inhibitors, although medicinal chemists usually classify them separately. But inside the cell mechanism involve breaking DNA and stopping cell reproduction in the G2 stage of the cycle. Topoisomerase I inhibitors include camptothecin, topotecan, and irinotecan.
Topoisomerase II was shown to form crossover intermediates with DNA in a mechanism that involves clamping of the DNA. Although bulk assays demonstrated the existence of a long-lived intermediate between topoisomerases and plectonemes in the absence of ATP, analysis of the kinetics of clamp release using single molecule methods revealed a ...
topoisomerase IIs are the target of many drugs used in cancer therapy. One category of topoisomerase II inhibitors acts by stabilizing the covalently bound form of topoisomerase II with DNA, resulting in increased topoisomerase II-cross-linked DNA strand breaks. A second category of topoisomerase II inhibitors are referred to as catalytic ...