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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 strands. Type II topoisomerases utilize ATP hydrolysis and are subdivided into two subclasses which possess similar structure and mechanisms:


DNA topoisomerase or simply Topoisomerase (EC, type I DNA topoisomerase, untwisting enzyme, relaxing enzyme, nicking-closing enzyme, swivelase, omega-protein, deoxyribonucleate topoisomerase, DNA gyrase) is an enzyme with systematic name DNA topoisomerase. This enzyme catalyzes the following chemical reaction. Forming a transient phosphodiester bond between a tyrosine residue in the ...


Topoisomerase II inhibitors can cause a wide range of chromosomal aberrations, and can act by either stabilising topoisomerase II-DNA complexes that are easily cleaved, or by interfering with the catalytic activity of the enzyme, both resulting in double-strand breaks in the DNA.


Topoisomerase definition is - any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule. any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule… See the full definition. SINCE 1828. Menu.


DNA Topoisomerase I. Topoisomerase I is a ubiquitous enzyme whose function in vivo is to relieve the torsional strain in DNA, specifically to remove positive supercoils generated in front of the replication fork and to relieve negative supercoils occurring downstream of RNA polymerase during transcription.


topoisomerase [to″po-i´so-mer-ās] an enzyme involved in mobilization and replication of DNA during cell division. to·po·i·so·mer·ase (tō'pō-i-som'ĕr-ās), A type of enzyme converting (isomerizing) one topologic version of DNA into another; acts by catalyzing the breakage and reformation of DNA phosphodiester linkages. [topo- + isomerase ...


Topoisomerase is a valuable enzyme for untangling supercoils and making space for new DNA strands to be created. Topoisomerase can both cleave DNA at a desired replication site and also ligate the ...


DNA Topoisomerase By Jennifer McDowall The DNA in the nucleus of a cell contains all the information it requires to carry out life’s processes: growth, development, maintenance, reproduction and protection. With all this information, it is no wonder that the length of a cell’s DNA is far greater than that of the cell compartment that contains it - the DNA in a single human diploid cell ...


DNA Topoisomerase. DNA Topoisomerases are a class of enzymes that release helical tension during transcription and replication, by creating nicks within the phosphate backbone on one or both strands of the DNA (Bermejo et al., 2007; Champoux, 2001; Deweese et al., 2008).


A nice clip i found on the mechanisms of action of topoisomerase 1 and 2.