Definition of topoisomerase in English:
topoisomerase
nounˌtɒpəʊˈʌɪsəməreɪz-ˌrāz
Biochemistry An enzyme which alters the supercoiled form of a DNA molecule.
Example sentencesExamples
- The clastogenicity of topoisomerase inhibitors is believed to result from the transient stabilization of the topoisomerase enzyme with DNA during the catalytic cycle.
- Taken together, these results indicate that the overexpression of the topoisomerase I gene causes DNA damage that is lethal only in the scaA - background.
- These compounds stabilize and trap the topoisomerase I - DNA complex, preventing the religation step of the breakage/rejoining reaction mediated by the enzyme.
- Since topoisomerase activity is needed for replication, inhibition of topoisomerases might prevent replication in irradiated S phase cells, avoiding DNA synthesis upon a damaged template.
- A heart-shaped molecular donut, the topoisomerase II dimer boasts an electropositive tunnel, the likely passage point for DNA.
- DNA topoisomerase I may play a major role in transcription; the enzyme is physically associated with actively transcribed regions of chromatin where it reduces torsional stress generated during transcription.
- Both topoisomerase I and RNA polymerase II reactivity occurs in the minor groove of DNA.
- Finally, the in vivo catalytic activities of eukarytotic type IA topoisomerases, the topoisomerase III from various higher organisms may be related to their sequences.
- In certain cases, the combination of a helicase and a topoisomerase provides a unique biological function and the interaction between the two is evolutionarily conserved.
- Among the genes affected by supercoiling are the topoisomerase genes.
- Recent studies in Xenopus have shown a role for DNA replication in the recruitment of topoisomerase II to the chromosomes to facilitate condensin assembly and condensation.
- Down-regulated topoisomerase II gene expression in etoposide-selected cells has also been shown to be associated with an increased rate of spontaneous polyploidization.
- Further, the broken site at the TT4 gene contained a potential topoisomerase I cleavage site.
- Topoisomerase III is a type I topoisomerase, acting on DNA that is negatively supercoiled and/or contains single-strand regions.
- AQ4 is a potent topoisomerase II inhibitor and DNA intercalator.
- This study illuminates some of the similarities and differences in the topoisomerase / DNA complex in eukaryotes and prokaryotes.
- DNA topoisomerase II is an essential cellular enzyme that functions in the segregation of chromosome pairs and in chromosome condensation.
- An in vitro study showed that the collision between a moving replication fork and a stalled topoisomerase can convert the complex to a nonreversible form.
- The value for the ancestor was expressed relative to the midpoint topoisomer of plasmid that was completely relaxed by using calf-thymus topoisomerase I and assigned = 0.
- Irinotecan is a camptothecin analogue that acts through the inhibition of a DNA unwinding enzyme, topoisomerase I, resulting in replication arrest with breaks in single strand DNA.
Origin
1970s: from Greek topos 'place' + isomer + -ase.