Definition of topoisomerase in English:

topoisomerase

nounˌtɒpəʊˈʌɪsəməreɪz-ˌrāz

Biochemistry

An enzyme which alters the supercoiled form of a DNA molecule.
〔生化〕拓扑异构酶
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.

Definition of topoisomerase in US English:

topoisomerase

noun-ˌrāz

Biochemistry

An enzyme which alters the supercoiled form of a DNA molecule.
〔生化〕拓扑异构酶
Example sentencesExamples
- 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.
- Topoisomerase III is a type I topoisomerase, acting on DNA that is negatively supercoiled and/or contains single-strand regions.
- Both topoisomerase I and RNA polymerase II reactivity occurs in the minor groove of 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.
- 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.
- Down-regulated topoisomerase II gene expression in etoposide-selected cells has also been shown to be associated with an increased rate of spontaneous polyploidization.
- AQ4 is a potent topoisomerase II inhibitor and DNA intercalator.
- These compounds stabilize and trap the topoisomerase I - DNA complex, preventing the religation step of the breakage/rejoining reaction mediated by the enzyme.
- The clastogenicity of topoisomerase inhibitors is believed to result from the transient stabilization of the topoisomerase enzyme with DNA during the catalytic cycle.
- 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.
- Among the genes affected by supercoiling are the topoisomerase genes.
- 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.
- Further, the broken site at the TT4 gene contained a potential topoisomerase I cleavage site.
- Taken together, these results indicate that the overexpression of the topoisomerase I gene causes DNA damage that is lethal only in the scaA - background.
- Finally, the in vivo catalytic activities of eukarytotic type IA topoisomerases, the topoisomerase III from various higher organisms may be related to their sequences.
- 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.
- 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.
- A heart-shaped molecular donut, the topoisomerase II dimer boasts an electropositive tunnel, the likely passage point for DNA.
- 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.

Origin

1970s: from Greek topos ‘place’ + isomer + -ase.

词汇	topoisomerase
释义	Definition of topoisomerase in English: topoisomerase nounˌtɒpəʊˈʌɪsəməreɪz-ˌrāz Biochemistry An enzyme which alters the supercoiled form of a DNA molecule. 〔生化〕拓扑异构酶 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. Definition of topoisomerase in US English: topoisomerase noun-ˌrāz Biochemistry An enzyme which alters the supercoiled form of a DNA molecule. 〔生化〕拓扑异构酶 Example sentencesExamples 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. Topoisomerase III is a type I topoisomerase, acting on DNA that is negatively supercoiled and/or contains single-strand regions. Both topoisomerase I and RNA polymerase II reactivity occurs in the minor groove of 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. 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. Down-regulated topoisomerase II gene expression in etoposide-selected cells has also been shown to be associated with an increased rate of spontaneous polyploidization. AQ4 is a potent topoisomerase II inhibitor and DNA intercalator. These compounds stabilize and trap the topoisomerase I - DNA complex, preventing the religation step of the breakage/rejoining reaction mediated by the enzyme. The clastogenicity of topoisomerase inhibitors is believed to result from the transient stabilization of the topoisomerase enzyme with DNA during the catalytic cycle. 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. Among the genes affected by supercoiling are the topoisomerase genes. 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. Further, the broken site at the TT4 gene contained a potential topoisomerase I cleavage site. Taken together, these results indicate that the overexpression of the topoisomerase I gene causes DNA damage that is lethal only in the scaA - background. Finally, the in vivo catalytic activities of eukarytotic type IA topoisomerases, the topoisomerase III from various higher organisms may be related to their sequences. 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. 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. A heart-shaped molecular donut, the topoisomerase II dimer boasts an electropositive tunnel, the likely passage point for DNA. 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. Origin 1970s: from Greek topos ‘place’ + isomer + -ase.
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