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单词 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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更新时间:2024/12/27 17:13:36