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DNA topoisomerases from rat liver: physiological variations
Nucleic Acids Research
|February 25, 1983
Summary
A novel ATP-dependent DNA topoisomerase II (type II) was identified in rat liver nuclei. This enzyme
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Rat liver nuclei possess nicking-closing (topoisomerase I) activity.
- An additional ATP-dependent DNA topoisomerase activity (type II) was detected.
Purpose of the Study:
- To characterize the novel ATP-dependent DNA topoisomerase from rat liver nuclei.
- To investigate the enzyme's role in DNA replication.
Main Methods:
- Partial purification of the ATP-dependent DNA topoisomerase.
- In vitro assays for DNA catenation and decatenation.
- Measurement of topoisomerase I and II activities in rat liver nuclei during regeneration after partial hepatectomy.
Main Results:
- The partially purified enzyme exhibited ATP-dependent and magnesium-dependent DNA catenation and decatenation activities.
- The enzyme's requirements were consistent with eukaryotic type II topoisomerases.
- Topoisomerase I activity remained unchanged during liver regeneration.
- Topoisomerase II activity significantly increased during liver regeneration.
Conclusions:
- The identified enzyme is likely a eukaryotic type II topoisomerase.
- The increased activity of type II topoisomerase during liver regeneration suggests its involvement in DNA replication.