Related Experiment Videos
Two subforms of eukaryotic topoisomerase I. Purification and structure-function relationships
A R Kudinov1, I B Bronstein, A G Gabibov
1Engelhardt Institute of Molecular Biology, Academy of Sciences of Russia, Moscow.
FEBS Letters
|December 21, 1992
Summary
A novel HPLC method purifies eukaryotic topoisomerase I (topo I) and reveals two distinct low-molecular-weight subforms. These subforms exhibit unique properties, including differing activities and sensitivities, suggesting structural variations.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Eukaryotic topoisomerase I (topo I) is crucial for DNA replication and transcription.
- Understanding topo I heterogeneity is essential for comprehending its diverse cellular roles.
Purpose of the Study:
- To develop a novel method for isolating and characterizing eukaryotic topoisomerase I.
- To investigate the potential existence of distinct topo I subforms.
Main Methods:
- High-performance liquid chromatography (HPLC) was employed for quantitative purification of topo I.
- Isoelectric focusing was used to differentiate enzyme fractions.
- Enzyme activity assays, camptothecin sensitivity tests, and proteolytic digestion mapping were performed.
Main Results:
- A new HPLC method successfully isolated high molecular weight topo I and two distinct low molecular weight fractions.
- These fractions displayed different isoelectric points, suggesting they are separate subforms.
- Significant differences were observed in specific activities, camptothecin sensitivity, and proteolytic digestion patterns between the subforms.
Conclusions:
- The developed HPLC method enables efficient purification of eukaryotic topo I and its subforms.
- Evidence supports the existence of at least two structurally and functionally distinct subforms of topoisomerase I.
- These findings contribute to a deeper understanding of topoisomerase I heterogeneity and its functional implications.