| Description |
Vaccinia virus Topoisomerase I is a type I eukaryotic topoisomerase that removes both positive and negative superhelical turns (right- and left-handed supercoils) from covalently closed DNA. The enzyme relaxes supercoiled DNA, resulting in covalently closed, circular DNA with reduced superhelicity. Unlike many topoisomerases, Vaccinia virus Topoisomerase I does not absolutely require Mg2+ for activity, although low concentrations of Mg2+ may enhance its function.
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| Applications |
- Studying the effects of DNA supercoiling on transcription in vitro
- Chromatin reconstitution assays
- Determining the degree of supercoiling of naturally occurring DNA
- Detection of mutant plasmids differing in length by a single base pair
- Enhancing restriction enzyme digestion of resistant DNA substrates by relaxing DNA to expose restriction sites
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| Source |
Recombinant protein expressed in E. coli carrying the Vaccinia virus H6R gene
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| Molecular Weight |
~32 kDa (monomer) |
| Unit Definition |
One unit of Vaccinia virus DNA Topoisomerase I will convert 1 µg of supercoiled DNA (Form I) to relaxed closed circular DNA (Form II) in 1 hour at 37 °C under standard assay conditions.
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| Components |
Vaccinia virus Topoisomerase I: 10,000 units/mL in 10 mM Tris-HCl, 1 mM DTT, 0.1 mM EDTA, 50% glycerol, pH 7.5 (at 25 °C)
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| Quality Control |
Free of detectable exo- and endodeoxyribonucleases, non-specific DNase, and RNase as confirmed by quality control assays.
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| Storage Condition |
-20 °C
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| References |
Shuman, S. "Vaccinia virus DNA topoisomerase I: a multifunctional enzyme." J Biol Chem. 1991; 266(30): 19162-19166.
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