Topoisomerase I (Vaccinia)

Description:
Topoisomerase I, derived from Vaccinia virus, is a type I eukaryotic topoisomerase that removes both positive and negative superhelical turns (also called right- and left-handed supercoils) from covalently closed DNA. The product of the reaction is a covalently closed, circular DNA with fewer positive or negative superhelical turns. DNA Topoisomerase I does not absolutely require Mg2+ to function, although low concentrations of Mg2+ may increase activity. Ideal for relax positively and negatively supercoiled DNA in presence of EDTA.

Applications:

• Studying chromatin reconstitution in vitro
• Determining the degree of supercoiling ofnaturally occurring DNA
• Detecting mutant plasmids that differ inlength by only one base-pair
• Increasing restriction endonucleasedigestion of resistant DNA substrates by "unwinding" the DNA coils to expose restriction sites

Source:
Topoisomerase I, derived from Vaccinia virus, is a type I eukaryotic topoisomerase.

Unit Definition:
One unit of DNA Topoisomerase I, Vaccinia, 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.

Recommended Reaction Conditions:
37 °C for 30 minutes

Recommended Storage Conditions:
This product should be stored at -20°C. Avoid repeated freeze-thaw.

References:

1. Shuman, S. et al. (1989), PNAS. 86: 3489-3493.