TOPOISOMERASE I

Topoisomerase I
Topoisomerase I (DNA-relaxing enzyme) catalyzes the removal of superhelical turns from covalently closed DNA by a transient breakage and rejoining of phosphodiester bonds. Topoisomerase I is active in the presence of EDTA.
Applications: Relaxing positively and negatively supercoiled DNA (1). Producing DNA topoisomers (2).
Source: Purified from calf thymus.
Performance and Quality Testing: Endodeoxyribonuclease, 3´ and 5´ exodeoxyribonuclease, and phosphatase assays; conversion of super-coiled DNA to relaxed DNA.
Unit Definition: One unit catalyzes the conversion of 0.5 µg of superhelical Φ X174 RF DNA to a relaxed state in 30 min. at 37°C.
Unit Reaction Conditions: 50 mM Tris-HCl (pH 7.5), 50 mM KCl, 10 mM MgCl2 , 0.1 mM EDTA, 0.5 mM DTT, 30 µg/ml/BSA, 0.5 µg
Φ X174 RF DNA, and enzyme in 50 µl for 30 min. at 37°C.
Enzyme: Topoisomerase
Product Size: 500 units 
Shipping Condition: Wet Ice 
Regulatory Statement: For Research Use Only. Not for use in diagnostic procedures.
Store in freezer (-5 to -30°C).