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August 2020

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Topoisomerase I Assay Kit Product Description

This kit contains reagents for routine detection of Top1 activity. DNA markers (included) allow unequivocal detection of the enzyme. The assay is specific for topoisomerase I; (eukaryotic type II topoisomerases require MgCl2 and ATP). The standard topo I assay kit is supplied with EDTA containing reaction buffer (minus Mg++) in order to prevent nucleolytic nicking of the supercoiled substrate (although we note that some eukaryotic type I activities are stimulated by Mg++). This assay will work even with crude extracts. A detailed manual of instruction (see link above) is included that describes how to run the gels to maximally resolve topoisomers for analysis of DNA unwinding.

Topoisomerase I Assay Kit Contents (representative for 100 assay kit size):

-100 Units Human Top1 Enzyme (available with catalog number TG1015-1A only)
-Supercoiled pHOT-1 DNA (25 µg in 100 µl TE buffer, or 0.25 µg/ul)
-Relaxed pHOT-1 DNA marker, relaxed by topo I (50 ul at 0.05 µg/ml in gel loading buffer)
-10X Topo I assay buffer (300 µl)
-5X Stop buffer/gel loading dye (600 µl)
-Detailed instruction manual
-Sample data and documentation of all controls

Reviews and Citations:

  • Dexheimer TS, Pommier Y: DNA cleavage assay for the identification of topoisomerase I inhibitors.  Nature 2008, 3(11): 1736-1750. doi:10.1038/nprot.2008.174
  • Zhang L, Sullivan P, Suyama J, et. al: Epidermal growth factor-induced heparanase nucleolar localization augments DNA topoisomerase I activity in brain metastatic breast cancer.  Molecular Cancer Research 2010, 8: 278-290. doi: 10.1158/1541-7786.MCR-09-0375
Shipping and Storage Instructions:

This kit is shipped at ambient temperature or on dry ice if purchased with enzyme. Store enzyme at -70° C. All other components may be stored at 4° C. Avoid frequent freeze/thaw cycles with the plasmid as this may contribute to DNA breakage.

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