The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.
A unit of topo I can relax 0.2 ug pGEM 5Z DNA in 30 min at 37oC. The enzyme is supplied at a nominal concentration of approximately 2 units/ul.
Quality Control Tests: 1. A test for nuclease contamination is carried out by assaying for the formation of linear KDNA and linear plasmid DNA. Incubation with KDNA or supercoiled pGEM 5Z DNA (4 hrs. at 37ºC in the presence of 10 mM MgCl2) is performed. Linear DNA or breakdown products are not generated under these conditions. 2. A check for cross contamination with Topo II is negative. There must be no decatenation of KDNA in topo II reaction conditions. 3. Performance in converting super-coiled DNA to relaxed DNA.
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Preparation and Storage
Stability and Storage
Shipped at 4°C. Upon delivery aliquot and store at -20°C or -80°C. Avoid repeated freeze / thaw cycles.
10 mM Tris-Cl, pH 7.5, 100 mM NaCl, 100 mM imidazole, 0.5 mM PMSF, 1 mM DTT, and 10 % glycerol
This product is an active protein and may elicit a biological response in vivo, handle with caution.
DNA topoisomerase 1
DNA topoisomerase I
NUP98 fusion gene
Topoisomerase (DNA) I
Type I DNA topoisomerase
FunctionThe reaction catalyzed by topoisomerases leads to the conversion of one topological isomer of DNA to another.
Involvement in diseaseNote=A chromosomal aberration involving TOP1 is found in a form of therapy-related myelodysplastic syndrome. Translocation t(11;20)(p15;q11) with NUP98.
Sequence similaritiesBelongs to the eukaryotic type I topoisomerase family.
Post-translational modificationsSumoylated. Lys-117 is the main site of sumoylation. Sumoylation plays a role in partitioning TOP1 between nucleoli and nucleoplasm. Levels are dramatically increased on camptothecin (CPT) treatment.
Cellular localizationNucleus > nucleolus. Nucleus > nucleoplasm. Diffuse nuclear localization with some enrichment in nucleoli. On CPT treatment, cleared from nucleoli into nucleoplasm. Sumolyated forms found in both nucleoplasm and nucleoli.