| Products | Human Topoisomerase II, Alpha from USB Corp. | |
| Company | USB Corp. | |
| Item | Human Topoisomerase II, Alpha | |
| Price | ||
| Description | Source: E. coli containing a clone of the human Topoisomerase II gene. Description:Topoisomerase II alters the topological state of nucleic acids by passing an intact DNA helix through a transient break which generates a separate DNA helix(1,2). As a result of its double-stranded DNA passage mechanism, the enzyme can relax negatively or positively supercoiled DNA, as well as catenate/decatenate or knot/unknot DNA molecules. Topoisomerase II has an absolute requirement for divalent cation and ATP (or dATP). Tested User Friendly Properties: Molecular Weight: 340,000 Da homodimer Optimum Temperature: 3037C Optimum pH: 7.9, rapidly loses activity below pH 7.5 Requirements for Divalent Cation: 5mM Mg2+ is optimum for catalytic activity and 5mM Ca2+ for DNA cleavage. Optimum ATP Concentration: 0.5 to 1.0mM Optimum Ion Strength: 100-170mM KCl/NaCl Inhibitors: N-ethylmaleimide, zinc, novobicin, coumermycin A1, etoposide, amsacrine Purity:Greater than 98% pure as determined by silver-stained SDS-PAGE. Free of contaminating exonucleases and endonucleases. Storage Buffer:15mM sodium phosphate (pH 7.1), 700mM NaCl, 0.1mM EDTA, 0.5mM DTT, 50% glycerol. Shipping and Storage: Shipped on dry ice. Store at -20C for frequent use. Store at -80C for long-term storage. Assay Conditions:The reaction mixture contains 10mM Tris-HCl, pH 7.9, 175mM KCl, 0.1mM EDTA, 5mM MgCl2, 2.5% glycerol, 0.5mM ATP. Unit Definition:One unit is the amount of enzyme required to fully relax 0.3 g (5nM) of negatively supercoiled pBR322 plasmid DNA in 30 minutes at 37C under the standard assay conditions. Concentration:20 units/l Tested User FriendlyTM Functional Test: Tested for activity in standard Topoisomerase II unit assay. Applications:*Relaxing negatively or positively supercoiled DNA. *Catenating or decatenating DNA. *Knotting or unknotting DNA. PROTOCOL FOR RELAXATION OF SUPERCOILED DNA: Topoisomerase II, Alpha and 10X Topoisomerase II Reaction Buffer (PN 73592) are functionally tested in the following protocol using 300 ng (0.1 pmol) pBR322 DNA at 30C. *Mix 10X Topo II Reaction Buffer 2 l Supercoiled DNA 0.11.0 pmol Topoisomerase II, Alpha 110 units H2O to 20 l *Mix and incubate at 3037C for 15 minutes. *Stop the reaction by the addition of 3 l of 7mM EDTA or by the addition of SDS to 1%. | |
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