Human Topoisomerase II alpha and beta
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Human Topoisomerase II Alpha
Human topoisomerase II alpha is prepared by overexpressing in baculovirus-infected insect cells (Spodoptera frugiperda) and purifying it by methods developed in-house.
The enzyme is supplied in Dilution Buffer.
Store at -80°C.
It is recommended that larger pack sizes (500U and above) of the enzyme are aliquoted to avoid repeated freeze-thaw cycles.
See technical documents below for more detailed information and lot specific activities.
Technical Documents
Human Topoisomerase II Beta
Human topoisomerase II beta is prepared by overexpressing in baculovirus-infected insect cells (Spodoptera frugiperda) and purifying it by methods developed in-house.
The enzyme is supplied at a concentration of 2-10 U/μl in Dilution Buffer.
Store at -80°C. (Stable for 3 months undiluted).
It is recommended that the enzyme is aliquoted to avoid repeated freeze-thaw cycles.
Technical Documents
Human Topoisomerase II Decatenation Assay Kits
These contain human topo II and the catenated kDNA substrate in addition to the Assay and Dilution buffers for decatenation reactions. 1 U of human topo II will decatenate 200 ng of kDNA when incubated in 1X Assay buffer in a total reaction volume of 30 µl at 37°C for 30 minutes. The kits are available with either the alpha or beta forms of the enzyme.
Technical Documents
Human Topoisomerase II Relaxation Assay Kits
These contain human topo II and the supercoiled DNA substrate in addition to the Assay and Dilution buffers for relaxation reactions. 1 U of human topo II will relax 0.5 µg supercoiled pBR322 DNA in 30 minutes at 37°C. The kits are available with either the alpha or beta forms of the enzyme.
Technical Documents
Human Topoisomerase II Assay Kits For Cell Extracts
These kits are designed for assaying cell extracts and partially purified fractions containing human topo II. They contain kDNA substrate, Assay buffer, Dilution buffer, decatenated and linear DNA markers and stop buffer / loading dye.
The kit components are based on the standard assay which contains 500 ng substrate DNA per assay.
Technical Documents
High / Medium-Throughput Assay Kit - Human Topoisomerase II
The kit is supplied with sufficient human topo II enzyme, plasmid DNA substrate, buffers and other assay components* for 100 assays. The enzyme is supplied at a concentration of 10 U/μl in Dilution Buffer. The kit is also supplied with sufficient wash buffers for one 96-well plate. These buffers are supplied as 20X concentrates and must be diluted with ultra pure water prior to use. The kits are available with either the alpha or beta forms of the enzyme.
More information about this assay can be found on the "Services" page under "High/Medium Throughput Assay".
Kit issued with limited licence for individual use only.
Patent held by Inspiralis Ltd., Norwich, Norfolk, UK. (Patent No. GB0424953.8, US7838230)
Technical Documents
Human Topoisomerase II alpha 453 subunit
Human topoisomerase II alpha amino acids 1-453. This contains the ATPase domain, the activity of which can be stimulated by DNA (see Campbell and Maxwell (2002), J.Biol.Chem. 320 p.171. The protein is expressed in E.coli.
Technical Documents
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酶对所作用的底物有严格的选择性。一种酶仅能作用于一种物质，或一类分子结构相似的物质，促其进行一定的化学反应，产生一定的反应产物，这种选择性作用称为酶的专一性。
DNA连接酶主要是连接DNA片段之间的磷酸二酯键最初从原核生物（大肠杆菌）分离得到的.现在生物基因工程主要是从T4噬菌体中分离得到的,
DNA连接酶:可以连接被限制酶切割开磷酸二酯键
大家有用过Invitrogen的T4连接酶吗？说明书上是23－26度连接，一般的连接酶不都是16度吗？应该用多少度呢？另外，说明书上还说连接后为了达到更好的转化效率，应将连接反应液至少稀释5倍再转化，是这样吗？谢谢大家帮忙啊
菌体构建时，目的基因连接在T载体上，测序也正确，但是将目的基因还有载体分别双酶切后总是连接不上，将连接后产物跑核酸胶，什么也没有，不知道是什么原因？我的目的基因浓度为9ng/ul,载体回收后的浓度为6ng/ul,是因为浓度太低的原因吗？还有就是连接有目的基因的T载体双酶切后出现了三条带，这个又是什么原因呢？希望得到解答
