E. coli Topoisomerase IV
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E. coli Topoisomerase IV
Topo IV (from Escherichia coli) is prepared by overexpressing the parC and parE subunits in E. coli and purifying them by methods adapted from Peng and Marians, 19991.
The parC and parE subunits are purified to >95% purity as judged by SDS-PAGE. The topo IV is supplied as a heterotetramer complex in Dilution buffer.
It is recommended that the enzyme is aliquoted to avoid repeated freeze-thaw cycles. Store at -80ºC.
All enzyme is supplied with 5X concentrated Assay Buffer and Dilution buffers which are also available separately.
See technical documents below for more detailed information and lot specific activities.
Technical Documents
E. coli Topoisomerase IV Relaxation Assay Kits
These contain the enzyme and the supercoiled DNA substrate in addition to the Assay and Dilution buffers for relaxation reactions. 1 U of topo IV will relax 0.5 µg supercoiled pBR322 DNA in 30 minutes at 37°C.
Technical Documents
E. coli Topoisomerase IV DecatenationAssay Kits
These contain the enzyme and the catenated kDNA substrate in addition to the Assay and Dilution buffers for decatenation reactions. 1 U of topo IV 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.
Technical Documents
E. coli Topoisomerase IV Assay Kits for Cell Extracts
These kits are designed for assaying cell extracts and partially purified fractions containing over-expressed topo IV and contain supercoiled DNA substrate, Assay buffer, Dilution buffer, control relaxed DNA and stop buffer/loading dye.
Technical Documents
E. coli Topoisomerase IV Cleavage Assay Kits
These kits are designed specifically for cleavage reactions. They contain topo IV enzyme, supercoiled pBR322 DNA substrate and the Assay and Dilution buffers required for DNA cleavage reactions in addition to the enzyme and linearised pBR322 marker.
Cleavage specific enzyme available separately on request.
Technical Documents
E.coli Topoisomerase IV ATPase kits
These kits can be used to test the effects of potential ATPase inhibitors. For example, the coumarin drugs such as novobiocin inhibit the action of topoisomerase IV by competitively inhibiting the hydrolysis of ATP thus preventing supercoiling.
These assays are microtitre plate-based and thus large numbers of compounds can be screened in a relatively short period of time. They also continuous assays which can provide more information than an end point assay.
Technical Documents
High / Medium-Throughput Assay Kit - E. coli Topoisomerase IV
The kit is supplied with sufficient E. coli topo IV 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.
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
References
- Peng, H. and Marians, K.J. (1999) Overexpression and purification of bacterial topoisomerase IV, in DNA Topoisomerase Protocols Vol. I (Bjornsti, M-A., and Osheroff, N. eds.), Humana Press, Totowa, N.Jersey pp.163-169
- Maxwell, A., Burton, N.P. and O"Hagan, N. (2006) High-throughput assays for DNA gyrase and other topoisomerases. Nucleic Acid Res. 34 (15), e104
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我在做5RACE,选用TaKaRa公司的RNA反转录酶(RNaseH-),不知道这个酶好不好,有什么需要注意的。
没有序列识别的功能,他就是简单的催化相邻DNA链的5-P末端和3'-OH末端以磷酸二酯键结合的反应,需ATP作辅酶。 不仅可以催化粘性末端之间或平滑末端之间的DNA的连接,也催化DNA与RNA之间以及少数RNA之间的连接。
反转录酶(Reversetranscripatase)是以RNA为模板指导三磷酸脱氧核苷酸合成互补DNA(cDNA)的酶。哺乳类C型病毒的反转录酶和鼠类B型病毒的反转录酶都是一条多肽链。鸟类RNA病毒的反转录酶则由两上亚基结构。真核生物中也都分离出具有不同结构的反转录酶。

