
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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1.若都为正常,那么并未有太大问题,只要定期复查就可以了。
2.如果TGAb、TMAb、甲状腺功能均高,那么就是桥本氏甲状腺炎并甲亢,需要抗甲亢治疗。
3.如果TGAb、TMAb高,甲状腺功能下降,那么就是桥本氏甲状腺炎并甲减,需要进行甲减治疗。
4.如果TGAb、TMAb高,甲状腺功能正常,那么就是桥本氏甲状腺炎,无需特殊治疗,只要定期复查甲状腺功能就可能以了,不过这种情况有可能以后演变成甲减或者甲亢。
BAS-ELISA是在常规ELISA原理的基础上,结合生物素(B)与亲和素(A)间的高度放大作用,而建立的一种检测系统。生物素很易与蛋白质(如抗体等)以共价键结合。这样,结合了酶的亲和素分子与结合有特异性抗体的生物素分子产生反应,既起到了多级放大作用,又由于酶在遇到相应底物时的催化作用而呈色,达到检测未知抗原(或抗体)分子的目的。
1.若都为正常,那么并未有太大问题,只要定期复查就可以了。
2.如果TGAb、TMAb、甲状腺功能均高,那么就是桥本氏甲状腺炎并甲亢,需要抗甲亢治疗。
3.如果TGAb、TMAb高,甲状腺功能下降,那么就是桥本氏甲状腺炎并甲减,需要进行甲减治疗。
4.如果TGAb、TMAb高,甲状腺功能正常,那么就是桥本氏甲状腺炎,无需特殊治疗,只要定期复查甲状腺功能就可能以了,不过这种情况有可能以后演变成甲减或者甲亢。
试题分析:酶是一种生物催化剂,在催化反应中本身不发生变化;此非酶的特性;B项体现了酶的作用条件较温和的特性;C项体现了酶的专一性;D项体现了酶的高效性;故选A。
考点:本题考查的是酶的特性。
点评:对于此类试题,学生应掌握酶的特性。

