
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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磷酸肌酸激酶(CPK),主要存在于骨骼肌和心肌,在脑组织中也存在,是参与体内的能量代谢的一种酶。在临床上主要用于诊断心肌梗塞。心肌梗塞患者发病后2-4小时,血液中此酶活动即开始升高。比血清中谷草转酸酶和乳酸脱氢酶的活力变化都出现得早。
临床意义:
(1)心肌梗塞后,CPK较谷草转氨酶和乳酸脱氢酶特异性高,但持续时间短,2-4天恢复正常。
(2)病毒性心肌炎,CPK也可升高,对诊断及预后有参考价值。
(3)进行性肌营养不良、多发性肌炎以及肌肉损伤时CPK也可升高。
(4)严重的心绞痛、心包炎、房颤、脑血管意外、脑膜炎以及心脏手术等,CPK可见升高。
根据磷酸化的底物不同,可将蛋白激酶分为组蛋白蛋白激酶、酪蛋白蛋白激酶等,但由于蛋白激酶可磷酸化底物的多样化,这种分法很不确切,已经被根据底物磷酸化氨基酸的分类方法所取代,有些如酪蛋白蛋白激酶,只是由于习惯而一直被沿用下来。根据有无调节物将蛋白激酶分为信使依赖的蛋白激酶和非信使依赖的蛋白激酶,有些信使依赖的蛋白激酶的首字母缩略词已为人们所接受,如cAMP依赖的蛋白激酶PKA、钙和磷脂依赖的蛋白激酶PKC以及钙依赖钙调素不依赖的蛋白激酶CDPK等,它们彼此间存在结构和功能上的相关关系。
也有人认为:蛋白激酶在信号转导中主要作用有两个方面:其一是通过磷酸化调节蛋白质的活性,磷酸化和去磷酸化是绝大多数信号通路组分可逆激活的共同机制,有些蛋白质在磷酸化后具有活性,有些则在去磷酸化后具有活性;其二是通过蛋白质的逐级磷酸化,使信号逐级放大,引起细胞反应.
protease
水解蛋白质肽键的一类酶的总称。按其水解多肽的方式,可以将其分为内肽酶和外肽酶两类。内肽酶将蛋白质分子内部切断,形成分子量较小的月示和胨。外肽酶从蛋白质分子的游离氨基或羧基的末端逐个将肽键水解,而游离出氨基酸,前者为氨基肽酶后者为羧基肽酶。按其活性中心和最适pH值,又可将蛋白酶分为丝氨酸蛋白酶、巯基蛋白酶、金属蛋白酶和酸性蛋白酶。按其反应的最适pH值,分为酸性蛋白酶、中性蛋白酶和碱性蛋白酶。工业生产上应用的蛋白酶,主要是内肽酶。
蛋白激酶
protein kinase
又称蛋白质磷酸化酶(protein phosphakinase)。一类催化蛋白质磷酸化反应的酶。

