S. aureus Gyrase
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S. aureus Gyrase
Staphylococcus aureus gyrase is a bacterial type II topoisomerase which can introduce negative supercoils into DNA. It is a target for both quinolone and coumarin drugs and can be used for screening potential antibacterial compounds. It is prepared by overexpressing the subunits in E. coli and then purified.
It is supplied as an A2B2 complex in Dilution Buffer. Store at -80 °C.
All enzyme is supplied with 5X concentrated Assay Buffer and Dilution Buffer which are also available separately. 1 U of gyrase will supercoil 0.5 µg relaxed pBR322 DNA in 30 minutes at 37 °C.
See technical documents below for more detailed information and lot specific activities.
Technical Documents
S. aureus Gyrase Supercoiling Assay Kits
Kits are available containing everything required to perform supercoiling reactions and to test inhibitors. They contain the enzyme, relaxed DNA substrate and the Assay and Dilution buffers.
Technical Documents
S. aureus Gyrase Cleavage Assay Kits
Some drugs interrupt the DNA breakage-reunion step of the gyrase reaction. This leads to cell death and it is the mechanism behind the action of the quinolones such as nalidixic acid and ciprofloxacin. Cleavage assays are particularly useful in determining if a potential drug acts by this mechanism.
These kits are designed specifically for cleavage reactions. They contain the supercoiled pBR322 DNA substrate and the Assay and Dilution buffers required for DNA cleavage reactions in addition to the S. aureus gyrase and linearised pBR322 marker.
Cleavage specific enzyme available separately on request.
Technical Documents
S. aureus Gyrase Assay Kits for Cell Extracts
These kits are designed for assaying cell extracts containing gyrase and partially purified fractions and contain relaxed DNA substrate, Assay buffer, Dilution buffer and control supercoiled DNA.
Technical Documents
S. aureus Gyrase ATPase Kits
The coumarin drugs inhibit the action of gyrase by competitively inhibiting the hydrolysis of ATP thus preventing supercoiling. These kits can be used to test the effects of potential ATPase inhibitors.
These kits are advantageous because the assays are microtitre plate-based and thus large numbers of compounds can be screened in a relatively short period of time.
Technical Documents
High / Medium-Throughput Assay Kit - S. aureus Gyrase
The kit is supplied with sufficient S. aureus gyrase 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
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2、取灭过菌且无核酸酶的0.2ml离心管,依次加入2~5μgRNAnμL
3、65℃保温5min,然后冰浴5min;
4、往3步骤中的0.2ml离心管依次加入下列组份
RNase抑制剂(40u/μL)0.5μL
10×M-MLVReactionBuffer2μL
DTT(200mM)1μL
逆转录酶(M-MLV)1μL
5、轻轻混匀后,然后2000rpm离心20s;
6、先在37℃保温1hr,然后70℃保温15min;
7、上述产物可立即进行下一步的PCR反应或-20℃保存。向左转|向右转
各位大侠:小弟最近做个长片段的CDNA与T载体的连接,片段大小6.4K,载体选用的是pUC19和pGEMT-easy,反转录酶用的是RevertAidTirstStrandcDNASynthesisKit(#K1621),CDNA第二链的扩增用的是LATaq。我是用纯病毒的RNA做模板,操作步骤严格按照说明做的,也曾经有一次获得过电泳图清晰显示的是全长6.4KB左右的片段,与载体连接,结果筛选到的几个克隆,插入的片段仅有2KB左右,奈何?可最近几次再用此反转录试剂盒却不能得到所需片段。在此,小弟想问问大家,你们是否遇到同样的问题,是如何解决的?所用的试剂(载体和酶的选择)和方法是什么,可以告诉后来者,共同进步吧。
2. 禽成髓细胞瘤病毒(AMV)反转录酶:有强的聚合酶活性和RNA酶H活性。最适作用温度为42℃。
3.Thermus thermophilus、Thermus flavus等嗜热微生物的热稳定性反转录酶:在Mn存在下,允许高温反转录RNA,以消除RNA模板的二级结构。
4.MMLV反转录酶的RNase H突变体:商品名为SuperScript 和SuperScriptⅡ。此种酶较其它酶能多将更大部分的RNA转换成cDNA,这一特性允许从含二级结构的、低温反转录很困难的mRNA模板合成较长cDNA。向左转|向右转
在进行RT反应之前,应考虑以下几个方面:
1、RNA
成功的cDNA合成来自高质量的RNA,高质量的RNA至少应保证全长并且不含逆转录酶的抑制剂,如EDTA或SDS。在提取RNA的过程中,要特别防止RNase的污染,同时在逆转录反应中经常加入RNase抑制剂以增加cDNA合成的长度和产量。RNase抑制剂要在第一链cDNA合成反应中,在缓冲液和还原剂(如DTT)存在的条件下加入,因为cDNA合成前的过程会使抑制剂变性,从而释放结合的可以降解RNA的RNase。蛋白RNase抑制剂仅防止RNaseA,B,C对RNA的降解,并不能防止皮肤上的RNase,因此尽管使用了这些抑制剂,也要小心不要从手指上引入RNase,实验过程中经常更换新手套。
2、引物的选择
OligodT
选择OligodT时,要求RNA必须有PolyA,所以真核生物的mRNA都适用。适合长链甚至全长mRNA的RT,所以对RNA样品的质量要求较高,最好不要有明显的DNA污染、RNA降解和RNA断裂。假如想探索新的mRNA进行RT反应,建议推荐使用OligodT引物。使用OligodT引物要比随机引物和特异性引物的稳定性要好。
随机引物
适合各种RNA的RT,尤其适合模板丰度很低的情况(比如某个gene表达量很低)。选择随机引物时,第一链cDNA合成反应中就是以所有的RNA为模板,然后进行PCR反应时设计引物进行特异性扩增。同时要注意随机引物的量和总RNA量之间的关系,一般建议每5μg总RNA的随机引物的用量为50ng,如果每5μg总RNA的随机引物的用量超过250ng,可能会导致小片段产物(<500bp)的增加和长片断、全长产物产物的降低。
特异性引物
特异性引物只能用你设计引物时的下游引物做RT,引物设计质量影响RT的结果,而且不同引物退火温度本来就不相同,所以按照说明书按照一个温度做不是最佳选择,一般不推荐。向左转|向右转
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