Activation of the zymogen, factor X, by either the intrinsic or extrinsic factor Xase complexes produces the active serine protease factor Xa (1,2). The activation of factor X requires proteolytic cleavage of the heavy chain, resulting in the release of an activation glycopeptide. The heavy chain region in factor Xa contains the serine protease catalytic domain, while the light chain, as in the zymogen, contains the membrane binding domain.
Factor Xa (molecular weight 46,000) participates in the prothrombinase complex, which catalyzes the rapid conversion of prothrombin to thrombin. Prothrombinase is an enzyme complex composed of factor Xa (enzyme) and factor Va (cofactor) assembled on a cellular surface in the presence of calcium ions. Although factor Xa can independently catalyze the activation of prothrombin, the rate at which this reaction occurs is increased nearly 300,000-fold with complete assembly of the prothrombinase complex. The clotting activity of factor Xa in vivo is terminated by either inactivation of the cofactor, factor Va, or by direct inhibition of factor Xa by inhibitors, such as ATIII, after disassembly of the prothrombinase complex.
In addition to its broad application in coagulation research, factor Xa can be utilized for site specific cleavage of fusion proteins expressed in bacteria (9-12). A factor Xa-sensitive site is incorporated between the recombinant protein of interest and peptides or proteins which facilitate purification and/or expression. The target protein is released from the expressed hybrid by cleavage with factor Xa. The factor Xa can then be easily removed by affinity chromatography.
Factor Xa is prepared by activating purified factor X with the factor X activator isolated from Russell"s viper venom. Factor Xa is purified from the activation mixture by chromatography over benzamidine-Sepharose followed by gel filtration (1,3). Several modified forms of factor Xa are also available including: A) active-site blocked factor Xa containing either the tripeptide chloromethyl ketone inhibitor EGRck, or the fluorescent inhibitor Dansyl-EGRck; and B) human Gla-domainless β-factor Xa. The enzyme is supplied in 50% (vol/vol) glycerol/H2O and should be stored at -20°C. Purity is determined by SDS-PAGE analysis and activity is measured in a factor Xa clotting assay and/or chromogenic substrate assay. Lot to lot consistency ensures reproducible results every time.
Cell culture: For experiments involving cell cultures, please contact us to discuss custom, low endotoxin lots designated for cell culture use.
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一抗的英语是 resistance No.1,二抗resistance No.2.
我的实验是这样的,先纯化质粒,然后做酶切,再纯化DNA。
最后一步其实也可以用切胶回收试剂盒,我怕做不好,所以想选用DNA纯化试剂盒,但不知跟质粒DNA提取试剂盒是否有区别,因为说明书上说可以用Invitrogen的K210001.我搜索看了一席啊,觉得那个是提取质粒的小提啊。所以产生这个疑问,请大侠告知DNA纯化试剂盒与质粒DNA提取试剂盒这两者之间有区别吗?
用哪个公司的DNA纯化试剂盒比较好。谢谢啦!
想通过亲和层析来纯化抗血小板特异性抗体(抗GPIIb/IIIa抗体和抗GPIbα抗体),能否做到呢?谢谢!
液体的一抗加50%甘油,-20度也不会冻结,可保存3-5年;
经常使用时取出一小份,4度可使用半年之久;
粉末状的二抗直接-20或-80度贮藏就行了。
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