Alpha-thrombin is a highly specific serine protease generated by proteolytic activation of the zymogen prothrombin (1). During coagulation, thrombin cleaves fibrinogen to form fibrin, leading to the ultimate step in coagulation, the formation of a fibrin clot. Thrombin is also responsible for feedback activation of the procofactors factor V and factor VIII. Thrombin has also been reported to activate factor XIII and platelets, and also functions as a vasoconstrictor protein. The procoagulant activity of thrombin is arrested in two ways: 1) inhibition by either heparin cofactor II or the antithrombin III/heparin complex; or 2) complex formation with thrombomodulin. Formation of the thrombin/thrombomodulin complex results in the inability of thrombin to cleave fibrinogen and activate factors V and VIII, but increases the efficiency of thrombin for activation of the anticoagulant, protein C.
Thrombin is a two chain enzyme composed of an NH2-terminal "A" chain (Mr=6,000) and a COOH-terminal "B" chain (Mr=31,000) which remain covalently associated through a single disulfide bond. Human thrombin is 13 amino acids shorter than the bovine thrombin due to a thrombin cleavage site on the human protein that is not present in the bovine protein.
Thrombin is also utilized for site specific cleavage of fusion proteins expressed in bacteria (9-11). A thrombin 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 thrombin. Thrombin can then be easily removed by affinity chromatography.
Human, bovine and mouse thrombin are prepared from purified prothrombin using a modification of the Lundblad procedure (1) as described by Nesheim et al. (2). Thrombin is supplied in 50% (vol/vol) glycerol/H2O and should be stored at -20oC. Purity is determined by SDS-PAGE analysis and activity is measured in a thrombin specific clotting assay, and compared to standardized NIH thrombin. Thrombin is also available with the active site blocked with either DFP, FPRck, or biotinlyated FPRck.
Cleavage of Fusion ProteinsIn addition to its broad application in coagulation research thrombin can be used for site specific cleavage of fusion proteins. A thrombin 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 thrombin. Thrombin can then be easily removed by affinity chromatography. Lot to lot consistency ensures reproducible results every time. For experiments involving cell cultures, please contact us to discuss custom, low endotoxin lots designated for cell culture use.
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我的邮箱：maoyuanqing@citiz.net
**捷向您推荐美国Trevigen的一款通用PARP分析试剂盒检测试剂盒。该试剂盒是检测凋亡前与凋亡中细胞提取液中PARP活性的理想方案，操作简单，重复性高。其通过检测96孔板上生物素标记的多聚ADP核糖聚合到邻近组蛋白的反应，从而确定已知的或可能的PARP抑制剂。试剂盒中的依托泊苷（Etoposide）是拓扑异构酶Ⅱ抑制剂，在拓扑异构酶Ⅱ切割完DNA后能够稳定该酶。在试剂盒中，依托泊苷作为凋亡诱导的对照参与检测。
通量PARP/凋亡分析试剂盒可广泛应用于1）检测原代、肿瘤等细胞的PARP活性；2）检测凋亡前后的PARP活性；3）利用细胞裂解液筛选PARP抑制剂。
试剂盒特色比色法/化学发光法，无放射性输出。96well，高通量检测。极大地节省了分析时间，提高了使用效率。高敏感性。能够检测到500个细胞中低至0.1mU的PARP。检测范围广。0.1-10mU。样本用量少。仅仅需要10-100ng的提取物。检测时间短。仅需要3h即可完成检测。
**捷向您提供一站式的PARP相关实验解决方案，除了高通量PARP/凋亡分析试剂盒，还有PARP体内药理动力学二代分析试剂盒(PDAII)和通用PAPR分析试剂盒外(含组蛋白包被可拆卸板)，以及相关抗体和重组蛋白。
Trevigen是一家快速成长的美国生物技术公司，专注于细胞凋亡、DNA损伤和修复、肿瘤细胞功能与行为等方面研究的肿瘤研究产品和服务。作为Trevigen在中国区域的总代理，**捷与Trevigen一道为中国的科研工作者提供最好、最新的氧化应激、细胞损伤和肿瘤细胞行为研究等领域内的优质产品和技术服务。如果您对上述产品及方案感兴趣，请致电400-6800-868至**捷科技有限公司垂询血管生成研究的相关实验解决方案，或索取最新的产品资料。
A.优点：
多重分析——一次分析可以检测16种干细胞相关的TF
定量比较——二个样本的差异可以定量分析和比较
步骤简单——探针温育、柱分离、板杂交和HRP检测
无需贵重仪器——无需如Luminex那样的贵重仪器
B.原理：
干细胞转录因子活性多重检测阵列试剂用于同时检测多种TF活性。该技术中，基于TFDNA结合位点的一致性序列，制备一系列生物素标记的探针。当探针混合物与核提取物一起温育时，每个探针寻找相应的TF，形成TF/探针复合物，通过柱离心纯化可以很容易与游离探针分开。结合的探针从混合物中分离出来，通过板杂交分析。板孔中预包被上与探针互补的特异序列，捕获的DNA探针进一步用链酶亲和素-HRP检测，化学发光检测仪测定发光强度（RLUs）。
