Recombinant Human ACE2-Fc-Avi Protein (rhACE2-Fc)
Source: recombinant human ACE2 protein (Gln18-Ser740) was expressed in mammalian cells with a Fc fusion and Avi at the C-terminus.Accession: Q9BYF1Predicted molecular mass: 111.2 kDa. Due to glycosylation, the rhACE2 protein migrates to 115-125 kDa based on the Bis-Tris PAGE result.Endotoxin: Less than 0.5 EU per ug by the LAL method.Activity: Immobilized biotinylated recombinant SARS-CoV-2 Spike S RBD with the His Tag at 1 ug/ml (100 ul/well). Dose response curve for rhACE2-Fc fusion protein with the EC50 of 81 ng/ml determined by ELISA. Conditions of optimal recombinant Human ACE2 protein (rhACE2-Fc) performance should be determined experimentally by the investigator.Formulation: The recombinant human ACE2-Fc-Avi protein was lyophilized from 0.22 um filtered solution in 20 mM PB (pH 7.4). Normally 5% trehalose is added as protectant before lyophilization.Purity: > 95% by PAGE under reduced condition, and SEC-HPLC.Shipping: The recombinant human ACE2-Fc-Avi protein is shipped with ice packs. Upon receipt, store it immediately at the temperature recommended below.Stability & Storage:Use a manual defrost freezer and avoid repeated freeze-thaw cycles.12 months from date of receipt, -20 to -70°C as supplied.1 month, 2 to 8°C under sterile conditions after reconstitution.3 months, -20 to -70°C under sterile conditions after reconstitution.
Background
ACE2 (Angiotensin I Converting Enzyme 2) belongs to the angiotensin-converting enzyme family of dipeptidylcarboxydipeptidases and has considerable homology to human angiotensin 1 converting enzyme. This secreted protein catalyzes the cleavage of angiotensin I into angiotensin 1-9, and angiotensin II into the vasodilator angiotensin 1-7. Diseases associated with ACE2 include Severe Acute Respiratory Syndrome (SARS) including Coronavirus Disease 2019 (COVID-19), and Neurogenic Hypertension. The SARS-CoV and SARS-CoV-2 (2019-nCoV) spike (S) proteins mediate viral entry into host cells by binding to the ACE2 receptor through the receptor-binding domain (RBD) of the S1 subunit, and then fusing the viral and host membranes through the S2 subunit. The ACE2-binding affinity of the Spike RBD of SARS-CoV-2 is 10- to 20-fold higher than that of SARS-CoV. Two trimeric SARS-CoV-2 spike proteins bind to an ACE2 dimer with the collectrin-like domain of ACE2 mediating homodimerization.
The binding of the S1 subunit to the extracellular peptidase domain of ACE2 on the surface of cells results in endocytosis and translocation of both the virus and the enzyme into endosomes located within cells. This entry process also requires priming of the S protein by the host serine protease TMPRSS2, which is a potential drug for inhibition. The recombinant human ACE2 (rhACE2) may also be a promising drug for those with intolerance to classic renin-angiotensin system inhibitors (RAS inhibitors) or in diseases where circulating angiotensin II is elevated. Infused rhACE2 has been evaluated in clinical trials for the treatment of SARS.
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1.两种方法哪一种更加准确？
2.那一种方法更方便？
3.需要的仪器上海哪家单位有？
描述物质分子对辐射吸收的程度随波长而变的函数关系曲线，称为吸收光谱或吸收曲线。紫外-可见吸收光谱通常由一个或几个宽吸收谱带组成。最大吸收波长（λmax）表示物质对辐射的特征吸收或选择吸收，它与分子中外层电子或价电子的结构（或成键、非键和反键电子）有关。朗伯-比尔定律是分光光度法和比色法的基础。这个定律表示：当一束具有I0强度的单色辐射照射到吸收层厚度为b，浓度为c的吸光物质时，辐射能的吸收依赖于该物质的浓度与吸收层的厚度。其数学表达式为： 式中的A叫做吸光度；I0为入射辐射强度；I为透过吸收层的辐射强度；（I／I0）称紫藤为透射率T；ε是一个常数，叫做摩尔吸光系数，ε值愈大，分光光度法测定的灵敏度愈高。
紫外-可见分光光度计由5个部件组成：①辐射源。必须具有稳定的、有足够输出功率的、能提供仪器使用波段的连续光谱，如钨灯、卤钨灯（波长范围350～2500纳米），氘灯或氢灯（180～460纳米），或可调谐染料激光光源等。②单色器[1]。它由入射、出射狭缝、透镜系统和色散元件（棱镜或光栅）组成，是用以产生高纯度单色光束的装置，其功能包括将光源产生的复合光分解为单色光和分出所需的单色光束。③试样容器，又称吸收池。供盛放试液进行吸光度测量之用，分为石英池和玻璃池两种，前者适用于紫外到可见区，后者只适用于可见区。容器的光程一般为0.5～10厘米。④检测器，又称光电转换器。常用的有光电管或光电倍增管，后者较前者更灵敏，特别适用于检测较弱的辐射。近年来还使用光导摄像管或光电二极管矩阵作检测器，具有快速扫描的特点。⑤显示装置。这部分装置发展较快。较高级的光度计，常备有微处理机、荧光屏显示和记录仪等，可将图谱、数据和操作条件都显示出来。
仪器类型则有：单波长单光束直读式分光光度计，单波长双光束自动记录式分光光度计和双波长双光束分光光度计。
应用范围包括：①定量分析，广泛用于各种物料中微量、超微量和常量的无机和有机物质的测定。②定性和结构分析，紫外吸收光谱还可用于推断空间阻碍效应、氢键的强度、互变异构、几何异构现象等。③反应动力学研究，即研究反应物浓度随时间而变化的函数关系，测定反应速度和反应级数，探讨反应机理。④研究溶液平衡，如测定络合物的组成，稳定常数、酸碱离解常数等。
荧光分析法 利用某些物质被紫外光照射后所发生的能反映出该物质特性的荧光，
可以进行定性或定量分析的方法。
特点：灵敏度更高 10-10-10-12g/ml，应用不如UV广泛。
应用：①直接荧光光度法
②作为HPLC的检测器（用的多）展开
市面上的一些荧光剂，为了使之能够长久发光，部分不法分子会加入一些放射性物质，放射性物质的射线被荧光物质吸收从而发光，放射性物质显然是容易致癌的，某些放射性物质进入身体还有可能会变成内放射源。
但无论如何，荧光物质种类众多，不能一概而论。
但是因为荧光剂是一种会溶于液体并随之迁移又很难去除的化学物质，所以一旦洗衣液中的荧光剂附着在衣物上，用洗衣机大力清洗，也不用担心被洗掉，对人的皮肤和身体都有害，所以选择不含荧光剂的衣衣不舍洗衣宝是必要的。
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