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Magnesium chloride hexahydrate

氯化镁六水合物

Company: Sigma-Aldrich
Catalog#: M2670
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Guanine Nucleotide Exchange Assay Using Fluorescent MANT-GDP
Author:
Date:
2018-04-05
[Abstract]  GTPases are molecular switches that cycle between the inactive GDP-bound state and the active GTP-bound state. GTPases exchange nucleotides either by its intrinsic nucleotide exchange or by interaction with guanine nucleotide exchange factors (GEFs). Monitoring the nucleotide exchange in vitro, together with reconstitution of direct interactions with regulatory proteins, provides key insights into how a GTPase is activated. In this protocol, we describe core methods to monitor nucleotide exchange using fluorescent N-Methylanthraniloyl (MANT)-guanine nucleotide. [摘要]  GTP酶是分子开关,在无效GDP结合状态和活性GTP结合状态之间循环。 GTP酶通过其内在的核苷酸交换或通过与鸟嘌呤核苷酸交换因子(GEF)的相互作用来交换核苷酸。 监测体外核苷酸交换,以及与调节蛋白直接相互作用的重构,为GTP酶如何被激活提供了重要见解。 在该协议中,我们描述了使用荧光N-甲基呋喃酰基(MANT) - 鸟嘌呤核苷酸来监测核苷酸交换的核心方法。

【背景】GTPase是鸟嘌呤核苷酸结合蛋白,调节细胞过程的广度,从蛋白质生物合成到细胞周期进展,从细胞骨架重组到膜运输。 GTPases可以被认为是分子开关,它在GDP结合“关闭”状态和GTP结合“开启”状态之间循环;在通过GTP的GDP核苷酸交换结合GTP时,GTP酶变得活跃并且将结合下游效应蛋白以招募和激活这些效应子的生物学功能。 GTP酶通过与开关I环(G2结构域)的高度保守苏氨酸和开关II环(G3结构域)的DxxG基序内的甘氨酸的相互作用结合GTP的γ-磷酸。 GTP水解后,与γ-磷酸相互作用的丧失导致动态构象变化,从而使GTPase变为关闭状态(Vetter and ...

Determining Ribosome Translational Status by Ribo-ELISA
Author:
Date:
2018-01-05
[Abstract]  The Ribo-ELISA was originally developed to elucidate the basis for the ribopuromycylation method (RPM)-based detection of ribosome bound nascent chains. The Ribo-ELISA enables characterization of the translational status of ribosomes, and can be applied to the discovery of super-ribosomal complexes with novel ribosome associated macromolecules that are isolated by physical fractionation in sucrose gradients or other methods. [摘要]  Ribo-ELISA最初是为阐明基于核糖核苷酸化方法(RPM)的核糖体结合新生链检测的基础而开发的。 Ribo-ELISA能够表征核糖体的翻译状态,并且可以应用于通过蔗糖梯度中的物理分离或其他方法分离的新型核糖体相关大分子的超核糖体复合物的发现。

【背景】核糖体是由40S和60S亚单位组成的异构结构,当多个核糖体与单个mRNA结合时,它们以单体和多核糖体存在于细胞中。 另外,翻译核糖体可以与调节翻译的多个分子复合物相关联。 核糖体ELISA(Enzyme-Linked ImmunoSorbent Assay)能够通过核糖体相关新生链的体外嘌呤化检测翻译核糖体(David等人,2012)。 在将嘌呤霉素添加至具有结合的新生链的核糖体时,这种化学反应自发进行。 该方法定量测定每个核糖体中出现的新生链的数量,并且可以用于确定单核细胞相对于多核糖体的翻译状态,并鉴定结合其他大分子的核糖体,其改变其在沉淀柱中的沉降速率或迁移。

Analysis of Direct Interaction between Viral DNA-binding Proteins by Protein Pull-down Co-immunoprecipitation Assay
Author:
Date:
2018-01-05
[Abstract]  This protocol analyzes the direct interaction between two DNA-binding proteins by pull-down co-immunoprecipitation. One of the proteins is overexpressed in E. coli as HA-tagged recombinant protein and cell-free extracts are immunoprecipitated in HA-affinity resin. Cell extracts are treated with nuclease to degrade DNA and RNA, which rules out nucleic acid-mediated indirect interaction. Then, a second immunoprecipitation step is performed using the purified putative partner protein. Co-immunoprecipitated proteins can be detected either by Coomassie Blue staining and/or Western blotting (WB) if a specific antibody is available. Moreover, many DNA/RNA binding proteins are highly electropositive, which can hinder WB under standard conditions, as has been shown in histones and ... [摘要]  该协议通过下拉共免疫沉淀分析两种DNA结合蛋白之间的直接相互作用。其中一种蛋白在E中过表达。如HA标记的重组蛋白和无细胞提取物在HA亲和树脂中免疫沉淀。用核酸酶处理细胞提取物以降解DNA和RNA,这排除了核酸介导的间接相互作用。然后,使用纯化的推定的配偶体蛋白进行第二次免疫沉淀步骤。如果特异性抗体可用,可以通过考马斯蓝染色和/或Western印迹(WB)检测免疫共沉淀蛋白质。此外,许多DNA / RNA结合蛋白具有高度正电性,在标准条件下可阻碍WB,正如组蛋白和组蛋白样蛋白所示。在这种情况下,我们表明,假定的合作伙伴的高等电点导致转移不良。提示麻烦WB提供高正电荷DNA结合蛋白的转移。


【背景】共免疫沉淀是分析蛋白质 - 蛋白质相互作用(PPI)的常用方法。许多共免疫沉淀方案使用细菌表达的蛋白质。然而,细胞提取物的使用不排除由第三种蛋白介导的间接相互作用,或者在DNA / RNA结合蛋白的情况下介导核酸。

乙型病毒Bam35(B35TP)的末端蛋白含有保守的酪氨酸194,其提供OH基团以在蛋白质引发的DNA复制期间锚定病毒基因组的第一个5'-dTMP。此外,B35TP具有很强的DNA结合能力,与许多DNA结合蛋白一样,它具有非常高的等电点(约10.6),这影响其体外稳定性和功能(Berjón-Otero 等),2016)。 ...

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