| Expression, Purification and Crystallization of Recombinant Arabidopsis Monogalactosyldiacylglycerol Synthase (MGD1)
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Author:
Date:
2016-12-20
[Abstract] In plant cells, galactolipids are predominant, representing up to 50% of the lipid content in photosynthetic tissues. Galactolipid synthesis is initiated by MGDG synthases (MGDs), which use UDP-galactose as a donor sugar and diacylglycerol (DAG) as acceptor, to form monogalactosyldiacylglycerol (MGDG). This protocol is used to produce a recombinant form of Arabidopsis thaliana (A. thaliana) monogalactosyldiacylglycerol synthase 1 (MGD1) protein, in Escherichia coli (E. coli), using a two-step chromatographic purification procedure. The protein is easily expressed and purified to milligram quantities, suitable for biochemical and structural studies. The crystallization of MGD1 is also described.
[摘要] 在植物细胞中，半乳糖脂是主要的，代表高达光合组织脂质含量的50％。通过使用UDP-半乳糖作为供体糖和二酰基甘油（DAG）作为受体的MGDG合成酶（MGD）启动半乳糖脂合成以形成单糖基二酰基甘油（MGDG）。该方案用于在大肠杆菌中产生拟南芥（Arabidopsis thaliana）（拟南芥）单糖半乳糖二酰基甘油合酶1（MGD1）蛋白的重组形式（大肠杆菌），使用两步色谱纯化方法。蛋白质容易表达和纯化至数量，适用于生物化学和结构研究。还描述了MGD1的结晶。
背景 以前在e中表达植物MGD的尝试。大肠杆菌显示约99％的重组蛋白质积累在包涵体中（Miège等，1999）。开发了使用洗涤剂或体外包涵体折叠方案的细菌膜的溶解，并产生足够的纯和活性级分，足以监测酶的活性，但不进行其结构研究（Nishiyama et ...
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| Extraction and Assays of ADP-glucose Pyrophosphorylase, Soluble Starch Synthase and Granule Bound Starch Synthase from Wheat (Triticum aestivum L.) Grains
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Author:
Date:
2016-09-20
[Abstract] Starch biosynthesis in plants involves a network of enzymes of which adenosine-5’-diphosphoglucose (ADP-glucose) pyrophosphorylase (AGPase, E.C. 2.7.7.27), and soluble and granule bound starch synthases (SSS and GBSS, E.C. 2.4.1.21) play central roles. Here, we outline the protocol for extraction and assay of these enzymes in developing grains of wheat (Triticum aestivum L.). The principle of the assays outlined is based on a coupling enzymatic reactions where the product of the initial reaction is used as a substrate for subsequent reactions in order to generate NADPH, which can be measured easily by spectrophotometer. This protocol does not need expensive labelled chemicals and can be carried out using equipment commonly found in a biochemical laboratory. We applied this ...
[摘要] 植物中的淀粉生物合成涉及酶的网络，其中腺苷-5'-二磷酸葡萄糖（ADP-葡萄糖）焦磷酸化酶（AGPase，EC 2.7.7.27）和可溶性和颗粒结合的淀粉合酶（SSS和GBSS，EC 2.4.1.21）中心角色。在这里，我们概述了用于提取和测定这些酶在开发小麦谷粒（ Triticum aestivum L）中的方案。概述的测定法的原理基于偶联酶反应，其中初始反应的产物用作随后反应的底物，以便产生NADPH，其可以通过分光光度计容易地测量。该方案不需要昂贵的标记的化学品，并且可以使用通常在生化实验室中发现的设备进行。我们应用这个协议来研究开花后不同时间点小麦籽粒中AGPase，SSS和GBSS活性的动力学。
[背景] 淀粉是一种碳水化合物聚合物由α-1,4-连接的葡萄糖分子组成的线性葡聚糖聚合物和支链淀粉（由α-1,6-糖苷键支化的α-1,4-连接的葡萄糖分子组成的另一种葡聚糖聚合物）。腺苷-5'-二磷酸葡萄糖（ADP-葡萄糖）焦磷酸化酶（AGPase，E.C.2.7.7.27）催化淀粉合成的第一承诺步骤，将葡萄糖-1-磷酸和ATP转化为ADP-葡萄糖和无机焦磷酸（PPi）。 ADP-葡萄糖随后被可溶性淀粉合成酶（SSS）和颗粒结合的淀粉合酶（GBSS）（EC 2.4.1.21）和淀粉分支酶使用以延长和分支淀粉颗粒的葡聚糖链。 ...
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| RAB21 Activity Assay Using GST-fused APPL1
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Author:
Date:
2016-02-20
[Abstract] The Rab family of small GTPases are essential regulators of membrane trafficking events. As with other small GTPase families, Rab GTPases cycle between an inactive GDP- bound state and an active GTP-bound state. Guanine nucleotide exchange factors (GEFs) promote Rab activation with the exchange of bound GDP for GTP, while GTPase-activating proteins (GAPs) regulate Rab inactivation with GTP hydrolysis. Numerous methods have been established to monitor the activation status of Rab GTPases. Of those, FRET-based methods are used to identify when and where a Rab GTPase is activated in cells. Unfortunately, the generation of such probes is complex, and only a limited number of Rabs have been probed this way. Biochemical purification of activated Rabs from cell or tissue extracts is easily ...
[摘要] 小GTP酶的Rab家族是膜运输事件的必要调节剂。与其他小GTP酶家族一样，Rab GTP酶在不活动的GDP结合状态和活性GTP结合状态之间循环。鸟嘌呤核苷酸交换因子（GEF）促进Rab激活与交换绑定GDP GTP，而GTPase激活蛋白（GAP）调节Rab失活与GTP水解。已经建立了许多方法来监测Rab GTPases的活化状态。其中，基于FRET的方法用于鉴定细胞中Rab GTPase在何时和何地被激活。不幸的是，这种探针的产生是复杂的，并且只有有限数量的Rab已经以这种方式探测。来自细胞或组织提取物的活化的Rabs的生物化学纯化通过使用已知的Rab效应结构域以下拉特定的GTP结合的Rab形式是容易实现的。虽然这种方法不是理想的详细的亚细胞定位，它可以提供Rab活动的时间分辨率。越来越多的特异性效应物的鉴定现在允许在特定条件下测试许多Rab GTP酶的活化水平。在这里，我们描述了一种亲和纯化方法使用GST融合APPL1（一种已知的RAB21效应）来测试哺乳动物细胞中的RAB21激活。该方法成功地用于测定RAB21激活状态下营养丰富与饥饿条件下的变化，并测试在此过程中MTMR13 RAB21 GEF的需求。
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