【2017年整理】DNA的溶解度问题.docVIP

乙醇沉淀法是一种常用的技术集中的盐在水溶液中的核酸（DNA或RNA）准备。 The basic procedure is that salt and ethanol are added to the aqueous solution, which forces the nucleic acid to precipitate out of solution.其基本做法是，加入盐和乙醇水溶液，这迫使核酸沉淀出的解决方案。 The precipitated nucleic acid can then be separated from the rest of the solution by centrifugation.然后可以休息的解决方案，通过离心分离沉淀核酸。 The pellet is washed in cold 70% ethanol then after a further centrifugation step the ethanol is removed, and the nucleic acid pellet is allowed to dry before being resuspended in clean aqueous buffer.在寒冷的70％乙醇洗涤沉淀，然后再经过离心步骤乙醇被删除，并允许核酸颗粒干燥，然后在干净的缓冲溶液中悬浮。 So how does this work?那么如何工作的呢？ A bit about solubility… 关于溶解度的位... First we need to know why nucleic acids are soluble in water.首先，我们需要知道为什么核酸是易溶于水。 Water is a polar molecule – it has a partial negative charge near the oxygen atom due the unshared pairs of electrons, and partial positive charges near the hydrogen atoms (see the diagram on the right).水是极性分子 - 它有一个部分负电荷的氧原子附近，由于共用电子对，部分正电荷的氢原子（见右图）附近。 Because of these charges, polar molecules, like DNA or RNA, can interact electrostatically with the water molecules, allowing them to easily dissolve in water.极性分子，如DNA或RNA，因为这些费用，可以与水分子的静电相互作用，使他们能够很容易溶解于水。 Polar molecules can therefore be described as hydrophilic and non-polar molecules, which cant easily interact with water molecules, are hydrophobic.极性分子，因此可以被描述为亲水性和非极性分子，不能轻易与水分子相互作用，疏水。 Nucleic acids are hydrophilic due to the negatively charged phosphate (PO3-) groups along the sugar phosphate backbone.核酸是亲水性由于带负电荷的磷（PO3-）组沿糖磷酸骨架。 The role of the salt… 盐的作用... Ok, so back to the protocol.好吧，这样的协议。 The role of the salt in the protocol is to neutralize the charges on the sugar phosphate backbone.盐在协议中的作用是消除糖磷酸骨架上的收费。 A commonly used salt is sodium acetate.一种常用的盐是醋酸钠。 In solution, sodium acetate breaks up into Na+ and [CH3COO]-.在溶液中，分解成Na +和[醋酸 - 醋酸钠。 The positively charged sodium ions neutralize the negative charge on the PO3- groups on the nucleic acids, making the molecule far l