1、在经过滤或离心后的样品中加入沉析剂; 2、沉淀物的陈化,促进晶体生长 3、离心或过滤,收集沉淀物 六、盐析( Salt induced precipitation 1、概念∶在高浓度的中性盐存在下,蛋白质(酶)等生物大分子物质在水溶液 中的溶解度降低,产生沉淀的过程 The most common type of precipitation for proteins is Salt induced precipitation Protein solubility depends on several factors. It is observed that at low concentration of the salt, solubility of the proteins usually increases slightly. This is termed Salting in. But at high concentrations of salt, the solubility of the proteins drops sharply. This is termed Salting out and the proteins precipitate out Solubility versus Salt Concentration 2、盐析原玨 首先需要了 (1)两性 散系 Salt concentration (2)蛋白质周围形成水化膜,保护了蛋白质粒子,避免了相互碰撞1、在经过滤或离心后的样品中加入沉析剂； 2、沉淀物的陈化，促进晶体生长； 3、离心或过滤，收集沉淀物； 六、盐析(Salt induced precipitation) 1、概念：在高浓度的中性盐存在下，蛋白质（酶）等生物大分子物质在水溶液 中的溶解度降低，产生沉淀的过程。 The most common type of precipitation for proteins is Salt induced precipitation. Protein solubility depends on several factors. It is observed that at low concentration of the salt, solubility of the proteins usually increases slightly. This is termed Salting in. But at high concentrations of salt, the solubility of the proteins drops sharply. This is termed Salting out and the proteins precipitate out. 2、盐析原理 首先需要了解生物大分子在水溶液中的存在状态： （1）两性电解质，由于静电力的作用，分子间相互排斥，形成稳定的分散系 （2）蛋白质周围形成水化膜，保护了蛋白质粒子，避免了相互碰撞