中文摘要：

利用基因重组技术合成了具有良好细胞粘附活性的重组家蚕丝素-RGD融合蛋白质（Silk-RGD），探讨了其盐析的工艺条件。研究发现，在融合蛋白等电点pH8附近，当硫酸铵在溶液中的饱和度较低（10％）时，其蛋白质沉淀量随着温度的升高而增加；当硫酸铵的饱和度升至20％时，蛋白质沉淀量不再随着温度的变化而变化，但与低饱和度硫酸铵时相比，沉淀量明显增加；当硫酸铵的饱和度升至30％或以上时，沉淀中杂蛋白含量明显增多，不利于目的蛋白的纯化。Silk—RGD融合蛋白相对合理而且易操作的盐析纯化条件为：pH8，硫酸铵在溶液中的饱和度为20％，室温（约20℃）。利用该工艺条件，可以低成本、高效率地生产Silk—RGD融合蛋白，从而满足新型材料规模化开发的需要。

英文摘要：

By applying of genetic engineering strategies a Bombyx mori silk fibroin-RGD fusion protein （Silk-RGD） was synthesize, which showed a high cell adhesive ability, and the technological conditions for saltingout purification of the Silk-RGD were studied. The results revealed that the yield of salting-out precipitate increased with rise of temperature at the low （NH4）2SO4 concentration （10%） under pH 8 of isoelectric point; when the （NH4）2SO4 concentration increased to 20%, the yield was not temperature-dependent but much more than that at concentration of 10% ; when the （ NH4）2SO4 concentration increased to 30% or above, there were many impurities in the precipitates causing difficulties for purification of the target protein. As a conclusion, it seemed that the rational and easy operating salting-out conditions for purification of Silk-RGD were 20% of（NH4）2SO4 at room temperature （around 20 ℃） and pH 8. Under these conditions, Silk-RGD can be produced with high efficiency and low cost to meet the demands of development of new material in large scale.