Proteins Separation and Purification by Expanded Bed Adsorption and Simulated Moving Bed Technology

Proteins not only play an important role in biology, but also have large potential applications in pharmaceuticals and therapeutics, food processing, textiles and leather goods, detergents, and paper manufacturing. With the development of molecular biology technologies, various kinds of proteins can be prepared from upstream processes and from biological raw materials. However, there exist various proteins and contaminants in these source feedstocks, and the key issue is that proteins can be separated and purified efficiently from the source materials, in order to reduce the production cost of the high-purity protein. The development of techniques and methods for proteins separation and purification has been an essential prerequisite for many of the advancements made in biotechnology. Most separation and purification protocols require more than one step to achieve the desired level of protein purity. Usually, a three-step separation and purification strategy is presented, which includes capture, intermediate separation and purification, and final polishing during a downstream protein separation and purification process. In the capture step the objectives are to isolate, concentrate, and stabilize the target proteins. During the intermediate separation and purification step the objectives are to remove most of the bulk impurities, such as other proteins and nucleic acids, endotoxins, and viruses. In the polishing step most impurities have already been removed except for trace amounts or closely related substances. The objective is to achieve final purity of protein. In the capture step, as the primary recovery of proteins, the expanded bed adsorption (EBA) technology has been widely applied to capture proteins directly from crude unclarified source materials, such as, Escherichia coli homogenate, yeast, fermentation, mammalian cell culture, milk, and animal tissue extracts [1,2]. The expanded bed is designed in a way that the suspended adsorbent particles capture target protein molecules, while cells, cell debris, 1