Protein purification is divided into many aspects of the problem, because proteins will have different structures and classifications, as well as the application of the industry you want to have a variety of different separation and purification methods, we recommend that the owner choose a book on protein purification to learn.
Biology better website I think:
Small woodworm /index.html
China Chromatography Network / is also worth referring to, because chromatography technology in the separation of proteins is a very practical method.