Tremendous success in molecular biology and gene engineering has made it pos­ sible to express practically any given amino acid sequence and to synthesize practically any desired protein. That success has overshadowed the fact that to be used commercially the expressed protein should be purified to a sufficient degree depending on its final application. The higher the required purity of the protein is the more expensive purification procedure is, mounting to 80% of the overall production costs [1]. The efficiency and economic liability of the purifica­ tion process determine often the fate of the protein product on the market. Purifi­ cation of a protein from a fermentation broth generally involves a combination of techniques resolving the proteins according to their size, charge, hydrophobicity, or ability to bind some particular substances (affinity ligands, chelated metal ions, HS-containing substances). These techniques have traditionally been optimized individually rather than as a part of the integrated, continuous process. Moreover, a lot of the development and refining of the purification protocol has been carried out on a laboratory scale with little consideration given to the econ­ omy of scaling up.