ABSTRACT
Many of the therapeutic and diagnostic products of the biotechnological industry are natural or recombinant proteins. These may be produced in a variety of systems such as bacterial, yeast, or mammalian cell cultures, and for most applications are required in final formulations of high purity. Techniques for the recovery of proteins have different requirements than those of traditional chemical processing. This is in part due to the sensitivity of the native protein structure and function to factors such as temperature, pressure, proteases, and interfacial contact (Kaufmann 1997). The other important difference in the separation of chemically produced compounds is the medium from which the material has to be isolated. Protein sources usually contain particulate material, together with a wide variety of compounds such as other proteins, lipids, and nucleic acids, each in a relatively low concentration, the desired protein being a minor component in the mixture.
