ABSTRACT

Use of recombinant proteins as human therapeutics has increased over the past several years. These proteins are often obtained from fermentation of microorganisms, such as E. coli. Following initial release of the crude product from the host cell by homogenization, the resulting solution contains species such as other bacterial host cell proteins (HCPs), nucleic acids (DNA and RNA), endotoxin, and other host cell impurities [1,2]. The challenge often in process development is to design a process that can purify the protein of interest from these impurities, to be consistent with current Good Manufacturing Practices (cGMP), and to ensure product safety [3,4]. Unless DNA and HCPs are cleared during processing and reduced to acceptable levels (typically ng/mg for HCPs and pg/mg for DNA), the product is unlikely to be used for clinical or commercial purposes [1,5]. These issues, combined with the presence of other product-related impurities that have very similar physicochemical properties to the product, make purification of the target molecule a challenge.