ABSTRACT
The production and recovery of recombinant proteins, although common, is by no means simple, and requires skills from many disciplines including molecular biology, biochemistry, genetics, and engineering. Since Watson and Crick’s discovery of DNA (1), a lot of research has focused on the upstream side of recombinant protein production, and numerous well-established vectors are available along with documented procedures to create the desired expression system. Protein production involves manipulating the cells to generate the desired protein, but just getting the cells to produce the amino acid sequence of interest does not guarantee a usable protein. The protein may not fold correctly, it may not have its activity, or it may be degraded either within the cell, in the culture medium, or during the recovery operations. The culture medium where the product is produced, and hence from where the product must be removed, can be a very complex mixture of polysaccharides, salts, proteins, amino acids, lipids, proteases, nucleic acids, steroids, vitamins, growth factors, whole cells, prions (if animal-derived supplements are used), and adventitious agents. Proteins are recovered from complex mixtures, and often the recovery and purification of that protein may not be economically feasible. It has been estimated that the expense attributed to the purification of a recombinant product can approach 60% (2) to 80% (3) of the total production cost. The successful production of a biological product must involve teamwork between the upstream and downstream engineers, since every component added to boost protein production must eventually be removed.
