Efficient downstream processes, role

Role of Statistically Designed Experiments in the Development of Efficient Downstream Processes... 

Formation of IBs during protein expression poses a bottleneck in the efficient downstream processing of therapeutic proteins. The reasons for IB formation are not fully known. Because translation is a slower process than protein folding, it is likely that the misfolding of translation intermediates plays some role. Further, since post-translational modifications, such as glycosylation and lyposylation, which are known to affect the secondary structure of proteins, are absent in bacteria, the non-modified protein structure may cause misfolding. The recovery of soluble... 

The fermentation process and downstream processing are usually unlinked. The fermentation broth is harvested and stored, and the recovery is carried out later. In rare cases, when the product is not stable, purification is carried out immediately after fermentation. The construct of the expression plasmid also influences the purification strategy. It is important to take this fact into account when an efficient and sustainable process must be designed. The expression plasmid determines whether a protein is secreted into the culture medium, into the periplasm, or stays in the cytoplasm. It also plays a pivotal role in the half-life of a protein. Although it may sound odd, the N-terminal amino acid is responsible for the half-life of a protein in the cell [26,27]. The most important features determining the functionality of an expression system are listed in Table 2. The expression system, together with the mode of operation, produces a characteristic product concentration profile with time (Fig. 3). 

---