There is an insatiable demand for new protein-purification platforms. A notable contribution to this gaggle of approaches is based on the use of elastin-like biopolymers, as described by Ariel Boutaud, Ph.D., director of research at Phase Bioscience.
Much of the protein-purification technology within the biotech industry is based on the use of affinity chromatography, in which an expressed recombinant protein is fused to a peptide having high affinity for a particular ligand. A resin column is constructed with the ligand coupled to it, and the crude protein soup is passed through the column, leaving the target protein bound to the column. Subsequently the peptide tail can be removed, leaving the protein target.
While this approach is ubiquitous throughout the industry, it has notable shortcomings, including high cost and the need for specialized equipment and expensive resins. Scale-up to industrial levels is a hit-or-miss proposition, frequently frustrating and expensive, and yields can be paltry with significant loss.
The deltaPhase recombinant expression/purification system is based on the transition properties of elastin-like polymers and their ability to retain this inverse temperature-phase transition when conjugated to other molecules. The phase transition offers a new method of purification for therapeutic proteins and peptides. The process consists of fusing an ELP sequence to the N or C terminus of the polypeptide of interest by recombinant DNA techniques. The DNA coding for the polypeptide or protein tagged with an ELP is introduced into an expression system (e.g., E. coli or mammalian cells) for production.
Once the protein ELP fusion is produced, the cells are lysed in the case of an E. coli expression system or the culture supernatant is collected for a mammalian-expression platform. The ELP fusion protein is then phase transitioned to form insoluble aggregates, which are isolated by centrifugation or filtration. After isolating the aggregated ELP protein, it is resolubilized by decreasing the temperature. The ELP may then be cleaved enzymatically from the fusion protein. Another cycle of phase transition purification will separate any uncleaved product from the ELP, which remains in the insoluble fraction and leaves behind the purified product in the soluble fraction.
“We believe that the deltaPhase technology offers an innovative method for protein/polypeptide purification and avoids costly chromatography,” Dr. Boutaud stated. “We would argue that PhaseBio’s deltaPhase technology is the first new production and purification method developed in the last 20 years.”