Development of a Large-Scale Crystallization Step for the Purification of a Recombinant Therapeutic Protein

The development of a large scale batch crystallization unit operation is described for the purification of a recombinant therapeutic protein from an impure starting solution. To create an effective and scalable crystallization step, it is necessary to understand the parameters that affect the crystallization kinetics and crystal morphology. This was accomplished by investigating the solubility and crystal nucleation boundaries of the protein in various solutions and over a range of temperatures. In order to increase step yield, polyethylene glycol 3350 was used as an anti-solvent to decrease the solubility of the protein and maximize crystallization. Crystal recovery, washing and dissolution methods were also developed at small scale and subsequently transferred to a pilot plant facility.