Protein Crystallization in Stirred-Tank Reactors

Dirk Hebel, doctoral thesis Technische Universität München, 2013

Increasing product concentrations are achieved in biotechnological production processes for proteins. Hence, the subsequent isolation and purification of proteins using state of the art technologies becomes more and more economically challenging. Protein crystallization could contribute to a simplification of the downstream processing. In this work, suitable crystallization conditions for five different proteins were characterized in microbatch experiments. Parallel operated stirred-tank reactors on a milliliter scale were applied to increase the yield of the protein crystallization processes to up to 99 % within 2 hours by temperature shifts, the addition of crystallization agents, or the addition of novel additives, i.e., ionic liquids. The scale-up based on geometrically similar stirred-tanks up to the liter-scale was successful. Additionally, the crystallization agents could be depleted from the crystals by diffusion.

Publications

• Hebel D, Huber S, Stanislawski B, Hekmat D (2013): Stirred batch crystallization of a therapeutic antibody fragment. J Biotechnol 166: 206-211.
• Hebel D, Ürdingen M, Hekmat D, Weuster-Botz D (2013): Development and scale-up of high-yield crystallization processes of lysozyme and lipase using additives. Cryst Growth Des 13: 2499-2506.
• Hekmat D, Hebel D, Weuster-Botz D (2008): Crystalline proteins as an alternative to standard formulations. Chem Eng Technol 31: 911-916.
• Hekmat D, Hebel D, Schmid H, Weuster-Botz D (2007): Crystallization of lysozyme: from vapor diffusion experiments to batch crystallization in agitated ml-scale vessels. Proc Biochem 42: 1649-1654.
• Hekmat D, Hebel D, Joswig S, Schmidt M, Weuster-Botz D (2007): Advanced protein crystallization using water-soluble ionic liquids as crystallization additives. Biotechnol Lett 29: 1703-1711.