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Integrated IgG Fragmentation and Fragment Purification Using a Reactant Adsorptive Membrane Bioreactor Separator System

Deqiang Yu and Raja Ghosh. Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4L8, Canada

Immunoglobulin G fragments are widely used for different diagnostic and therapeutic applications. Fragmentation of immunoglobulin G is useful for characterizing antibodies. The enzymatic fragmentation of IgG is traditionally carried out by homogeneous liquid phase reaction and followed multi-step purification to remove the enzyme and byproducts. These processes tend to be complex with low overall productivity. The current work deals with use of a membrane chromatography system as a bioreactor and separator. In conventional bioreactors, the biocatalyst is immobilized within the reactor and the reactant is passed through it for carrying out the enzymatic reaction. In our bioreactor system the reactant i.e. IgG is reversibly immobilized and the enzyme is allowed to flow through the system. This approach allows the reaction to be carried out and multiple components i.e. reactant, impurities, enzyme, product and byproduct to be separated using a single device. In the present work hydrophobic interaction membrane chromatography (HIMC) was utilized to obtain F(ab')2 and Fab fragments directly from human serum using enzymes pepsin and papain. The reactant adsorptive HIMC system was able to selectively adsorb IgG from serum. When the bound IgG was pulsed with the enzyme under optimized condition, different fragments were obtained and these could be fractionated based on their different interactions with the membrane adsorber. The main advantage of our approach is the great process simplification by efficient integration of IgG purification, reaction and separation. Other advantages include high conversion, low process time and scalability.