ELP-z and ELP-zz capturing scaffolds for the purification of immunoglobulins by affinity precipitation

The increasing demand of monoclonal antibodies for therapeutic applications along with the high manufacturing cost have made it necessary to evaluate better process options and technologies for their purification. Affinity precipitation is an attractive alternative to traditional chromatographic methods by affording effective purification using a simple environmental trigger. The feature of elastin-like-protein (ELP) fused with antibody binding domains has already been explored for the purification of antibodies. However, ELP when fused with the bulkier domains such as Protein A, resulted in lower protein production. In this study, ELP was fused to smaller synthetic IgG binding domains such as the z or zz domain, resulting in up to 10-fold higher level of production. Both ELP-z and ELP-zz bind tightly to human immunoglobulin (HIgG) with a dissociation constant of 768±142 nM and 68±23 nM, respectively. Owing to the higher binding affinity, the use of ELP-zz resulted in more than 99% recovery of HIgG in four repeated binding and elution cycles with no observable decrease in the purification performance. The same binding and elution cycle was successfully implemented for the purification of monoclonal antibodies from hybridoma culture supernatant with close to 100% recovery.