ELP-ZZ Fusions for the Purification of Immunoglobulins by Affinity Precipitation

           The increase in demand of monoclonal antibodies for therapeutic applications along with the high manufacturing cost has made it necessary to evaluate better process options and technologies. Downstream purification of antibodies, which typically accounts for 50-80% of the total manufacturing cost, is a prime cost-cutting target. Affinity precipitation is an attractive alternative to traditional chromatographic methods by affording effective purification using a simple environmental trigger.  In the current study, a Fc-binding zz domain fused to the C-terminus of an elastin like protein [ELP] was used as a new capture scaffold. The tunable hydrophobic interaction exhibited by the stimuli-responsive ELP was exploited as a non-covalent method to reversibly capture antibodies based on interaction with the zz domain.  Up to 96% IgG capturing was achieved in a single precipitation step, while over 95% of the captured IgG was recovered after elution. The ELP-zz capture scaffold can be reused three times without any loss of binding efficiency. More importantly, one-step purification was also demonstrated for secreted IgG directly from hybridoma supernatant. Utility of this new technology for industrial IgG purification will be discussed as well.