Although affinity tag methods for protein purification have greatly accelerated research in laboratories throughout the world, the presence of the tag on the purified target can modify the target and has prevented these methods from being used for clinical applications. To address these limitations, we have spent over 20 years developing a truly practical self-cleaving tag technology. In practice, once the tagged target is bound to its cognate affinity resin and washed, the tag is induced to release the tagless target from the bound tag by a small shift in pH. This method thus allows the elution of a native target from an affinity resin, without the need for exogenous protease addition or the requirement for a downstream tag removal step. We have now been able to demonstrate this system for proteins expressed in E. coli and mammalian cells, where we have been able to purify “tagless and traceless” targets that include enzymes, antigens, complex glycoproteins and potential biosimilar therapeutics. In designing this system, we have focused carefully on aspects that will make it more attractive to the biopharmaceutical industry. The result is a resin that is compatible with conventional buffers and chromatography systems, has a competitive price point at large scale, and can be reused for multiple manufacturing cycles. It is our hope that this technology will provide a bridge between the research and manufacturing worlds of protein purification, where a single platform can now be used from the earliest high-throughput discovery efforts through full-scale clinical production.
1. Understand the basic design of this self-cleaving tag technology
2. Evaluate the performance of the technology in different contexts using case studies
3. Clarify the limitations and caveats to the technology for proposed applications