Covalent and non-covalent strategies for the immobilization of Tobacco Etch Virus protease (TEVp) on superparamagnetic nanoparticles.

Proteases with highly specific activities have numerous applications, including the cleavage of affinity tags (Flag; HA; His6X) and solubility promoting partners (GST; MBP) within the context of protein isolation and purification schemes. However, commercially sourced proteases such as Tobacco Etch Virus protease (TEVp) and Human Rhinovirus (HRV) 3C protease are typically applied as single use aliquots, which limits their cost-effectiveness. In addition, the presence of residual proteases in downstream applications can complicate analysis of the protein of interest. Thus, the creation of immobilized, reusable site-specific proteases would be of significant value to the life science community. In this work, we explore two strategies for the immobilization of TEV protease onto superparamagnetic iron oxide nanoparticles (SPIONs). In one strategy, a MBP-TEVp-Streptavidin fusion protein is immobilized on biotin-functionalized SPIONs. In a second strategy, TEV protease is covalently coupled onto SPIONs directly, via amine-mediated attachment, and indirectly, via HALO-tag mediated attachment. We demonstrate activity of our immobilized proteases in the presence of a MBP-GFP fusion protein containing the TEV protease target sequence (ENLYFQ|S). We then analyze time-dependent activity, longevity, and reuse of these immobilized protein preparations, comparing each approach. The protease immobilization strategies described in this work may be useful tools for simplifying challenging protein purification protocols, in addition to providing general methods for enzyme immobilization on SPIONs.