| Nanotechnology is the study and use of materials with nanometer length scales. This unique size range presents a challenge for the production of well-defined assemblies. It is too big to create from standard chemistry techniques and too small for top-down engineering methods. We take the approach of using natural nanomaterials to create complex assemblies for a wide range of potential applications.;Here we report progress with a protein nanoparticle derived from the Qβ bacteriophage coat protein. This protein cage naturally binds RNA and we exploit this to package and confine functional proteins within the interior of the shell. In an effort to determine the capabilities of this RNA-packaging technology, we packaged an array of different cargo-enzymes within the protein nanoparticle. Further, we explored different variables that influence the packaging mechanism of some of these proteins to give the researcher some control over how many are loaded into each particle. These studies have also identified features of the technology that were not previously appreciated. The enzymes inside the nanoparticle are functional and comparisons with free enzymes highlight important effects that packaging has on each particular proteins. In general, the nanoparticle protects the packaged enzymes from inactivation due to non-specific proteases, adsorption, and long-term storage.;In order to use this technology to deliver therapeutic enzymes to a site of action, I combined the enzyme-packaging and ligand-display techniques, developed in the lab previously. This produced nanoparticles that could be used as potential therapeutics, but the non-specific binding of the protein nanoparticle slowed progress in vitro..;Finally, we manipulated the coat protein gene sequence to create self-assembling nanoparticles with different properties. Approximately half of these manipulations resulted in the loss of the ability of the coat protein to self-assemble, and the remainder had varying degrees of impact on the nanoparticle. One residue proved to be very important to the assembly mechanism and certain changes prompted the mutant coat protein to self-assemble into small aberrant structures. These were structurally investigated and may prove to be very helpful for the production of future functional materials. |
