Researcher(s)
- Sabrina Liskey, Chemical Engineering, University of Virginia
Faculty Mentor(s)
- Darrin Pochan, Materials Science and Engineering, University of Delaware
Abstract
Gaining precise control over protein hierarchical structures is contingent upon understanding and improving the predictability of self-assembled nanostructures. This research investigates the self assembly of coiled-coil bundlemers, a structural motif commonly found in natural proteins such as keratin, cytokines, and viral fusion proteins. Oppositely charged bundlemers have been previously shown to assemble into lattice nanostructures, which are desirable for their uniform surface properties. The sequences used in this study were designed with different charged states compared to previously studied bundlemers to investigate the effect of charged residues on lattice formation. This work serves as a comparison between four distinct co-assemblies: mixed-charge neg-5 and neg-6 bundlemers, both at pH 7 and 10 (all assemblies used the same single-charge pos-6 bundlemer). Each assembly was examined using transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). TEM and SAXS data showed that the neg-5 assemblies formed larger and more orderly structures compared to both neg-6 assemblies. Therefore, because the only difference between the two 29-residue sequences is the presence of glutamine or glutamic acid at the 27th residue, it can be concluded that having glutamine in the 27th position is more favorable for organized lattice formation. The SAXS data, which gives a more detailed view of the internal geometry of the lattices, showed that the neg-6 assemblies demonstrated a more orderly structure at pH 7. Although previous sequences of the same charge have shown structural changes due to varying pH, the two neg-5 assemblies did not exhibit any internal structural differences between pH 7 and 10.