Incorporating non-natural amino acids that contain reactive groups within assembling sequences can provide a handle for covalent modification or crosslinking of assembled structures. However, how the incorporation of such amino acids will affect the hydrogen bonding and other intermolecular interactions and multiscale properties of these systems is difficult to assess or predict. New approaches are needed to better understand the impact of amino acid substitutions and incorporation on the secondary and tertiary structures of assembling peptides toward improved design rules.<br/><br/>We have created multifunctional collagen mimetic peptides (mfCMPs) that self-assemble into triple helices and fibrils and contain reactive handles for covalent crosslinking and reinforcement toward mimicking the structure and mechanical properties of collagen-rich microenvironments. A non-native amino acid in the form of an allyloxycarbonyl (alloc)-protected lysine residue was incorporated at different positions within the mfCMPs toward their covalent modification. The addition of this alloc-protected lysine influenced the ability of these peptides to form triple helices in solution, evidenced by lowered melting temperatures in peptides with the alloc-protecting group (~10<sup>o</sup>C) in comparison to their ‘wild type’ variants. To probe this, atomistic simulations were performed on peptides with single and double amino acid mutations. These atomistic (AA) molecular dynamics (MD) simulations demonstrate how these CMP sequence mutations impact the local stability, around the mutation(s), within the triple helix. The experimental measurements correlated well with the AA simulations and demonstrate the impact of alloc incorporation and placement on assembly. However, since AA MD simulations are computationally intensive and incapable of capturing triple helix melting or helices assembly into fibers, we have complemented them with coarse-grained (CG) simulations. The CG MD simulations predict the melting of single triple helix and assembly/disassembly of the helices as a function of sequence changes. Taken together, our experimental and simulation approaches provide insight into the design of assembling peptides with non-natural substitutions to facilitate the formation and modification of fibrous nanostructured materials systems for a variety of applications.

Understanding the impact of non-natural amino acid incorporation on the assembly of multifunctional collagen mimetic peptides

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.