Peptides that are short sequences of amino acids are excellent candidates for biomaterial construction as they provide a diverse and tunable interaction landscape at the nanoscale while also being relatively straightforward to synthesize and modify using lab-scale chemical procedures. Computational prediction of peptide sequences has enabled faster screening of sequences that facilitates deterministic biomaterial design. We demonstrate the utility of such computationally designed peptide assemblies as model colloidal systems for studying protein-protein interactions. Specifically, the assembly of artificial peptides that are predicted in silico to form α- helical coiled coils also known as bundlemers will be discussed. The peptides tetramerize to form a robust anisotropic nanoparticle with a stable hydrophobic core and multiple surface exposed polar and charged side groups. These groups can be strategically placed or chemically modified to display different net charges and patterns on the bundlemer surface. Via a constant feedback cycle between experimental results and computational sequence prediction, we have tested multiple design rules for successful bundlemer construction displaying different net charges (+32e to -32e). Specifically, we have confirmed that the bundlemers are robust nanocylinders and are consistently ≈ 4 nm in length and ≈ 2 nm in diameter, making them ideal colloidal nanoparticles that can also mimic the complex protein surface. In-depth small angle scattering investigation shows that while bundlemers behave as repulsive colloidal particles that are sensitive to net bundlemer charge and consequently, on solution conditions such as peptide concentration, pH and ionic strength, their solution behavior is further impacted by the subtle sequence-driven charge patterns on their surface. This sequence-specific solution behavior of bundlemers puts them at the cross-section of polyampholyte, polyelectrolyte and colloids research, the sum of which is important for describing protein-protein interactions in a holistic manner. Important parallels between these systems in context of the computational design and resulting sequence-driven solution behavior of the model bundlemers will be discussed.

Computationally designed coiled coil peptides as model charge-patterned colloidal particles

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

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