(313b) Coacervation of Sequence Controlled Polypeptides: Understanding Biology and Designing Materials

Electrostatic interactions have been implicated in a wide range of biological materials, including between proteins, polysaccharides, and polynucleotides. In particular, associations involving intrinsically disordered proteins have been implicated in the formation of an increasing number of liquid phase separated granules, or ‘membraneless organelles’ in cells. These intrinsically disordered proteins tend to include significant quantities of charged residues, and recent mutagenesis studies on biological materials have highlighted the importance of charge patterning in the assembly of these materials. We have utilized sequence-controlled polypeptides as a model system to study how the patterning or presentation of charges functionalities can modulate the potential for liquid-liquid phase separation via complex coacervation. Complex coacervation occurs as a result of electrostatic and entropic interactions between oppositely-charged polyelectrolytes. Our experimental results, supported by theory and simulation demonstrate the important role that chemical sequence plays in controlling the localization of condensed counterions and the structuring of water. Additionally, we have examined the role that charge patterning on the surface of globular proteins has on the tendency of such molecules to partition into coacervate phases. Our goal is to establish molecular-level design rules to facilitate the tailored creation of materials based on polyelectrolyte complexation that can both illuminate self-assembly phenomena found in nature, and find utility across a wide range of real-world applications.