Synthesis and characterization of a new class of cationic protein polymers for multivalent display and biomaterial applications

Monodisperse protein polymers engineered by biosynthetic techniques are well suited to serve as a basis for creating comb-like polymer architectures for biomaterial applications. We have developed a new class of linear, cationic, random-coil protein polymers designed to act as scaffolds for multivalent display. These polymers contain evenly spaced lysine residues that allow for chemical or enzymatic conjugation of pendant functional groups. Circular dichroism (CD) spectroscopy and turbidity experiments have confirmed that these proteins have a random coil structure and are soluble up to at least 65 °C. Cell viability assays suggest these constructs are non-toxic in solution up to a concentration of 100 μM. We have successfully attached a small bioactive peptide, a peptoid-peptide hybrid, a poly(ethylene glycol) (PEG) polymer, and a fluorophore to the protein polymers by chemical or enzymatic coupling, demonstrating their suitability to serve as multivalent scaffolds in solutions or as gels.