Synthesis of Polymerizable Protein Monomers for Protein-Acrylamide Hydrogel Formation

A novel method to produce protein polymer conjugates for protein-acrylamide hydrogel formation is described. Alkenes are incorporated onto the N-terminus of expressed proteins to produce polymerizable protein monomers that can be utilized in protein-acrylamide copolymerization. A 4-vinylbenzoic acid thioester was synthesized and attached to the N-termini of two protein models, the immunoglobulin-binding protein Protein G and the bacterial enzyme xanthine-guanine phosphoribosyl transferase (GPRT), utilizing native chemical ligation. N-terminal cysteine containing proteins utilized in native chemical ligation reactions were generated from His-tagged fusion proteins using tobacco etch virus NIa (TEV) protease cleavage. The 4-vinylbenzyl functionalized proteins were good substrates for immobilizing proteins into polyacrylamide hydrogels via free radical induced protein-acrylamide copolymerization. The protein copolymerization procedures developed in this report are mild enough to allow proteins to retain measurable biological activity as demonstrated by the retention of immunoglobulin binding ability by immobilized Protein G and enzymatic activity of immobilized GPRT.