Grafting through Method for Implanting of Lysozyme Enzyme in Molecular Brush for Improved Biocatalytic Activity and Thermal Stability

We report a “grafting through” conjugation strategy to improve lysozyme catalytic activity and thermal stability by the synthesis of a synthetic polymer–enzyme hybrid. The lysozyme was first conjugated with glycidyl methacrylate via ring-opening reaction between epoxy groups and lysine residues of the enzyme to synthesize the enzyme macromonomer. The conjugation was followed by free radical copolymerization of the macromonomer with poly(ethylene glycol) methyl ether acrylate (PEGMEA) (Mn = 5000 g/mol) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) (Mn = 500 g/mol). We demonstrated that implanting of a single lysozyme molecule in the molecular brush polymer chain resulted a significant improvement of the thermal stability up to 90 °C and 9-time extended half-life for this synthetic enzyme structure. The improved enzyme performance is explained by the crowding effect provided by molecular brush architecture of the synthetic hybrid.