Modulation of protein activity and assembled structure by polymer conjugation: PEGylation vs glycosylation

PEGylation and glycosylation are utilized in this research as different bioconjugation tools to modify proteins, yielding conjugates with different enzyme activity and assembled structure. Active succinimidyl esters are first synthesized through a facile one-step reaction for the alkyne-functionalization of proteins. Well-defined polymers with controlled MW, narrow dispersity and terminal azide groups, including thermoresponsive poly(PEG) and glycopolymers, are then synthesized via a combination of copper mediated living radical polymerization (Cu(0)-LRP) following azidation reaction. Copper catalyzed azide and alkyne cycloaddition reaction (CuAAC) is finally performed to conjugate poly(PEG) or glycopolymers with the alkyne-functionalized laccase from Trametes versicolor . The coupling of polymers induces further self-assembly of laccase-polymer conjugates into spherical nanoparticles with well dispersion stability and stimuli-responsive behaviours in water. Enzyme activity of the conjugates are also studied, during which the glycosylated laccase has shown relatively higher activity than the PEGylated laccase.