Enzymatic nanoreactors for environmentally benign biotransformations. 1. Formation and catalytic activity of supramolecular complexes of laccase and linear-dendritic block copolymers

We describe the construction of enzymatic nanoreactors through noncovalent envelopment of a glycoprotein by amphiphilic linear-dendritic AB or ABA copolymers. The synthetic procedure is based on the regioselective adsorption of dendritic poly(benzyl ether)-block-linear poly(ethylene glycol)-block-dendritic poly(benzyl ether) or linear poly(ethylene oxide)-block-dendritic poly(benzyl ether) copolymers onto the oxidative enzyme laccase from Trametes versicolor in aqueous medium. The complexes formed have improved catalytic activity compared with the native enzyme (77-85 nkat/mL vs 60 nkat/mL, respectively) and are more stable at elevated temperatures up to 70 °C. Experiments with deglycosylated laccase confirm that the glycoside fragments in the native enzyme serve as the anchor sites for the linear-dendritic copolymers. The enzymatic nanoreactors are able to effectively oxidize series of substrates: phenolic compounds (syringaldazine) and hydrophobic polyaromatic hydrocarbons (anthracene and benzo[a]pyrene) under "green" chemistry conditions.