Nondestructive Regioselective Modification of Laccase by Linear-Dendritic Copolymers: Enhanced Oxidation of Benzo-α-Pyrene in Water

摘要

This chapter describes a novel approach towards enzyme modification which avoids generation or disruption of covalent chemical linkages or genetic intervention. A unique feature of this strategy is that a glycoenzyme, substrates and applicable cofactors are confined within the well-defined nanoporous regions of a regular micelle constructed by an amphiphilic linear-dendritic block copolymer containing water-soluble linear fragments and hydrophobic dendritic blocks. This new construction principle is illustrated with the enzyme laccase from Trametes versicolor. The complexes were shown to be capable of converting the essentially non-substrate veratryl alcohol to veratryl aldehyde. Further, the activity of this laccase complex in aqueous media, enhanced with selected hydrophobic N-hydroxy mediators, provided the expected diquinone products from the essentially insoluble model compound benzo-α-pyrene. Control probes with laccase, mediators and conventional linear-linear copolymers with comparable molecular weight characteristics failed to evince such substrate oxidation. These results presage application of glycoenzyme/linear-dendritic complexes for the biotransformation of variety of precursors, not normally enzyme substrates by virtue of their insolubility under physiological conditions, to usefurintermediates.