A modulatory bifunctional artificial enzyme with both SOD and GPx activities based on a smart star-shaped pseudo-block copolymer

An artificial smart bifunctional enzyme with both superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities was successfully constructed by the self-assembly of a porphyrin core with four suspensory adamantyl moieties and β-cyclodextrin-terminated temperature-sensitive copolymer through host-guest interaction in aqueous solution. The Mn(iii) porphyrin, Mn(iii)meso-tetra[1-(1-adamantyl methyl ketone)-4-pyridyl] porphyrin (MnTPyP-M-Ad), was designed as both a "supramolecular linker" and an efficient active site of SOD and the temperature-responsive block copolymer (β-CD-PEG-b-PNIPAAm-Te) with incorporated tellurium moieties in the PNIPAAm chain as GPx active sites was synthesized by ATRP. As a new type of artificial bifunctional enzymes, it exhibited stable SOD-like activity of 0.137 μM (IC₅₀) at 37 °C, and high GPx catalytic efficiency with temperature-responsive dependence characteristic, and the new artificial enzyme was found to exhibit the highest GPx catalytic efficiency (v₀ = 8.11 μM min^-1) in close to physical temperature.