Construction of a chiral artificial enzyme used for enantioselective catalysis in live cells

Nanozymes as a newcomer of artificial enzyme family, have shown several advantages over natural enzymes such as their high stability in harsh environments, facile production on large scale, long storage time, low costs, and more resistant to biodegradation. However, compared with natural enzymes, it is still a great challenge to design a nanozyme with high selectivity, especially high enantioselectivity. It is highly desirable and demanding to develop chiral nanozymes with high and on-demand enantioselectivity for practical applications. Herein, we present an unprecedented approach to construct chiral artificial peroxidase with ultrahigh enantioseletivity. Inspired by the structure of natural enzyme horse radish peroxidase (HRP), we have constructed a series of stereoselective nanozymes (Fe3O4@Poly(AA)) by using the ferromagnetic nanoparticle (Fe3O4 NP) yolk as the active site and amino acid-appended chiral polymer shell as the chiral selector. Among them, Fe3O4@Poly(D-Trp) possesses the highest enantioselectivity. More intriguingly, their enantioselectivity will be readily reversed by replacing D-Trp with L-Trp. The selectivity factor is up to 5.38, even higher than that of HRP. Kinetic parameters, dialysis experiments, molecular simulations together with activation energy reveal that the selectivity is originated from the D-/L-Trp appended polymer shell, which can result in better affinity and catalytic activity to D-/L-tyrosinol. The artificial peroxidases have been used for asymmetric catalysis to prepare enantiopure D- or L-enantiomer. Besides, by using fluorescent labelled FITC-L-tyrosinol and RhB-D-tyrosinol, the artificial peroxidase can catalyze green or red fluorescent chiral tyrosinol to selectively label live yeast cells among yeast, S.aureus, E.coli and B.subtilis bacteria cells. This work opens a new avenue for better design of stereoselective artificial enzymes.