D-Amino Acid Oxidase Immobilized on Pt Nanoparticle-Loaded Porous SiO2 Nanospheres Coated with a Zirconium-Based Coordination Polymer for Catalytic Deamination of D-Alanine

Porous SiO2 nanospheres are prepared and loaded with platinum (Pt) nanoparticles (Pt&SiO2). The Pt&SiO2 nanospheres are coated with a zirconium-based coordination polymer (Pt&SiO2&Zr-cp). Etching of the core SiO(2 )with NaOH produces hollow nanospheres Pt&h-SiO2&Zr-cp. D-Amino acid oxidase (DAAO) with hexahistidine tags was absorbed onto the hollow nanospheres strongly, by utilizing the coordinative interactions between Zr(IV) and the hexahistidine tags. The conjugate DAAO&Pt&h-SiO2&Zr-cp possesses two-enzyme catalysis capability. The adsorbed DAAO catalyzes oxidative deamination of D-amino acids, and hydrogen peroxide (H2O2) is evolved as a byproduct. The loaded Pt nanoparticles possess peroxidase activity, decomposing H2O2 into H2O and O-2. Thus, the byproduct inhibitory effect can be minimized. In addition, the generated dioxygen O(2 )can be used to oxidize the reduced cofactor FDA of the adsorbed DAAO. The hybrid DAAO&Pt&h-SiO2&Zr-cp was applied for catalytic deamination of D-alanine and exhibited a catalytic efficiency more than four times that of free DAAO.

Automated summary

Porous SiO2 nanospheres loaded with platinum nanoparticles are coated with a zirconium-based coordination polymer, then etched with NaOH to create hollow nanospheres with dual-enzyme catalysis capability. The hybrid composite, when applied to catalytic deamination of D-alanine, exhibits a catalytic efficiency more than four times that of free DAAO.