Assemblies of two multimeric enzymes using mesoporous silica microspheres toward cascade reaction fields

Abstract

A highly efficient, rapid cascade reaction system with coupled enzyme reactions is developed using mesoporous silica microspheres having a large pore diameter of 24.5 nm as an immobilization scaffold for two multimeric enzymes. The simultaneous adsorption of glucose oxidase and catalase on the pores of the mesoporous silica microspheres cause aggregation of the two enzymes, resulting in extremely low adsorbed amounts of the enzymes. The present study overcomes this limitation by immobilizing the two enzymes sequentially on the mesoporous silica pores, which significantly increases the decomposition ratio of hydrogen peroxide (an intermediate product). The localization and assembly of the two enzymes encapsulated in the mesopores were confirmed by labeling with fluorescent dyes for direct visualization and by detection of the fluorescence resonance energy transfer between the two enzymes, respectively, under a confocal laser scanning microscope field. The activity in the cascade reaction by the dual enzyme–mesoporous silica composite was significantly improved via the dense arrangement of the two enzymes on the surface of the mesoporous silica microspheres.