Concanavalin Α Enabled High Performance Enzyme Cascades on Magnetic Nanoparticles

Concanavalin A (ConA) is a lectin that specifically binds to carbohydrates containing non-reducing terminal α-D-mannosyl or α-D-glucosyl moieties. Here we present a facile and aqueous method preparing multiple glycolenzyme catalysts using ConA coated magnetic nanoparticles (ConA-MNP). The first step is to from a ConA layer on the surface of MNP (ConA-MNP) by crosslinking with glutaraldehyde. Then glycoenzymes were agglutinated on the surface of ConA-MNP spontaneously, followed by crosslinking with glutaraldehyde.

The resulted GOx-HRP@ConA-MNP showed an over 80% residual activity compared to their native counterparts in solution. In contrast, merely no activity was observed when the enzymes were directly immobilized on MNP via crosslinking with glutaraldehyde. The GOx-HRP@ConA-MNP retained over 90% of the initial activity after 10 cycles. Above mentioned procedure was applied to form GOx-Cat@ConA-MNP for catalyzing the conversion of glucose to gluconic acid. It was evidenced by both structural characterization and reaction kinetics that the co-localization of the cascade enzymes enabled a substrate looping between two enzymes, i.e., oxygen produced by Cat was confined to GOx producing H₂O₂ as a substrate for Cat. As a result GOx-Cat@ConA-MNP achieves 91% glucose conversion in 75 minutes whereas the aqueous GOx and Cat reached a conversion of 86%. The GOx-Cat@ConA-MNP retained 99% after 8 cycles with a glucose conversions over 90% in each run.

The high catalytic performance and the ease of operation makes the multiple enzymes @ConA-MNP appealing for enzyme cascades for various applications.