Preparation and application of lacto-N-biose synthases immobilized onto amino-modified SiO2 nanoparticles

Following modification with APTES, the -NH 2 density reached to 12.04 groups/nm 2 . • Immobilized enzymes showed enhanced stability and broadened optimal reaction range. • Immobilization of LNB synthase by SNPs-NH₂ exhibited positive catalytic modulation. • After 7 cycles, the activity retention rate of the immobilized enzymes was 74–85%. • During 7 cycles of LNB synthesis, the LNB yield was maintained above 90%. Lacto-N-biose (LNB) is the core structural unit of human milk oligosaccharides and plays an indispensable role in the growth and development of infants. In this study, amino-modified SiO 2 nanoparticles (SNPs-NH 2 ) were used as carriers to immobilize sucrose phosphorylase (SPase), UDP-galactose-4′-epimerase (GalE), galactose-1-phosphate uridylyltransferase (GalT), and lacto-N-biose phosphorylase (LNBP), and LNB was synthesized in a one-pot method with high efficiency. The results showed that after activation of SNPs for 16 h at 25 °C with 2 mol/L hydrochloric acid, and modification with 3-Aminopropyltrimethoxysilane (APTES)/SNPs (2:1, v /m) at 65 °C for 9 h, the interface -NH 2 grafting density reached to 12.04 groups/nm 2 . Under the optimal immobilization conditions, the SPase, GalE, GalT, and LNBP were all well-loaded onto the carriers. At the same time, the temperature and pH stability of the enzymes were significantly improved, and the optimal reaction range was significantly expanded. The enzyme activity retention rate after 7 cycles of reaction was 74% to 85%, with the LNB synthesis yield rate remaining above 90%. This study effectively simplified the separation of enzymes from the reaction system during LNB synthesis and improved its stability, laying a foundation for the industrial production of LNB. Download: Download high-res image (107KB) Download: Download full-size image