(366f) Nanoparticle-Supported Multi-Enzyme Biocatalysis

Glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH) and coenzyme NAD+ were attached onto silica nanoparticles examined for biosynthesis of α-ketoglutarate from L-glutamate. The immobilized multi-enzyme catalyst retained about 50% of the activity of the free-enzyme system for the coupled reactions. Since nanoparticles always tend to agglomerate in the absence of dispersing agents such as surfactants, it was found that liquid-solid ratio of the reaction system had a great effect on the activity of the catalyst system. Overall, the particle-attached NAD⁺ showed effective interaction with the enzymes immobilized in the same way and achieved a TTN of around 20000 within one hour of reaction, corresponding to a glutamate conversion of 22.7%. Magnetic nanosilica particles were also examined for the immobilization of the catalyst system for easy catalyst recovery and reuse.