Study On Coimmobilizaton Of Glucose Oxidase And Horseradish Peroxidase For Catalyzing Asymmetric Synthesis Of Sulfoxide

Both glucose oxidase (GOX) and horseradish Peroxidase (HRP) are commercially available enzymes widely used in many different fields. The former is usually produced from Aspergillus niger, while the later is extracted from a kind of plant, horseradish. In this thesis, co-immobilization of these two enzymes was studied and the immobilized enzyme was characterized and applied to catalyze oxidation of thioanisole to chiral sulfoxidation.(1) Co-immobilization. Macroporous cation exchange resin D380 and polyurethane (PUR) foam were chose as the immobilization carrier, The HRP and GOX were covalently coimmobilized on them. The optimal activities and activity yields were 56 U·g-1(carrier) and 13% respectively for D380-GOX-HRP, while they were 313 U·g-1(carrier) and 44% for PUR-GOX-HRP.(2) Characteristic of co-immobilized enzymes. The optimum pH of D380-GOX-HRP and PUR-GOX-HRP were both 7.0. The high activities were available in a wider pH range than the free enzymes. 79.1% and 87.4% of initial activities remained after ten times uses of D380-GOX-HRP and PUR-GOX-HRP, respectively. The optimum reaction temperatures for them were both 45℃, at which temperature their relative activities were up to 132% and 141% higher than 25℃, respectively. The thermal stability of them was also enhanced.(3) Asymmetric synthesis of sulfoxide. Asymmetric oxidation of Thioanisole to sulfoxide catalyzed by D380-GOX-HRP and PUR-GOX-HRP were studied. The configuration of product was S. The best organic co-solvent was tert.-butyl alcohol. The optimal concentration of thioanisole and glucose were 2.0 mM and 5.0 mM. The optimal reaction temperatures were 30℃and 35℃, respectively. The optimal rotating speeds were 140rpm and 160rpm. Under the optimal conditions, the yield of the sulfoxide and ee were 93%, 58% for D380-GOX-HRP and 89%, 52% for PUR-GOX-HRP respectively. Using octyl polyglycoside instead of glucose as the substrate of GOX in the reaction of asymmetric synthesis of sulfoxide was proved to be feasible but needed further study.