[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer m...[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer material by the embedding method,and the optimal immobilization conditions were obtained by single factor tests:CaCl_(2) concentration 2.0%,sodium alginate concentration 2.0%,immobilization time 2 h and mass ratio of enzyme to carrier 10 mg/100 g,under which the immobilized enzyme activity was 93.33 U/g.Under the above conditions,the properties of polyphenol oxidase immobilized by sodium alginate(A-PPO)and free polyphenol oxidase were studied.[Results]The thermostability of A-PPO was better than that of the free enzyme,but the pH stability of A-PPO was inhibited.The Michaelis constant K_(m) values of free polyphenol oxidase and A-PPO were 0.37 and 0.48 mmol/L,respectively,and the maximum reaction rate V_(max) values were 0.38 and 0.51 mmol/(L·g),respectively.[Conclusions]This study provides a theoretical basis for the study of the properties of polyphenol oxidase.展开更多
Magnetic polyvinyl alcohol (PVA) microspheres with 8—64 μm in diameter were prepared from PVA by dispersion and copolymerization with Fe3O4 as magnetite.There were more functional groups, such as hydroxyl and carbox...Magnetic polyvinyl alcohol (PVA) microspheres with 8—64 μm in diameter were prepared from PVA by dispersion and copolymerization with Fe3O4 as magnetite.There were more functional groups, such as hydroxyl and carboxyl etc. on the microsphere surface.1,1′-Carbonyldiimidazole (CDI), a carbonylating agent, was used for the activation of hydroxyl groups of PVA, and α-acetolactatedecarboxylase (ALDC) was immobilized onto the magnetic PVA microspheres by covalent bonding through the amino group.The results showed that total activity, protein binding, specific activity and activity retention of the immobilized enzyme were 63293 U·g -1, 72.67 mg·g -1, 870.96 U·mg -1 and 48.71%,respectively.The optimum temperature of immobilization enzyme was 50℃ and the optimum pH was 6.0.Compared with the free enzyme of ALDC, the thermal, operational and pH stability of the immobilized enzyme were improved.After being stored at 4℃, pH 6.0 for 31 days, the immobilized ALDC retained 95.7% of its initial activity which was 8% higher than the free enzyme.展开更多
基金Supported by Undergraduate Innovation and Enterpreneurship Training Program(202110514002)Huanggang Normal University High-level Cultivation Project(202108504).
文摘[Objectives]This study was conducted to investigate the effects of embedding conditions on activity and catalytic properties of immobilized polyphenol oxidase.[Methods]Polyphenol oxidase was immobilized in a polymer material by the embedding method,and the optimal immobilization conditions were obtained by single factor tests:CaCl_(2) concentration 2.0%,sodium alginate concentration 2.0%,immobilization time 2 h and mass ratio of enzyme to carrier 10 mg/100 g,under which the immobilized enzyme activity was 93.33 U/g.Under the above conditions,the properties of polyphenol oxidase immobilized by sodium alginate(A-PPO)and free polyphenol oxidase were studied.[Results]The thermostability of A-PPO was better than that of the free enzyme,but the pH stability of A-PPO was inhibited.The Michaelis constant K_(m) values of free polyphenol oxidase and A-PPO were 0.37 and 0.48 mmol/L,respectively,and the maximum reaction rate V_(max) values were 0.38 and 0.51 mmol/(L·g),respectively.[Conclusions]This study provides a theoretical basis for the study of the properties of polyphenol oxidase.
文摘Magnetic polyvinyl alcohol (PVA) microspheres with 8—64 μm in diameter were prepared from PVA by dispersion and copolymerization with Fe3O4 as magnetite.There were more functional groups, such as hydroxyl and carboxyl etc. on the microsphere surface.1,1′-Carbonyldiimidazole (CDI), a carbonylating agent, was used for the activation of hydroxyl groups of PVA, and α-acetolactatedecarboxylase (ALDC) was immobilized onto the magnetic PVA microspheres by covalent bonding through the amino group.The results showed that total activity, protein binding, specific activity and activity retention of the immobilized enzyme were 63293 U·g -1, 72.67 mg·g -1, 870.96 U·mg -1 and 48.71%,respectively.The optimum temperature of immobilization enzyme was 50℃ and the optimum pH was 6.0.Compared with the free enzyme of ALDC, the thermal, operational and pH stability of the immobilized enzyme were improved.After being stored at 4℃, pH 6.0 for 31 days, the immobilized ALDC retained 95.7% of its initial activity which was 8% higher than the free enzyme.
