Enzymatic Properties of Xanthine Oxidase and Its Covalent Immobilization on Different Supports

Abstract:

The enzymatic properties of xanthine oxidase(XOD) from Arthrobacter M3 were first investigated,and then modified sepharose 4B mediums and macroporous ion exchange resins were used to immobilize XOD in order to enhance the enzyme stability. The results showed that this enzyme was a heterodimer with a molecular weight of 135 000. The optimal reaction temperature and pH for XOD were 37 ℃ and 7.5,respectively. The stabilities of the covalently immobilized XOD on the modified sepharose 4B mediums were higher than that on macroporous ion exchange resins. Furthermore,the immobilized XOD on sepharose 4B-glutamate medium(Sepharose-Glu) showed the optimum stability. After incubation at 50 ℃ for 3 h,the immobilized XOD on Sepharose-Glu medium still maintained 48.3% of its initial activity,and the half-life of this immobilized enzyme increased by 160% compared to the free enzyme. In addition,acid-alkali tolerance of this immobilized XOD was also improved.