Preparation of a very stable immobilized biocatalyst of glucose oxidase from Aspergillus niger

Glucose oxidase (GOX) has been immobilized on different activated supports, including glyoxyl agarose, epoxy sepabeads and glutaraldehyde-activated supports. Immobilization onto supports pre-activated with glutaraldehyde rendered the most thermo-stable preparation of GOX. Therefore, as the glutaraldehyde chemistry gave a high stabilization of the enzyme, we proposed another technique for improving the multipoint attachment through glutaraldehyde: the enzyme was ionically adsorbed on cationic supports with primary amino groups and then the immobilized preparation was treated with a glutaraldehyde solution. The decrease on enzyme activity was <20%. Following this methodology, we achieved the highest stability of all the immobilization systems analyzed, showing a half-life 100 times higher than the soluble enzyme. Moreover, this derivative showed a higher stability in the presence of organic solvents (for instance methanol) or hydrogen epoxide than the ionically adsorbed enzyme or the soluble one. Therefore, the adsorption of GOX on aminated cationic support and subsequent treatment with glutaraldehyde was presented as a very successful methodology for achieving a very stable biocatalyst.