Effect of deglycosylation of N-linked sugar chains on glucose oxidase from Aspergillus niger

Abstract

Endo-β-N-acetylglucosaminidase from Flavobacterium sp. released about 30% of the N-linked sugar chains from the glucose oxidase of Aspergillus niger. To elucidate the role of the carbohydrate moiety, the enzymatic properties of native and carbohydrate-depleted glucose oxidases were compared. It was found that their catalytic activities and thermal and pH stabilities were identical. However, the carbohydrate-depleted glucose oxidase was more rapidly precipitated by the addition of trichloroacetic acid and ammonium sulfate than the native enzyme. These results show that the N-linked sugar chains of the glucose oxidase contributed to the high solubility of the enzyme in water.Key words: glucose oxidase, Aspergillus niger, carbohydrate depletion, endo-β-N-acetylglucosaminidase, enzyme stability.