Glucose oxidase oxidation with periodate

D-Glucose Oxidases.—Oxidation of the D-glucose oxidase from Aspergillus niger with periodate decreased its carbohydrate content, but the catalytic activity, immunological reactivity, and gross secondary and quaternary structures were not aff ected. The periodate-oxidized derivative was stable to heat treatment, although its stability was reduced in the presence of denaturants. 

D-Glucose Oxidase.— The carbohydrate moieties of D-glucose oxidase from Aspergillus niger have been modified by oxidation with periodate ion. Although ca. 60% of the carbohydrate residues were oxidized at pH 5.6, none of the amino-acid residues was oxidized. The oxidized enzyme retained its full activity and was converted into an immobilized form. 

Oxidation of A. niger D-glucose oxidase with periodate indicated that the carbohydrate component (12% by weight) stabilizes the protein, although it has neither catalytic nor immunological activity and is not involved in maintaining the conformation of the molecule. ... 

In a study of the periodate oxidation of r>-glucose oxidase from Aspergillus niger, 50% of the carbohydrate was removed with little effect on enzymic activity. Gel permeation chromatography results suggested that the oxidized enzyme exists as a complex oligomerizing system. 

To avoid interference with the active site of the enzyme, D-glucose oxidase from Aspergillus niger has been immobilized by way of its carbohydrate moieties. Thus, treatment of the periodate-oxidized enzyme with a styrene derivative afforded a water-insoluble material retaining full enzymic activity and exhibiting enhanced thermal stability at 60 °C. 

---