NUCLEOSIDE OXIDASE-MODIFIED CARBON PASTE ELECTRODE CONTAINING QUINONE - CATHODIC CURRENT RESPONSE TO NUCLEOSIDES

The cathodic current for the reduction of benzoquinone at a glassy carbon electrode was increased in the presence of nucleoside oxidase and inosine. This was attributed to the regeneration of benzoquinone from hydroquinone by the laccaselike reaction of the enzyme, the rate of which depended on the concentration of inosine in the solution. Accordingly, an enzyme electrode for nucleosides was constructed by immobilizing nucleoside oxidase behind a dialysis membrane on a carbon paste electrode containing p-benzoquinone or hydroquinone. The current response of the electrode to nucleosides was studied, and the results were discussed on the basis of the laccaselike activity of the enzyme. The nucleoside oxidase-modified electrode was tested as an amperometric enzyme electrode for nucleosides and could be used at least for three weeks.