Amperometric response to reducing carbohydrates of an enzyme electrode based on oligosaccharide dehydrogenase. Detection of lactose and α-amylase

A mediated amperometric enzyme electrode, which was constructed by immobilizing oligosacharide dehydrogenase behind a dialysis membrane on the surface of a carbon paste electrode containing p-benzoquinone, showed a current response to d-xylose, d-galactose, d-mannose, lactose, maltose, maltotriose, maltopentaose and maltohexaose. The sensitivity of the current response to these carbohydrates was dependent on the kinetics of the immobilized enzyme reaction and/or the permeation rate of the substrate through the dialysis membrane. Hence the sensitivity could be varied by controlling the amount of the immobilized enzyme and the thickness of the dialysis membrane. The time dependence of the current response ofthe enzyme electrode with a large amount of the immobilized enzyme and a thicker dialysis membrane could be explained by an equation describing diffusion of the substrate in the membrane. The enzyme electrode was used to measure lactose in milk and to assay α-amylase in standard serum.