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Abstract
Carboxyl groups on a collagen membrane were activated with the aid of an acyl-azide reaction. the enzyme oxalate oxidase, prepared from barley seedlings, was subsequently immobilized on the activated collagen film. the specific activity and the Michaelis constant were 0.13 units/cm2 and 0.1 M, respectively. Enzyme activities were determined as function of pH, ionic strength, and ambient chloride concentration, intercomparing the enzyme in aqueous solution with its immobilized counterpart. Oxalate was quantitated amperometrically via electrooxidation of the hydrogen peroxide by-product generated in the reaction between oxalic acid and O2. the detection limit of oxalate was 10−5, which yielded a current of 2 nanoampere.