Preparation of a reusable strip of barley oxalate oxidase for determination of urinary oxalate

Abstract

A reusable strip of oxalate oxidase was prepared by immobilizing covalently, a partially purified barley oxalate oxidase on alkylamine glass beads affixed on a plastic strip with a non-reactive fixative. The immobilized enzyme gave a conjugation yield of 9.5 mg g^-1 support with 84.8% retention of initial activity of free enzyme. A method for discrete anaysis of oxalate in urine was developed employing this enzyme strip. The method is based on measurement of H₂O₂ generated from urinary oxalate by strip bound oxalate oxidase by Trinder's colour reaction. The minimum detection limit of the method was 0.9μg 0.1 mL^-¹

urine. The recovery of added oxalate was 84.7%.WIthin and between assay co-efficient of variation were <7.3%<i> </i>and < 15.6% respectively. A fair correlation (r=0.752) was found between oxalate values obtained by a commercial kit method and present method. The method provides enormous ease in handling of immobilized enzyme during its reuse and is unaffected by Cl^-1 found in biological fluids.