Quantification of urinary oxalate by immobilized oxalate oxidase of forage sorghum leaf

A partially purified oxalate oxidase from leaves of 10-day-old seedlings of forage sorghum was immobilized covalently onto alkylamine glass beads affixed on inner base of a glass beaker. The enzyme retained 5.17% of its initial activity with a conjugation yield of 182 mg/g support. After immobilization, the enzyme showed an increase in its optimum pH and Km for oxalate but slight decrease in incubation temperature and time for maximum activity as compared to free enzyme. The glass beaker bound enzyme was employed for determination of urinary oxalate. The urinary oxalate in apparently healthy persons, as measured by the glass beaker, was found to be in the range of 12.5 to 29.7 mg/l (mean 20.9 mg/l) for females and 25.7 to 45.4 mg/l urine (mean 37.2 mg/l) for males. The glass beaker provided 70 reuses of immobilized enzyme with ease in handling.