Determination of Urinary Oxalate Using Banana Oxalate Oxidase: Comparison with Immobilized Enzyme

Oxalate oxidase, isolated from banana fruit peel, is immobilized on various supports and the efficacies of these derivatives in determining urinary oxalate are compared. Banana oxalate oxidase, when complexed with its antiserum, is found to have higher specific activity, greater stability, broader range of pH profile and higher resistance to thermal inactivation. Oxalate oxidase, when immobilized in acrylamide membrane strip, is found to be stable and easy to use in the determination of urinary oxalate. These two preparations compare well with that of soluble enzyme in sensitivity, accuracy and reliability. However, both hydrazide bead-linked oxalate oxidase and ethylene maleic anhydride derivative of oxalate oxidase are found to be unsuitable for the determination of urinary oxalate.