Discrete analysis of plasma oxalate with alkylamine glass bound sorghum oxalate oxidase and horseradish peroxidase

We have reported a simple method of determination of plasma oxalate using a Cl- and NO3- insensitive oxalate oxidase purified from grain sorghum leaf and commercially available peroxidase from horseradish [Pundir et al., Ind. J. Biochem. Biophys., 35 (1998) 120-122]. The present report describes the immobilization of both the enzymes onto alkylamine glass, their kinetic pr operties and. application for discrete analysis of plasma oxalate. In the a nalytic method, H2O2 generated from plasma oxalate by immobilized oxalate o xidase is measured colorimetrically at 520 fim by oxidative coupling with 4 -aminophenazone, and phenol catalyzed by immobilized peroxidase. The minimu m detection limit of the method is 2.5 mu mol/l. Analytic recovery of added oxalate in plasma was 89.5+/-4.1% (mean+/-S.D.). The within and between da y CV for plasma oxalate measurement were <9.37 and <11.08, respectively. Th e normal range of plasma oxalate as measured by the present method was 3.6 to 5.7 mu mol/l. The method is not only free from interference by plasma Cl - and NO3- but also provides the reuse of glass beads and thus reduces the cost of analysis for routine. (C) 2000 Elsevier Science B.V. All rights res erved.