Entrapment of Sorghum root oxalate oxidase into polyvinyl alcohol membrane

A Cl- and NO3- insensitive oxalate oxidase, purified from the roots of 10-day old seedlings of grain Sorghum has been immobilized on polyvinyl alcohol (PVA) membrane through entrapment with 96.07% retention of initial activity. The membrane bound enzyme showed an increase in optimum pH (from 5.0 to 6.5), time of incubation (from 5 to 10 min) and Km for oxalate (from 0.38 to 6.23 mM), but decrease in incubation temperature for maximum activity (from 37 to 30 degrees C) and Vmax (from 70 nmol/min/ml to 9.7 nmol H2O2/min) and was unaffected by Cl- and NO3. The membrane bound enzyme lost 50% of its initial activity after 30 days of storage at room temperature. The use of membrane bound oxalate oxidase in determination of serum oxalate of urinary stone patients is demonstrated.