Abstract:

The activity of oxalate oxidase (OxO, EC1.2.3.4) was detected in rice bran and this enzyme was found to be mainly rich in cell wall. The optimal reaction pH and Km values of this enzyme towards oxalate as a substrate were 2.5 and 0.63 mmol/L, respectively. An inhibitory effect against OxO was observed when oxalate concentration was over 2.0 mmol/L. Meanwhile, the enzyme exhibited high thermo-stability and resistance to SDS, pepsin and NaCl. Although EDTA, NH4+, Cl－, Mn2+, CO32－, Na+, K+, H2PO4 －, SO42 －, Fe2+ and PO43 － at the concentration of 1 mmol/L had no effect on OxO activity, NO3 －, Co2+, Zn2+, Cu2+, Mg2+, Ca2+and Al3+ at the identical concentration exhibited strong an inhibitory effect against OxO activity. Therefore, OxO from rice bran may be widely used to detect oxalate level, which will provide theoretical evidence for the ingredient analysis of functional foods.

Key words: oxalate oxidase, rice bran, property