Purification and characterization of oxalate oxidase from wheat seedlings

Oxalate oxidase (OxO, EC 1.2.3.4.) was purified to homogeneity from wheat (Triticum aestivum) seedlings by sequential thermal treatment, ultrafiltration, Sephadex G-100 gel filtration and affinity chromatography with concanavalin A. The enzyme was purified 66.11-fold with a recovery of 21.97%. It showed a subunit molecular mass of 32.6 kDa on SDS-PAGE and a native molecular mass of 170 kDa on Sephadex G-150 filtration, suggesting that it is a pentamer. The wheat OxO had a maximum activity at pH 3.5. Its K _m for oxalate was 0.21 mM. Chemical modification revealed that cysteine, lysine and carboxylate residues were essential for OxO activity, whereas arginine, serine, threonine and tryptophane residues were not essential.