【摘要】 在水稻谷糠中检测到草酸氧化酶(OxO,EC1.2.3.4)的活性,其主要存在于细胞壁中,最适pH值为2.5,Km值为0.63mmol/L,当底物草酸的浓度大于2.0mmol/L时会出现底物抑制;此外,该酶热稳定性很高,而且对胃蛋白酶、SDS和高浓度的NaCl不敏感;1mmol/L的EDTA、NH4+、Cl-、Mn2+、CO32-、Na+、K+、H2PO4-、SO42-、Fe2+和PO43-对其活性没有影响,但1mmol/L的NO3-、Co2+、Zn2+、Cu2+、Mg2+、Ca2+和Al3+会抑制它的活性。因此,谷糠中的OxO可能被广泛用于测定草酸含量。更多还原

【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.更多还原