活性污泥胞外聚合物中蛋白质定量方法的评价

Evaluation of protein quantification methods for extracellular polymers in activated sludge

胞外聚合物(EPS)中蛋白质的准确定量对研究活性污泥性质具有重要意义。为对EPS中蛋白质定量方法的选择提供依据,系统评价了Modified Lowry法、BCA法、Bradford法的测试性能,包括测试范围、准确度、精密度及对EPS中部分组分(Ca^2+、Mg^2+、还原性糖、腐殖酸)的抗干扰性。结果表明:Modified Lowry法在蛋白质浓度为1~10、10~100 mg/L时与吸光度的线性相关性较好(R2>0.99),BCA法和Bradford法的测试范围较Modified Lowry法更宽;Modified Lowry法的准确度和精密度均最高,BCA法次之,Bradford法最低;Modified Lowry法受Ca^2+、Mg^2+和还原性糖干扰,BCA法受还原性糖和腐殖酸干扰,Bradford法受腐殖酸的干扰。因此,EPS中蛋白质定量方法的选择应从样品性质(蛋白质浓度范围、干扰物质种类及浓度)和测试方法性能(测试范围、准确度、精密度和抗干扰性)2个方面综合考虑。

The accurate quantification of proteins in extracellular polymeric substances(EPS)is of great significance for studying the properties of activated sludge.To provide a basis for the selection of protein quantification methods in EPS,the test performance of Modified Lowry method,BCA method,Bradford method was systematically evaluated,including the test range,accuracy,precision and the anti-interference of some components(Ca^2+,Mg^2+,reducing sugar and humic acid)in EPS.The results indicated that the Modified Lowry method showed a good linear correlation between protein concentration and absorbance in the range of protein concentration of 1-10 and 10-100 mg/L(R2>0.99);and the test range of BCA method and Bradford method was wider.Modified Lowry method had the highest accuracy and precision,BCA method ranked the second,and Bradford method was the worst.Besides,Modified Lowry method was affected by Ca^2+,Mg^2+and reducing sugar;BCA method was affected by reducing sugar and humic acid;and Bradford method was affected by humic acid.Therefore,the choice of protein quantification method in EPS should be comprehensively considered from the two aspects of sample properties(protein content range,interference species and concentration)and test method performance(test range,accuracy,precision and anti-interference).