DETERMINATION OF TOTAL PROTEIN BY USING PURIFIED HUMAN SERUM PROTEIN FRACTIONS

四种常用的低浓度测定方法的比例偏倚 用人蛋白质级分（Cohn 级分II、III、IV和V）。 每个组分都被分配了一种蛋白质 使用缩二脲法测定的浓度值 纯化的人血清白蛋白单体，以建立校准。 所有 四种方法（考马斯蓝染料结合，Lowry等人，紫外 吸收和免疫比浊法）给出了可接受的结果， 组分V（白蛋白）。 紫外吸收法和Lowry法 高估了三种球蛋白组分（II、III和IV）， 考马斯亮蓝染料结合法和免疫光度法 低估了这些球蛋白组分。 最小比例偏差 球蛋白组分采用Lowry法。

The proportional bias of four methods frequently used for determining low concentrations of protein was evaluated with human protein fractions (Cohn Fractions II, III, IV and V). Each fraction was assigned a protein concentration value which was determined by the biuret method using purified human serum albumin monomer to establish the calibration. All four methods (Coomassie blue dye-binding, Lowry et al., ultraviolet absorption, and the immunoephelometric) gave acceptable results for fraction V (albumin). The ultraviolet absorption and the Lowry methods overestimated the three globulin fractions (II, III, and IV) and the Coomassie blue dye-binding and the immunoephelometric methods underestimated these globulin fractions. The least proportional bias for the globulin fractions was with the Lowry method.