Kessler R J, Fanestil D D
Anal Biochem. 1986 Nov 15;159(1):138-42. doi: 10.1016/0003-2697(86)90318-0.
Bicinchoninic acid forms the basis of an analytical method for the determination of protein. The reagent produces a purple complex with cuprous ion (Cu+) in an alkaline environment and is the basis for the monitoring of cuprous ions produced in the reactions of proteins with alkaline Cu2+. This method of protein determination was reported to have greater tolerance to many commonly encountered interfering compounds, when compared to the Lowry technique. However, we have found the bicinchoninic acid technique to produce erroneously high values for protein when common membrane phospholipids were included in the assay. Phospholipids in the presence of bicinchoninic acid produced an absorbance peak similar to that produced by protein. This absorbance was linear with concentration, however, the slope varied for individual phospholipids. The combined absorption of phospholipid and protein was not strictly additive. The results indicate that the presence of appreciable quantities of lipid in samples can cause significant error in the analysis of protein by the bicinchoninic acid procedure.
二辛可宁酸构成了一种测定蛋白质的分析方法的基础。该试剂在碱性环境中与亚铜离子（Cu⁺）形成紫色络合物，是监测蛋白质与碱性Cu²⁺反应中产生的亚铜离子的基础。据报道，与洛瑞法相比，这种蛋白质测定方法对许多常见的干扰化合物具有更高的耐受性。然而，我们发现，当测定中包含常见的膜磷脂时，二辛可宁酸技术会产生错误的高蛋白质值。在二辛可宁酸存在下，磷脂产生的吸收峰与蛋白质产生的吸收峰相似。这种吸收与浓度呈线性关系，然而，不同磷脂的斜率有所不同。磷脂和蛋白质的联合吸收并非严格相加。结果表明，样品中存在大量脂质会导致二辛可宁酸法分析蛋白质时出现显著误差。
