Description
BCA (bicinchoninic acid) is a perfect protein assay method, it serves the purpose of the Folin reagent in the Lowry assay, namely to react with complexes between copper ions and peptide bonds to produce a purple end product. This method is favored by professionals for its high sensitivity, stability, reliability, and small variation coefficient on different kinds of protein detections. Determination of the protein concentration with BCA is not influenced by chemical substances in majority of the samples. For example, in tissue and cell lysate experiments, the test results were not affected by common detergents (SDS, Triton X-100, Tween), but will be influenced by chelant (EDTA, EGTA), deoxidizer (DTT, mercaptoethanol) and lipid. So, in the assay, if the background of the sample diluent buffer or lysis buffer is high, end user can try to use Bradford Protein Assay Kit (Catalog # BWR1027). This kit can work well here.
Principle: In an alkaline medium, Cu2+ was reduced to Cu+ by protein, and the purple-colored reaction product of this assay is formed by the chelation of two molecules of BCA with Cu+. This complex exhibits a strong absorbance at 562nm, and since the absorbancy strength is proportional to the protein concentration, determine the absorption value at 562nm, then compare with the standard curve, the protein concentration can be calculated