TAAR-ZBE6
BCA Protein Assay Kit
The BCA Protein Assay is a detergent-compatible formulation based on bicinchoninicacid (BCA) for the colorimetric detection and quantization of total protein. This method combines the well-known reduction of Cu 2 to Cu 1 by protein in analkaline medium with the highly sensitive and selective colorimetric detection of the cuprous cation (Cu 1) using a unique reagent containing bicinchoninic acid. The purple-colored reaction product of this assay is formed by the chelation of two molecules of BCA with one cuprous ion. This water-soluble complex exhibits a strong absorbance at 562 nm that is nearly linear within creasing protein concentrations over a broad working range(20-2,000 μg/ml). The BCA method is not a true end-point method; that is, the final color continues to develop. However, following incubation, the rate of continued color development is sufficiently slow to allow large numbers of samples to be assayed together. The macromolecular structure of protein, the number of peptide bonds and the presence of four particular amino acids (cysteine,cystine, tryptophan and tyrosine) are reported to be responsible for color formation withBCA.2Studieswith di-, tri-and tetrapeptides suggest that the extent of color formation caused by more than the mere sum of individual color producing functional groups. Accordingly, protein concentrations generally are determined and reported with reference to standards of a common protein such as bovine serum albumin(BSA). A series of dilutions of known
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