Principle of the Procedure

The Ready-to-Use BCA Protein Assay Kit is based on the principle that, under alkaline conditions, peptide bonds in protein molecules reduce divalent copper ions (Cu²⁺) to monovalent copper ions (Cu⁺). The Cu⁺ ions then react with BCA molecules to form a purple-colored complex. This complex can be detected at wavelengths of 540–590 nm, with maximum absorbance at 562 nm.

Within a certain concentration range, the color intensity of the reaction is linearly proportional to the protein concentration. Therefore, protein content can be determined based on the absorbance value. The BCA assay is rapid, sensitive, stable, and reliable, with very low coefficients of variation for the detection of different types of proteins, making it widely favored by researchers and laboratory professionals.

The BCA method is not affected by most chemicals present in samples. In tissue and cell lysis experiments, it has good compatibility with detergents such as SDS, Triton X-100, Tween 20, and Tween 80 at concentrations of up to 5%. However, the assay is susceptible to interference from chelating agents (EDTA, EGTA), reducing agents (DTT, β-mercaptoethanol), and lipids.

This kit contains a series of protein standard solutions (BSA solutions) at different concentrations. The standards are ready to use and do not require dilution, making the assay convenient and efficient.