The BCA Protein Assay Kit is a two-component, high-precision, detergent-compatible assay reagent set to measure total protein concentration compared to a protein standard. The BCA Protein Assay Kit is based on the formation of a Cu²⁺-protein complex under alkaline conditions, followed by reduction of the Cu²⁺ to Cu¹⁺ by cysteine, cystine, tryptophan, tyrosine, and peptide bonds. BCA forms a purple colored complex with Cu¹⁺ that is detectable at 562nm, and proportional to the protein present. The BCA Protein Assay can be used to assess yields in whole cell lysates and affinity-column fractions, as well as to monitor protein contamination in industrial applications. Compared to most dye-binding methods, the BCA Assay is affected much less by protein compositional differences, providing greater protein-to-protein uniformity.