Protein Determination is one of the most common operations performed in biochemical research. The principle of the bicinchoninic acid (BCA) assay is similar to the Lowry procedure, in that both rely on the formation of a Cu²⁺-protein complex under alkaline conditions, followed by reduction of the Cu²⁺ to Cu¹⁺. The amount of reduction is proportional to the protein present. It has been shown that cysteine, cystine, tryptophan, tyrosine, and the peptide bond are able to reduce Cu²⁺ to Cu¹⁺. BCA forms a purple-blue complex with Cu¹⁺ in alkaline environments, thus providing a basis to monitor the reduction of alkaline Cu²⁺ by proteins at absorbance maximum 562 nm. The BCA assay is more sensitive and applicable than either Biuret or Lowry procedures. In addition, it has less variability than the Bradford assay. The BCA assay has many advantages over other protein determination techniques:

• The color complex is stable.
• There is less susceptibility to detergents.
• It is applicable over a broad range of protein concentrations.

Components
  Bicinchoninic Acid Solution
  4% (w/v) CuSO 4 • 5H2O Solution
  Protein Standard Solution

BCA Protein Compatibility Chart

Ordering Information

Product #	Product Name	Size
BCA-1	Bicinchoninic Acid Kit for Protein Determination	1 kit
B9643	Bicinchoninic Acid Solution	1 L
D8284	Bicinchoninic Acid Disodium Sal	1 g 5 g 10 g 25 g
C2284	Copper (II) Sulfate Solution	25 mL

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