Biuret Protein Assay

The soluble protein content of a sample is often used in enzyme activity calculations. In addition, soluble protein content is also used for quality analysis such as food. In a strong alkaline solution, biuret forms a purple complex with CuSO4; the color of the purple complex is proportional to the protein concentration and has nothing to do with the protein molecular weight and amino acid composition, so it can be used to determine the protein content. This method is suitable for samples with high protein concentrations.