Determine the concentration of a protein in solution photometrically using the Biuret and Lowry assays. In the Biuret assay the protein forms a coloured complex with copper in alkaline solution and the intensity of the colour depends on the number of peptide bonds present in the protein.
In the Lowry assay the colour formed is due to a reaction between alkaline copper and protein as in the Biuret assay followed by the reduction of phosphomolybdate by the amino acids tyrosine and tryptophan.
