Bradford assay

The Bradford assay is a colorimetric method used to determine the protein content in a solution. The solution is stained with Coomassie blue and an absorption spectrum recorded at 595 nm. Since the absorption is proportional to the amount of dye bound and hence the amount of protein in the solution the absorption can be compared to a solution of known protein (i.e. BSA) concentration. Therefore the absorbances of samples with different BSA concentrations are measured and the absorbances plotted against the protein concentrations. A standard curve is fitted through the data points and the absorbance of the unknown protein is then matched with the respective concentration in the curve.

Figure 1: BSA standard curve.