Bradford Reagent

Bradford Reagent contains a dye, Coomassie brilliant Blue G-250, which has an absorbance maximum of 465 nm in unbound state. The Bradford protein assay is based upon the formation of complexes between Coomassie Brilliant Blue G-250 and the protein samples in solution. When the protein sample binds to the dye the color of the solution turns blue from brown and there is a shift in the absorption maximum of the dye from 465 nm to 595 nm. This dye binding procedure is completed within 5 minutes and the blue colored complex formed is stable for one hour. Thus concentration of unknown protein sample can be derived by plotting its absorbance value on the standard curve. The standard curve is obtained from the absorbance readings of the series of standard protein dilutions assayed alongside the unknown sample.