cerectrophtain dyes interact with virtually all proteins to yield a protein-dye conjugate that absorbs light differently than the dys alone(there is a significant increase in the light absorption)this chhange in absorption can be quantified with a spectrotometer and is the basis of an indirect measure of the amount of protein in a sample in this procedure protein containing solutions will be exposed to a dye molecule called coomassie blue g-250 the interaction of coomassie blue g-250 with protein molecules produces an intensely blue complex