The dye molecules bind to proteins including wool (keratin) to form a protein–dye complex. The formation of the complex stabilises the negatively charged anionic form of the dye producing the blue colour, even under acid conditions when most of the molecules in solution are in the cationic form.[1] This is the basis of the Bradford assay which is a protein determination method that involves the Coomassie Brilliant Blue dye binding to proteins. The binding of the dye to a protein causes a shift in the absorbance maximum of the dye from 465 to 595 nm.