Development of color in Coomassie dye-based protein assays
has been associated with the presence of certain basic amino
acids (primarily arginine, lysine and histidine) in the protein. Van
der Waals forces and hydrophobic interactions also participate
in the binding of the dye by protein. The number of Coomassie
dye ligands bound to each protein molecule is approximately
proportional to the number of positive charges found on the
protein. Free amino acids, peptides and low molecular weight
proteins do not produce color with Coomassie dye reagents. In
general, the mass of a peptide or protein must be at least 3,000
daltons to be assayed with this reagent. In some applications this
can be an advantage. The Coomassie (Bradford) Protein Assay
has been used to measure “high molecular weight proteins”
during fermentation in the beer brewing industr