Coomassie Brilliant Blue R-250

Coomassie Blue R-250 is a triphenylmethane dye used extensively in SDS-PAGE for the analysis of proteins.

Brilliant Blue R has been used for many years for staining proteins on polyacrylamide electrophoresis gels. Improvement of sensitivity and background have been accomplished using Brilliant Blue dyes in a colloidal form. The Brilliant Blue R-Protein complex has an absorption maximum between 560 and 575 nm. (Scanning is usually done at 570 nm.) The staining intensity of proteins may be related to the basicity of the protein involved. Other applications for brilliant Blue R include use in detection of lipids in thin layer chromatography, determination of the CMC of detergents, and detection of proteins in solution, as well as on cellulose acetate plates. Coomassie Blue R-250 is additionally used in the Bradford Assay to quantify the concentration of protein in a solution, such as cell lysates. A fast acting, sensitive dye which can be used on SDS gels, IEF gels, and standard gels.

The dye molecule binds to proteins to form a protein-dye complex. This complex stabilizes the negatively charged anionic form of the dye producing the blue color, even under acidic conditions.

Prepare in distilled, deionized water: 50% (v/v) methanol, 0.05% (w/v) Coomassie Brilliant Blue R-250, 10% acetic acid, 40% Water. Dissolve the Coomassie Brilliant Blue R in methanol before adding acetic acid and water (filtration is not generally needed). Solution can be stored for 6 months. If precipitate is observed following prolonged storage, filter to obtain a homogeneous solution.