Coomassie Brilliant Blue Stain is supplied by HiMedia. It is available in the form of a blue coloured solution. Coomassie Brilliant Blue Stain is a Coomassie G-250 methanol-based stain formulated for protein detection in polyacrylamide gel. Protein bands form an intense blue colour when stained with Coomassie Brilliant Blue and can be easily distinguished on the gels. This staining is very convenient as it involves a single, ready-to-use reagent and does not modify the target proteins. It is composed of 0.25% (w/v) Coomassie Brilliant Blue G-250 in 45% (v/v) methanol and 10% (v/v) glacial acetic acid. It is advisable to store this product between 15-25C.

Coomassie Brilliant Blue G is a very common dye with two similar triphenylmethane groups and is widely used as a staining solution for visualizing proteins on polyacrylamide gels after electrophoretic separation. In acidic condition this dye binds to basic and hydrophobic residues of proteins and changes colour from reddish brown to intense blue and as a result protein samples are visualized as blue bands on the gels. During the staining procedure gels are not required to be fixed as this solution contains methanol and acetic acid. One initial water wash step is required for the removal of residual SDS (during SDS-PAGE) as it interferes with the staining procedure. Staining is usually done for an hour and then a methanol: acetic acid de-staining step is required for washing off excess unbound dye from the gel. Coomassie Brilliant Blue Stain is used for the detection of protein bands on acrylamide gel while doing SDS-PAGE. During this staining procedure proteins are not chemically modified and therefore, the protein bands can be completely de-stained and recovered for sequencing.