A modified Coomassie blue staining of proteins in polyacrylamide gels with Bismark brown R.

A rapid and sensitive protein staining method employing a mixed dye technique has been developed. Solutions of Coomassie brilliant blue R-250 (CB, 0.2%) and Bismark brown R (BBR, 0.05%) were mixed in the volume ratio of 1:0.75 for staining (final molar ratio, 4.5:1). In this staining, BBR inhibits the binding of CB to gel matrix by forming ion-pairing complex with excess CB; therefore, it reduces staining/destaining times and also enhances the staining effect of CB on protein band. As a result, the mixed dye staining enables complete staining/destaining within 20/25 min and detection of up to 25 ng of bovine serum albumin.