Crystal violet stains proteins in SDS-PAGE gels and zymograms

Coomassie brilliant blue R250, an anionic dye is the most popular stain to detect proteins resolved in SDS-PAGE gels. Crystal violet, a cationic dye was found to be versatile and stained proteins in SDS-PAGE gels and in zymograms. Stained proteins can be transferred to nitrocellulose and the stained proteins on the western detected with enzyme coupled antibodies. Staining can be reversed. Staining takes 3 h at RT or 30 min at 60 °C. Crystal violet stained some E. coli high and low molecular weight proteins not stained by Coomassie blue R250. Crystal violet stained down to 16 ng of protein, some five-fold lower than Coomassie blue, though the two stains had a similar linear dynamic range. The staining sensitivity could be increased to 2 ng when crystal violet and Coomassie blue were combined in a double staining/counterion dye formulation. The low concentrations of the dye without a destaining step reduces the costs of the technique and results in a more environmentally friendly stain compared to traditional staining methods.