Coomassie Blue Stains

Coomassie Brilliant Blue is a chromogenic dye that associates electrostatically with the amino and carboxyl groups of proteins. A triphenylmethane compound, this dye is insoluble in water. For protein gels, the recipe for a Coomassie Blue gel staining solution is generally prepared in a mixture of 50% methanol, 10% acetic acid, and 40% water. The gel is then soaked in this stain between 1-4 hours with agitation. Commercial variants of this stain are available that may feature shorter staining durations.