Guest
Coomassie brilliant blue is the name of two similar triphenylmethane dyes that were developed for use in the textile industry but are now commonly used for staining proteins in analytical biochemistry. Coomassie brilliant blue G-250 differs from Coomassie brilliant blue R-250 by the addition of two methyl groups. The suffix “R“ in the name of Coomassie brilliant blue R-250 is an abbreviation for “red“ as the blue colour of the dye has a slight reddish tint. For the “G“ variant the blue colour has a more greenish tint. The “250“ originally denoted the purity of the dye. Ponceau S, Acid Red 112, is a sodium salt of a diazo dye of a light red color, that may be used to prepare a stain for rapid reversible detection of protein bands on nitrocellulose A nitrocellulose membrane stained with Ponceau S dye for protein detection during western blotting. The blue bands on the left are protein markers for various molecular weights. Crystal violet The dye is used as a histological stain, particularly in Gram staining for classifying bacteria. When conducting DNA gel electrophoresis, crystal violet can be used as a nontoxic DNA stain as an alternative to fluorescent, intercalating dyes such as ethidium bromide. Used in this manner, it may be either incorporated into the agarose gel or applied after the electrophoresis process is finished. Used at a % concentration and allowed to stain a gel after electrophoresis for 30 minutes, it can detect as little as 16 ng of DNA. Ethidium bromide is commonly used as a non-radioactive marker for identifying and visualizing nucleic acid bands in electrophoresis. It fluoresces readily with a reddish-brown color when exposed to ultraviolet. light, intensifying almost 20-fold after binding to DNA. Problem: Which of these dyes could you use to visualize DNA run on an agarose gel? A) Coomassie blue B) Ponceau S C) Crystal violet D) Ethidium Bromide
