Blue of Coomassie

The blue of Coomassie (also called Brilliant Blue , Brilliant Blue G , Acid Blue 90 , C.I. 42655 , or Brilliant Blue G 250 ) is a coloring blue commonly employed in electrophoresis on polyacrylamide gel with sodium dodécyl sulfate (SDS-PAGE). Freezing is soaked in the dye during 30 minutes, before being disencumbered about it thirty minutes or more. This allows the visualization of bands, indicant the content of Protéines gel. The visualization of freezing contains usually a " marqueur" , which contains proteins of known molecular weight, which makes it possible to evaluate the molecular weight of proteins of the solution or fabric to be tested.

Use in laboratory

The blue of Coomassie binds supposément to proteins via Physisorption with the basic amino-acids (mainly the arginine) and with the aromatic ones. The blue of Coomassie is constituent integral of the Méthode of Bradford, making it possible to determine the protein concentration of a solution, in so far as one knows the sequence of his amino-acids. This method is based on the physicochemical properties of blue of Coomassie, an acid solution whose initial absorptance of 465 Nm becomes of 595 Nm when it is related to proteins. The data of absorptance can be used with the Loi of Beer in order to determine the protein concentration like their rate in a given solution.

Formulate solutions of color and washing

Solution of color:

2.5 G of blue of Coomassie,

455 ml of Methanol,

455 ml of distilled and deionized water (ddH2O),

90 ml of acid crystalline acetic (GAA)

(the ethanol replaces advantageously methanol because much less toxic)

Solution of washing (discoloration):

455 ml of methanol,

455 ml of ddH2O,

90 ml of GAA

(although washing draws being carried out with water, while heating)

A solution acetic ethanol 10% acid 10% very effective is especially heated (passage with the microwawe oven of a few minutes) and much less toxic than methanol.

Traditional formula of the reagent of Bradford

0.01% of blue of Coomassie,

4.7% of ethanol,

8.5% of phosphoric acid, in ddH2O.

Name

As for much of dyes, the blue of Coomassie holds its name of the African locality of Kumasi, currently in the territory of the Ghana; it was developed like dyeing for acid wool, and was named in commemoration of the British occupation of the capital of Ashanti in 1896, then called Coomassie.

External bonds

Coomassie Blue Staining off SDS-PAGE - Recipes and Protocol
Coomassie Blue: ingredients and procedure
Blue-commercial Coomassie source

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