Coomassie Blue stain is used to stain the protein bands in polyacrylamide gels. One common way to use it is to dissolve the dye in a mixture of methanol, acetic acid, and water. This stain will permeate the gel, stain the protein, and also fix the protein in place. It will also stain the whole gel so you can't see the protein bands. The dye binds more tightly to the proteins than the to the gel matrix, however, so the dye can subsequently be removed from only the protein-free parts of the gel using a similar solvent from which the dye is omitted. This is the destain. The result is a clear background with blue-stained protein bands.
Now it is possible to purchase colloidal Coomassie Blue. This reagent will stain the proteins without staining the gel, so it is not necessary to destain the gel in order to see the protein bands. For some, but not all, of the colloidal Coomassie Blue reagents, however, it is necessary to fix and wash the gel before adding the stain. I like to use Expedeon InstantBlue stain because you can just pour it onto the gel immediately after finishing the electrophoresis and watch as the protein bands appear - no fixing, washing, or destaining.
Coomassie blue is a colorant derived from triphenylmethane, widely used in biochemistry because of its affinity to proteins, another application are silver stains, so that once protein separation is achieved by its mass in a network of acrylamide- Bis acrylamide (because SDS has standardized the loads on your samples), you can visualize them, for which you must discolor your gels. Other applications such as zygographs, gels that use one or more substrates such as gelatine, show lysing properties (gelatinolysis) on the added substrate and to see you need to dye and fade your gels.
Coomassie Blue stain is used to stain the protein bands in polyacrylamide gels. One common way to use it is to dissolve the dye in a mixture of methanol, acetic acid, and water. This stain will permeate the gel, stain the protein, and also fix the protein in place. It will also stain the whole gel so you can't see the protein bands. The dye binds more tightly to the proteins than the to the gel matrix, however, so the dye can subsequently be removed from only the protein-free parts of the gel using a similar solvent from which the dye is omitted. This is the destain. The result is a clear background with blue-stained protein bands.
Now it is possible to purchase colloidal Coomassie Blue. This reagent will stain the proteins without staining the gel, so it is not necessary to destain the gel in order to see the protein bands. For some, but not all, of the colloidal Coomassie Blue reagents, however, it is necessary to fix and wash the gel before adding the stain. I like to use Expedeon InstantBlue stain because you can just pour it onto the gel immediately after finishing the electrophoresis and watch as the protein bands appear - no fixing, washing, or destaining.
Dear Dipika, silver staining and other fluorecent dyes are more sensitive than coomassie blue staining. Usually we use commercially available kits for silver staining from Bio-Rad or other manufacturers. In coomassie blue staining we prefer Thermo PAGE blue, easy staining procedure and more sensitive than lab-made coomassie blue staining procedure with very short destaining procedure.
Best regards.
Briefly, staining step with commassie or other dyes used for this purpose is to stain the protein bands. The gel also be stained, therefore you should de-stain the gel to reflect the protein bands with de-stained background.
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