Protein bands stained using this protocol can be detected within 5 to 10 min after adding rapid Coomassie staining solution. Because the Coomassie blue concentration is lower than that used in Basic Protocol 1, the gel background never stains very darkly and the bands can be seen even while the gel remains in the staining solution. Another difference is that isopropanol is substituted for methanol in the fixing solution. This method is slightly less sensitive than the standard procedure (see Basic Protocol 1).
Additional Materials (also see Basic Protocol 1) Isopropanol fixing solution (see recipe) Rapid Coomassie blue staining solution (see recipe) 10% (v/v) acetic acid
1. Place a polyacrylamide gel in a plastic or glass container. Cover the gel with 3 to 5 gel volumes isopropanol fixing solution and shake gently at room temperature. For a 0.7-mm-thick gel, shake 10 to 15 min; for a 1.5-mm-thick gel, shake 30 to 60 min.
2. Pour out fixing solution. Cover the gel with rapid Coomassie blue staining solution and shake gently until desired intensity is reached, 2 hr to overnight at room temperature.
Bands will become visible even in the staining solution within 5 to 30 min, depending on gel thickness. The gel background will never stain very darkly.
3. Pour out staining solution. Cover the gel with 10% acetic acid to destain, shaking gently >2 hr at room temperature until a clear background is obtained.
4. If necessary, pour out 10% acetic acid and add more. Continue destaining until clear background is obtained. Store gel in 7% acetic acid or water, or in plastic wrap at 4°C.
It is usually unnecessary to add additional destaining solution.
5. If desired, photograph (see Support Protocol 1) or dry (see Basic Protocol 1, step 7) the gel.
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