A combined Coomassie blue-silver stain method has been developed in sodium dodecyl sulfatepolyacrylamide gels for the detection of proteins using the model compounds bovine serum albumin, lysozyme, and recombinant DNA-derived human insulin. Sensitivity was enhanced 2.2 to 8.6 times by the new method relative to that of silver staining alone. The new method may also be useful in enhancing detection sensitivities of other proteins. o 1985 Academic POW+, IW.
KEY WORDS: gel electrophoresis; proteins; gel staining; silver staining; combined Coomassie blue-silver staining: Coomassie blue staining. *I. Soak electrophoresis gel three times for 20 min in 40% methane!-10% acetic acid (400 ml/gel).
-
Stain with Coomassie blue G-250 for 30 min (200 ml/gel).
-
Destain three times for 10 min with 5% TCA (400 ml/gel). 4. Soak two times for 10 min in 40% methanol-IO% acetic acid (400 ml/gel). *5. Soak two times for 10 min with 10% ethanol-5% acetic acid. *6. Soak for 10 min in 3.4 mM potassium dichromate-O.0032 N nitric acid (200 ml/gel, 25Β°C). *7. Wash with deionized water three times for 10 min (400 ml/gel, 25Β°C). *8. Soak for 30 min in 0.012 M silver nitrate (200 ml/gel, 25Β°C). '9. Wash with deionized water for 2 min (400 ml/gel). *lo. Develop three times with 0.28 M sodium carbonate-O.5 ml of formahn per liter for 1, 5, and 3 min, respectively (200 ml/gel, 25Β°C). *I 1. Stop with 5% acetic acid for 5 min; then immerse the gel in deionized water.