Alternative methods for fixing and staining gliadins in polyacrylamide gels.

Staining efficiencies of Coomassie Brilliant Blue G-250 (CBB G-250) and Coomassie Brilliant Blue R-250 (CBB R-250) in various media were studied in efforts to reduce or eliminate requirements for trichloroacetic acid (TCA). Stained gels were compared with gels stained with CBB R-250 in 12% TCA and evaluated for overall stain and background. Because of qualitative effects, stain intensities of low- and high-mobility gliadins were also evaluated. Results indicated gliadins are fixed under a wide range of conditions, permitting adjustment of conditions to provide optimum staining. CBB G-250 and R-250 in tap water fixed and stained most gliadins. Best results were obtained with CBB G-250 in 2% TCA, in 2% TCA containing 5% sodium sulfate, and in 2% and 5% phosphoric acid containing 5% sodium chloride or 5% sodium sulfate. Gels stained in these media were more easily observed during staining and more easily destained than gels stained in CBB R-250 in 12% TCA.