What is the absorption maximum of free and protein-bound dye Coomassie R-250?
When dissolved in 0.01 M citrate buffer at pH 3.0, it has an absorption maximum at 555 nm; the protein-dye complex is characterized by a peak slightly broader than that of the free dye with an absorption maximum at 549 nm.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
To what amino acids does Coomassie R-250 bind?
In acidic conditions, Coomassie dye primarily binds basic amino acids (arginine, lysine and histidine).
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
How do I prepare a solution of Coomassie R-250 dye?
Add 100 mL of glacial acetic acid to 450 mL distilled water.
Dissolve 3 g of Coomassie R-250 dye in 450 mL methanol.
Mix the acetic acid and methanol solutions.
Filter the solution before use.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
Is Coomassie Brillant Blue R-250 available already prepared in solution?
Yes, Imperial Protein Stain (Cat. Nos. 24615 (1L) and 24617 (3 x 1L) is a ready-to-use colorimetric stain formulated with Coomassie R-250 dye that delivers consistent nanogram-level detection of proteins in polyacrylamide electrophoresis gels.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.
What are the differences between R-250 and G-250 Coomassie Dyes?
Coomassie G-250 has an additional methyl group on the lower two central rings in the structure, as compared to Coomassie R-250. Bands stained with Coomassie R-250 are reddish-purple in color; Coomassie G250 bands are greenish-blue in color.
Sometimes referred to as colloidal Coomassie Blue, the G-250 form differs from R-250 in more readily forming dye-dye aggregates in solution. Consequently, G-250 interacts more weakly with polyacrylamide gel matrix than with itself, resulting in lower background that can be more easily washed away.
Find additional tips, troubleshooting help, and resources within our Protein Assays and Analysis Support Center.