Coomassie Blue R-250 (CAS 6104-59-2)

Coomassie Blue R-250, with the chemical structure of C45H44N3NaO7S2 and a CAS number of 6104-59-2, is a synthetic, complex organic dye recognized primarily for its role in biochemical research, particularly in the analysis of protein composition. This dye belongs to the family of triphenylmethane dyes and is extensively utilized in a technique known as Bradford protein assay, a colorimetric assay in protein chemistry that quantifies the total protein concentration. The mechanism of action of Coomassie Blue R-250 involves its ability to bind to proteins predominantly via electrostatic interactions and Van der Waals forces. When the dye associates with protein molecules, particularly with basic amino acid residues such as arginine, lysine, and histidine, it undergoes a shift in its absorption spectrum. Typically, it shifts from red (when unbound) to an intense blue once bound to protein, allowing for the spectrophotometric detection of the proteins in solution. This shift is measurable and can be correlated to protein concentration using a standard curve of known protein standards. In research contexts, Coomassie Blue R-250 is also used in staining protocols for protein electrophoresis, such as SDS-PAGE, to visualize protein bands. This aids researchers in assessing protein purity, molecular weight, and composition without altering the biological activity of the proteins, making it an indispensable tool in molecular biology labs for both qualitative and quantitative analysis.