Coomassie Brilliant Blue

Coomassie Brilliant Blue R-250

Names
Other names C.I. 42660, C.I. Acid Blue 83 Brilliant indocyanine 6B, Brillantindocyanin 6B Brilliant Cyanine 6B, Serva Blue R
Identifiers
CAS Number	6104-59-2 Y
3D model (Jmol)	Interactive image
ECHA InfoCard	100.025.509
PubChem CID	61365
SMILES CCN(CC1=CC(=CC=C1)S(=O)(=O)[O-])C2=CC=C(C=C2)C(=C3C=CC(=[N+](CC)CC4=CC(=CC=C4)S(=O)(=O)[O-])C=C3)C5=CC=C(C=C5)NC6=CC=C(C=C6)OCC.[Na+]
Properties
Chemical formula	C45H44N3NaO7S2 (Sodium salt)
Molar mass	825.97 g/mol
Solubility in water	Insoluble in cold, slightly soluble in hot (bright red blue)
Solubility in ethanol	Slightly soluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Coomassie Brilliant Blue G-250

Solid Coomassie Brilliant Blue G Brilliant Blue G in Isopropanol solution
Names
Other names C.I. 42655, C.I. Acid Blue 90 Brilliant indocyanine G, Brillantindocyanin G Xylene Brilliant Cyanine G, Serva Blue G
Identifiers
CAS Number	6104-58-1
3D model (Jmol)	Interactive image
ECHA InfoCard	100.025.509
KEGG	D10799 Y
PubChem CID	6324599
SMILES CCN(CC1=CC(=CC=C1)S(=O)(=O)[O-])C2=CC(=C(C=C2)C(=C3C=CC(=[N+](CC)CC4=CC (=CC=C4)S(=O)(=O)[O-])C=C3C)C5=CC=C(C=C5)NC6=CC=C(C=C6)OCC)C.[Na+]
Properties
Chemical formula	C47H50N3NaO7S2 (Sodium salt)
Molar mass	856.03 g/mol
Solubility in water	Slightly soluble in cold, soluble in hot (bright blue)
Solubility in ethanol	Soluble
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Coomassie Brilliant Blue is the name of two similar triphenylmethane dyes that were developed for use in the textile industry but are now commonly used for staining proteins in analytical biochemistry. Coomassie Brilliant Blue G-250 differs from Coomassie Brilliant Blue R-250 by the addition of two methyl groups. The name "Coomassie" is a registered trademark of Imperial Chemical Industries.

The name Coomassie was adopted at the end of the 19th century as a trade name by the Blackley based dye manufacturer Levinstein Ltd, in marketing a range of acid wool dyes. In 1896 during the Fourth Anglo-Ashanti War, British forces had occupied the town of Coomassie (modern-day Kumasi in Ghana). In 1918 Levinstein Ltd became part of British Dyestuffs which in 1926 became part of Imperial Chemical Industries. Although ICI still owns the Coomassie trademark, the company no longer manufactures the dyes.

The blue disulfonated triphenylmethane dyes were first produced in 1913 by Max Weiler who was based in Elberfeld, Germany. Various patents were subsequently taken out on the organic synthesis.

Papers published in biochemistry journals frequently refer to these dyes simply as "Coomassie" without specifying which dye was actually used. In fact the Colour Index lists over 40 dyes with "Coomassie" in their name. There are also other Coomassie "blue" dyes. For example, the Merck Index (10th edition) lists Coomassie Blue RL (Acid Blue 92, C.I. 13390) which has a completely different structure.

The suffix "R" in the name of Coomassie Brilliant Blue R-250 is an abbreviation for Red as the blue colour of the dye has a slight reddish tint. For the "G" variant the blue colour has a more greenish tint. The "250" originally denoted the purity of the dye.

The colour of the two dyes depends on the acidity of the solution. The "G" form of the dye has been studied in detail. At a pH of less than 0 the dye has a red colour with an absorption maximum at a wavelength of 470 nm. At a pH of around 1 the dye is green with an absorption maximum at 620 nm while above pH 2 the dye is bright blue with a maximum at 595 nm. At pH 7 the dye has an extinction coefficient of 43,000 M⁻¹cm⁻¹.