E7637 Sigma

Ethidium bromide

BioReagent, for molecular biology, powder

Synonym: 3,8-Diamino-5-ethyl-6-phenylphenanthridinium bromide, EtBr, Homidium bromide


Related Categories Agarose Blends for Electrophoresis, Biochemicals and Reagents, Core Bioreagents, Ethidium Bromide, Fluorescent Probes, Labels, Particles and Stains,
grade   for molecular biology
product line   BioReagent
form   powder
mp   260-262 °C (dec.)(lit.)
suitability   suitable for gel electrophoresis


Biochem/physiol Actions

Ethidium bromide intercalates double-stranded DNA and RNA and acts as a frameshift mutagen. It can also be used in conjunction with acridine orange to differentiate between viable, apoptotic and necrotic cells.


1, 5, 25 g in glass bottle


For staining a gel after electrophoresis, dilute a sample of the stock solution to 0.5 μg/ml with water and incubate the gel for 15-30 min. Destaining is usually not needed but can be carried out in water for 15 min if decreased background is necessary. The DNA bands can then be detected on a UV light box (254 nm wavelength). Ethidium bromide can also be incorporated into the gel and running buffer at 0.5 μg/ml and visualized immediately after electrophoresis.


Ethidium bromide (EtBr) is the most commonly used nucleic acid stain for PAGE or agarose gel electrophoresis. The fluorescence of EtBr increases 21-fold upon binding to double-stranded RNA and 25-fold on binding double-stranded DNA so that destaining the background is not necessary with a low stain concentration (10 μg/ml). Ethidium bromide has been used in a number of fluorimetric assays for nucleic acids.1,2,3 It has been shown to bind to single-stranded DNA (although not as strongly) and triple-stranded DNA.4 Because of its ability to bind to DNA, EtBr is an inhibitor of DNA polymerase.5

Frameshift mutagen which intercalates double-stranded DNA and RNA.

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