Synonym: 3,8-Diamino-5-ethyl-6-phenylphenanthridinium bromide, EtBr, Homidium bromide
CAS Number: 1239-45-8
Linear Formula: C21H20BrN3
Molecular Weight: 394.31
Beilstein Registry Number: 3642536
EC Number: 214-984-6
MDL number: MFCD00011724
PubChem Substance ID: 24894683
Description
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Application 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
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.
Reconstitution 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 immediay after electrophoresis. 

Properties
assay ~95% （HPLC）
mp 260-262 °C （dec.）（lit.）

Safety
Personal Protective Equipment Eyeshields, Faceshields, full-face particle respirator type N100 （US）, Gloves, respirator cartridge type N100 （US）, type P1 （EN143） respirator filter, type P3 （EN 143） respirator cartridges
Hazard Codes T+
Risk Statements 22-26-36/37/38-68
Safety Statements 26-28-36/37-45
RIDADR UN2811 6.1/PG 1
WGK Germany 3
RTECS SF7950000