Ortho-Nitrophenyl-β-galactoside

Ortho-Nitrophenyl-β-galactoside

Chembox new
ImageFile = ONPG structure.png ImageSize =
IUPACName = ("2R,3R,4S,5R")-2-(Hydroxymethyl)-6-(2-nitrophenoxy)oxane-3,4,5-triol
OtherNames = 2-Nitrophenylgalactoside
Abbreviations = ONPG
Section1 = Chembox Identifiers
CASNo = 19710-96-4
PubChem = 123646
SMILES = O= [N+] ( [O-] )C1=CC=CC=C1O [C@@H] 2O [C@H] (CO) [C@H] (O) [C@H] (O) [C@H] 2O
MeSHName = 2-nitrophenylgalactoside
Section2 = Chembox Properties
Formula = C12H15NO8
MolarMass = 301.249
Appearance =
Density =
MeltingPt =
BoilingPt =
Section3 = Chembox Hazards
Solubility =
MainHazards =
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"ortho"-Nitrophenyl-β-galactoside (ONPG) is a colorimetric and spectrophotometric substrate for detection of beta-galactosidase activity. This compound is normally colorless. However if β-galactosidase is present, it hydrolyzes the ONPG molecule into galactose and ortho-nitrophenol. The latter compound has a yellow coloration that can be used to check for enzyme activity by means of a colorimetric assay.

Beta-galactosidase is required for lactose utilization, so the intensity of the color produced can be used as a measure of the rate that Beta-galactosidase can hydrolyze lactose.

Though ONPG mimics lactose and is hydrolysed by Beta-galactosidase, it is unable to act as an inducer for the lac operon. Without another lactose analog that can act as an inducer, such as IPTG, Beta-galactosidase will not be transcribed and ONPG will not be hydrolyzed.


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  • Ortho-nitrophenyl-β-galactoside — Figure 1 : Formule de l ONPG. Général No CAS …   Wikipédia en Français

  • ortho-Nitrophenyl-β-galactoside — IUPAC name (2R,3R,4S,5R) 2 (Hydroxymethyl) 6 (2 nitrophenoxy)oxane 3,4,5 triol …   Wikipedia

  • Ortho-nitrophényl-β-galactoside — Figure 1 : Formule de l ONPG. Général Nom IUPAC (2R,3R,4S,5R,6S) 2 (hydroxyméthyl) 6 (2 nit …   Wikipédia en Français

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  • 19710-96-4 — Ortho nitrophenyl β galactoside Ortho nitrophenyl β galactoside Figure 1 : Formule de l ONPG. Général No CAS …   Wikipédia en Français

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