Ortho-Nitrophenyl-β-galactoside
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| Ortho-Nitrophenyl-β-galactoside | |
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| Identifiers | |
| CAS number | [] |
| PubChem | |
| MeSH | |
| Properties | |
| Molecular formula | C12H15NO8 |
| Molar mass | 301.249 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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- The correct title of this article is ortho-Nitrophenyl-β-galactoside. The initial letter is shown capitalized due to technical restrictions.
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 hydrolysed.
| Major Families of Biochemicals | ||
| Peptides | Amino acids | Nucleic acids | Carbohydrates | Lipids | Terpenes | Carotenoids | Tetrapyrroles | Enzyme cofactors | Steroids | Flavonoids | Alkaloids | Polyketides | Glycosides | ||
| Analogues of nucleic acids: | Types of Glycosides | Analogues of nucleic acids: |
| Bond: | O-glycosidic bond | S-glycosidic bond | N-glycosidic bond | |
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| Geometry: | α-Glycoside | β-Glycoside | 1,4-Glycoside | 1,6-Glycoside | |
| Glycone: | Glucoside | Fructoside | Glucuronide | |
| Aglycone: | Alcoholic glycoside | Anthraquinone glycoside | Coumarin glycoside | Cyanogenic glycoside | Flavonoid glycoside | Phenolic glycoside | Saponin | Cardiac glycoside | Steviol glycoside | Thioglycoside | Glycosylamine | Bufanolide | Cardenolide | |
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