Digoxigenin
Chemical compound
From Wikipedia, the free encyclopedia
Digoxigenin (DIG) is a steroid found exclusively in the flowers and leaves of the plants Digitalis purpurea, Digitalis orientalis[disambiguation needed] and Digitalis lanata (foxgloves), where it is attached to sugars, to form the glycosides (e.g. digoxin, lanatoside C).[2]
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| Names | |
|---|---|
| IUPAC name
3β,12β,14-Trihydroxy-5β-card-20(22)-enolide | |
| Systematic IUPAC name
4-[(1R,3aS,3bR,5aR,7S,9aS,9bS,11R,11aS)-3a,7,11-Trihydroxy-9a,11a-dimethylhexadecahydro-1H-cyclopenta[a]phenanthren-1-yl]furan-2(5H)-one | |
| Identifiers | |
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| ECHA InfoCard | 100.015.279 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| C23H34O5 | |
| Molar mass | 390.51 g/mol |
| log P | 2.57510[1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Uses in biotechnology
Digoxigenin is a hapten, a small molecule with high antigenicity, that is used in many molecular biology applications similarly to other popular haptens such as 2,4-Dinitrophenol, biotin, and fluorescein. Typically, digoxigenin is introduced chemically (conjugation) into biomolecules (proteins, nucleic acids) to be detected in further assays. Kd of the digoxigenin-antibody interaction has been estimated at ~12 nM [3] (compare to Kd~0.1pM for the biotin-streptavidin interaction[4]).
- DIG-binding proteins
Tinberg et al. designed artificial proteins that bind DIG. Their best binder, DIG10.3, was a 141 amino acid protein that bound DIG with a dissociation constant (Kd) of 541 (+/- 193) pM.[5]
Anti-digoxigenin antibodies with high affinities and specificity are used in a variety of biological immuno-assays (e.g. ELISA). The antibodies are labeled with dyes, enzymes or fluorescence, directly or secondarily, for visualization and detection.
Digoxigenin is thus an all-purpose immuno-tag, and in particular a standard immunohistochemical marker for in situ hybridization.[6][7] In this case it is conjugated to a single species of RNA nucleoside triphosphate (typically uridine), which is then incorporated into RNA (a "riboprobe") as it is synthesized by the cellular machinery.
It allows to make :
- sensitive non-radioactive in situ hybridization probes to detect nucleic acids in plants, able to detect 1 μg of plasmid DNA.[8]
- peptide-DIG conjugates, i.e. bradykinin assay by very sensitive chemiluminescence immunoassays.[9]
- fluorescent and DIG-labeled tracers for competitive immunoassays, i.e. to limit detect digoxin, a drug used to cure cardiac arrhythmia, down to 0.2 ng mL−1.[10]
- Digoxigenin may be conjugated to sugars to study glycosylation events,[11] even in biological systems.